Agilent Technologies 6626A, 6625A, 6628A, 6629A User Manual

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OPERATING MANUAL

MULTIPLE OUTPUT LINEAR SYSTEM

DC POWER SUPPLY

AGILENT MODELS 6625A, 6626A,

6628A, and 6629A

Agilent Part No 06626-90001

Microfiche Part No. 06626-90002 Printed in Malaysia September, 2004

CERTIFICATION

Agilent Technologies certifies that this product met its published specifications at time of shipment from the factory. Agilent Technologies further certifies that its calibration measurements are traceable to the United States National Bureau of Standards, to the extent allowed by the Bureau's calibration facility, and to the calibration facilities of other International Standards Organization members.

WARRANTY

This Agilent Technologies hardware product is warranted against defects in material and workmanship for a period of one year from date of delivery. Agilent software and firmware products, which are designated by Agilent for use with a hardware product and when properly installed on that hardware product, are warranted not to fail to execute their programming instructions due to defects in material and workmanship for a period of 90 days from date of delivery. During the warranty period Agilent Technologies will, at its option, either repair or replace products which prove to be defective. Agilent does not warrant that the operation of the software, firmware, or hardware shall be uninterrupted or error free.

For warranty service, with the exception of warranty options, this product must be returned to a service facility designated by Agilent. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products returned to Agilen t for warranty service. Except for products returned to Customer from another country, Agilent shall pay for return of products to Customer.

Warranty services outside the country of initial purchase are included in Agilent's product price, only if Customer pays Agilent international prices (defined as destination local currency price, or U.S. or Geneva Export price).

If Agilent is unable, within a reasonable time to repair or replace any product to condition as warranted, the Customer shall be entitled to a refund of the purchase price upon return of the product to Agilent.

LIMITATION OF WARRANTY

The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the Customer, Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental specifications for the product, or improper site preparation and maintenance. NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. Agilent SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

EXCLUSIVE REMEDIES

THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER'S SOLE AND EXCLUSIVE REMEDIES. Agilent SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.

ASSISTANCE

The above statements apply only to the standard product warranty. Warranty options, extended support contracts, product maintenance agreements and customer assistance agreements are also available. Contact your nearest Agilent Technologies Sales and Service office for further information on Agilent's full line of Support Programs.

Update 1___February, 2000

Update 2___September, 2004

SAFETY SUMMARY

The following general safety precautions must be observed during all phases of operation, service, and repair of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. Agilent Technologies assumes no liability for the customer’s failure to comply with these requirements.

BEFORE APPLYING POWER.

Verify that the product is set to match the available line voltage and the correct fuse is installed.

GROUND THE INSTRUMENT.

This product is a Safety Class 1 inst rument (provided with a protective earth terminal). To minimize shock hazard, th e instrument chassis and cabinet must be connected to an electrical ground. The instrument must be connected to the ac power supply mains through a threeconductor power cable, with the third wire firmly connected to an electrical ground (safety ground) at the power outlet. For instruments designed to be hard-wired to th e ac power lines (supply mains), conn ect the protective earth terminal to a protect ive conductor before any other connection is made. Any interruption of the protective (grounding) conductor or disconnection of the protective earth terminal will cause a potential shock h azard that could result in personal inju ry. If the instrument is to be energized via an external autotransformer for voltage reduction, be certain that the autotransfo r mer common terminal is connect ed to the neutral (earthed pole) of the ac power lines (supply mains).

FUSES.

Only fuses with the required rated current, voltage, and specified type (normal blow, time delay, etc.) should be used. Do not use repaired fuses or short circuited fuseholders. To do so could cause a shock or fire hazard.

DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.

Do not operate the instrument in the presence of flammable gases or fumes.

KEEP AWAY FROM LIVE CIRCUITS.

Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made by qualified service personnel. Do not replace components with power cable connected. Under certain conditions, dangerous voltages may exist even with the power cable removed. To avoid injuries, always disconnect power, discharge circuits and remove external voltage sources before touching components.

DO NOT SERVICE OR ADJUST ALONE.

Do not attempt internal service or adjustment unless another person, capable of rendering first aid and resuscitation, is present.

DO NOT EXCEED INPUT RATINGS.

This instrument may be equipped with a line filter to reduce electromagnetic interference and must be connected to a properly grounded receptacle to minimize electric shock hazard. Operation at line voltages or frequencies in excess of those stated on the data plate may cause leakage currents in excess of 5.0 mA peak.

SAFETY SYMBOLS.

Instruction manual symbol: the product will be marked with this symbol when it is necessary for the user to refer to the instruction manual (refer to Table of Contents) .

Indicates hazardous vo ltages.

Indicate earth (ground) terminal.

The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which, if not correctly performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the indicated conditions are fully understood and met.

The CAUTION sign denotes a hazard. It calls attention to an operating procedure, or th e like, which, if not correctly performed or adhered to, coul d result in damage to or destruction of part or all of the product. Do not proceed beyond a CAUTION sign until the indicated conditions are fully understood and met.

DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.

Because of the danger of introducing additional hazards, do not install substitute parts or perform any unau t horized modification to the instrument. Return the instrument to an Agilent Technologies Sales and Service Office for service and repair to ensure that safety features are maintained.

Instruments which appear damaged or defective should be made inoperative and secured against unintended operation until they can be repaired by qualified service personnel

SAFETY SUMMARY (continued)

GENERAL

Any LEDs used in this product are Class 1 LEDs as per IEC 825-1.

This ISM device complies with Canadian ICES-001. Cet appareil ISM est conforme à la norme NMB-001 du Canada.

ENVIRONMENTAL CONDITIONS

This instrument is intended for indoor use in an installation category II, pollution degree 2 environment. It is designed to operate at a maximum relative humidity of 95% and at altitudes of up to 2000 meters. Refer to the specifications tables for the ac mains voltage requirements and ambient operatin g temperature range.

SAFETY SYMBOL DEFINITIONS

Symbol Description Symbol Description

Direct current Terminal for Line conductor on permanently

installed equipment

Alternating current Caution, risk of electric shock

Both direct and alternating current Caution, hot surface

Three-phase alternating current Caution (refer to accompanying documents)

Earth (ground) terminal In position of a bi-stable push control

Protective earth (ground) terminal Out position of a bi-stable push control

Frame or chassis terminal On (supply)

Terminal for Neutral conductor on permanently installed equipment

Terminal is at earth potential (Used for measurement and control circuits designed to be operated with one terminal at earth potential.)

Herstellerbescheinigung

Diese Information steht im Zusammenhang mit den Anforderungen der Maschinenläminformationsverordnung vom 18 Januar 1991.

* Schalldruckpegel Lp <70 dB(A) * Am Arbeitsplatz * Normaler Betrieb * Nach EN 27779 (Typprüfung).

Manufacturer’s Declaration

This statement is provided to comply with the requirements of the German Sound Emission Directive, from 18 January 1991.

* Sound Pressure Lp <70 dB(A) * At Operator Position * Normal Operation * According to EN 27779 (Type Test).

Off (supply)

Standby (supply) Units with this symbol are not completely disconnected from ac mains when t his switch is off. To completely disconnect the unit from ac mains, either disconnect the power cord or have a qualified electrician install an external switch.

DECLARATION OF CONFORMITY

According to ISO/IEC Guide 22 and CEN/CENELEC EN 45014

Manufacturer’s Name and Address

Responsible Party Agilent Technologies, Inc. Agilent Technologies (Malaysia) Sdn. Bhd 550 Clark Drive, Suite 101 Budd Lake, New Jersey 07828 USA

Declares under sole responsibility that the product as originally delivered

Product Names a) Multiple Output 40 W and 80 W system dc Power Supplies

Model Numbers a) 6621A, 6622A, 6623A; 6624A, 6627A

Product Options This declaration covers all options and customized products based on the above

Complies with the essential requirements of the Low Voltage Directive 73/23/EEC and the EMC Directive 89/336/EEC (including 93/68/EEC) and carries the CE Marking accordingly.

EMC Information ISM Group 1 Class A Emissions

As detailed in Electromagnetic Compatibility (EMC), Certificate of Conformance Number

Assessed by: Celestica Ltd, Appointed Competent Body

Safety Information and Conforms to the following safety standards.

This DoC applies to the above-listed products placed on the EU market after:

Alternate Manufacturing Site

Malaysia Manufacturing Bayan Lepas Free Industrial Zone, PH III 11900 Penang,

Malaysia

b) Multiple Output 25 W and 50 W precision system dc Power Supplies

b) 6625A; 6626A; 6628A; 6629A (and other customized products based upon the above)

products.

CC/TCF/00/076 based on Technical Construction File (TCF) HPNJ3, dated Oct. 29, 1997

Westfields House, West Avenue Kidsgrove, Stoke-on-Trent Straffordshire, ST7 1TL United Kingdom

IEC 61010-1:2001 / EN 61010-1:2001 UL 1244 CSA C22.2 No. 1010.1:1992

January 1, 2004 Date Bill Darcy/ Regulations Manager

For further information, please contact your local Agilent Technologies sales office, agent or distributor.

Authorized EU-representative: Agilent Technologies Deutschland GmbH, Herrenberger Straβe 130, D 71034 Böblingen, Germany

Revision: B.00.00 Issue Date: Created on 11/24/2003 3:33

Document No. 662xA.11.24.doc

WHAT THIS MANUAL CONTAINS

It contains information relating to the installation, operation, and programming of these supplies as outlined below. Maintenance and troubleshooting instructions are given in a separate Service Manual (Agilent Part No. 06626-90003).

Chapter 1.--General Information

Chapter 1 contains a general description of the power supplies as well as instrument specifications and information concerning options and accessories.

Chapter 2.--Installation Procedures

Chapter 2 contains information to prepare the supply for use. Included in this chapter are power requirements, line voltage conversion, and GP-IB interface connections.

Chapter 3.--Getting Started

Chapter 3 contains a brief description of the supply’s front panel controls and indicators and describes how to turn on the supply and to check it’s operation. An introd uction to remote operation over the GP-IB is also given to help a first time user get started quickly.

Chapter 4.--Output Connections and Opera ting Information

Chapter 4 contains information about making connections to the supply’s output terminals. General operating information is also provided.

Chapter 5.--Remote Operation

Chapter 5 contains all of the information required to op erate the supply remotely via a GP-IB computer. All of the commands that can be used to program the supplies are described.

Chapter 6.--Local Operation

Chapter 6 contains instructions on using all of the front panel controls and indicators.

Appendix A--Calibration Procedure

Appendix A contains programming steps and procedures that are required to calibrate your power supply. It is recommended that the power supply be calibrated yearly.

Appendix B--Programming with Series 200/300 Computer

Appendix B contains Series 200/300 Computer programming examples (in Agilent extended BASIC language) for your Power Supply’s most fr e quently used functions.

Appendix C--Command Summary

Appendix C contains an alphabetical listing of all commands that can be sent to a supply.

Appendix D--Error Messages

Appendix D contains a listing and brief explanation of all error codes and messages for all programming and hardware errors.

Appendix E - Manua l Backdating

Appendix E contains backdating in formation for units with Serial numbers lower than those listed on the title page.

1 General Information

Introduction...................................................................................................................................................11

Safety Considerations....................................................................................................................................11

Instrument and Manual Identification...........................................................................................................11

Options..........................................................................................................................................................11

Accessories....................................................................................................................................................12

Description ...................................................................................................................................................12

Basic Operation.............................................................................................................................................14

GP-IB Board..............................................................................................................................................14

Output Boards............................................................................................................................................15

Specifications................................................................................................................................................15

Qualifying Conditions...............................................................................................................................15

Definitions.................................................................................................................................................15

2 Installation

Introduction...................................................................................................................................................25

Initial Inspection............................................................................................................................................25

Location and Cooling....................................................................................................................................25

Input Power Requirements............................................................................................................................26

Line Fuse.......................................................................................................................................................27

Power Cord....................................................................................................................................................28

Line Voltage Conversion...............................................................................................................................29

GP-IB Interface Connection.............. ............................................................................................................29

3 Getting Started

Introduction ..................................................................................................................................................31

Front Panel Controls and Indicators..............................................................................................................31

Turning On Your Supply...............................................................................................................................36

Normal Self Test Indications.....................................................................................................................36

Self Test Errors..........................................................................................................................................37

Checking Out Your Supply Using Local Control..........................................................................................37

Voltage Test..............................................................................................................................................38

Overvoltage Test.......................................................................................................................................38

Current Test...............................................................................................................................................38

Changing Resolution Range......................................................................................................................39

Introduction To Remote Operation....... ........................................................................................................39

Enter/Output Statements............................................................................................................................40

Reading the GP-IB Address......................................................................................................................40

Changing the GP-IB Address....................................................................................................................40

Sending a Remote Command....................................................................................................................41

Getting Data from the Supply....................................................................................................................41

Often Used Commands..............................................................................................................................41

Returning the Supply to Local Mode........................................................................................................43

4 Output Connections and Operating Information

Introduction ..................................................................................................................................................45

Output Ranges...............................................................................................................................................45

Operating Quadrants..................................................................................................................................46

Operating Range........................................................................................................................................47

Protection Features........................................................................................................................................48

Connecting The Load....................................................................................................................................49

Wire Size Selection...................................................................................................................................49

Multiple Loads.............................. ............................................................................................................50

Positive and Negative Voltages.................................................................................................................51

Remote Voltage Sensing............................................................................................................................... 51

Remote Sense Connections.......................................................................................................................52

Output Noise Considerations.....................................................................................................................53

Programming Response Time with an Output Capacitor..........................................................................53

Open Sense Leads......................................................................................................................................54

Overvoltage Trigger Connections.................................................................................................................54

External Trigger Circuit............................................................................................................................54

Power Supply Protection Considerations .......................... ...........................................................................55

Battery Charging........................... ............................................................................................................55

Capacitive Load Limitation.......................................................................................................................56

Parallel Operation..........................................................................................................................................56

CV Operation............................................................................................................................................57

CC Operation.............................................................................................................................................58

Remote Sensing.........................................................................................................................................58

Specifications for Parallel Operation.........................................................................................................58

Series Operation............................................................................................................................................59

CV Operation............................................................................................................................................59

CC Operation.............................................................................................................................................60

Remote Sensing.........................................................................................................................................60

Specifications for Series Operation...........................................................................................................60

Bi-Polar Operation....................................................................................................................................61

5 Remote Operation

Introduction ..................................................................................................................................................63

GP-IB Operation............................................................................................................................................63

Interface Functions....................................................................................................................................63

GP-IB Address Selection...........................................................................................................................64

Power-On Service Request (PON)............................................................................................................65

Programming Syntax.....................................................................................................................................65

Numeric Data............................................................................................................................................67

Order of Execution....................................................................................................................................70

Terminators................................ ...............................................................................................................70

Initial Conditions...........................................................................................................................................71

Power Supply Commands.......................................................................................................... ...................71

Voltage Programming...............................................................................................................................71

Current Programming................................................................................................................................73

Range Programming..................................................................................................................................73

Output On/Off.................................... .......................................................................................................74

Overvoltage Protection..............................................................................................................................74

Overcurrent Protection........................... ...................................................................................................75

Multiple Output Storage and Recall..........................................................................................................75

The Clear Command..................................................................................................................................76

Status Reporting........................................................................................................................................76

Service Request Generation....................... ...............................................................................................79

Reprogramming Delay............................. .................................................................................................80

Display On/Off.......................................................................................................................................... 81

Other Queries.............................................................................................................................................82

Table Of Contents (continued)

6 Local Operation

Introduction ..................................... .............................................................................................................85

Local Mode....................................................................................................................................................85

Table Of Contents (continued)

Local Control Of Output Functions............................................................................................................... 85

General........................................... ...........................................................................................................85

Setting Voltage and Voltage Range...........................................................................................................86

Setting Current and Current Range............................................................................................................87

Enabling/Disabling an Output...................................................................................................................87

Setting Overvoltage Protection..................................................................................................................88

Resetting Overvoltage Protection..............................................................................................................88

Enabling/Disabling Overcurrent Protection..............................................................................................88

Resetting Overcurrent Protection..............................................................................................................88

Local Control Of System Functions..............................................................................................................88

Setting the Supply’s GP-IB Address..........................................................................................................88

Displaying Error Messages........................................................................................................................89

Storing and Recalling Voltage and Current. Settings for all Outputs........................................................89

A Alignment Procedures

Introduction...................................... .............................................................................................................91

Test Equipment and Setup Required.............................................................................................................91

Calibration Program......................................................................................................................................91

Alignment Program.......................................................................................................................................95

B Programming With a Series 200/300 Computer

Introduction ................................................................................................................................................103

I/O Path Names...................... .....................................................................................................................103

Voltage and Current Programming.............................................................................................................103

Voltage and Current Programming With Variables... .................................................................................104

Voltage and Current Readback....................................................................................................................104

Programming Power Supply Registers........................................................................................................105

Present Status...................... ....................................................................................................................105

Service Request and Serial Poll...............................................................................................................106

Error Detection .................... ...................................................................................................................107

Stored Operating States...........................................................................................................................108

C Command Summary

Introduction.................................................................................................................................................109

D Error Messages

Introduction.................................................................................................................................................117

Power-On Self Test Messages.....................................................................................................................117

Error Responses...........................................................................................................................................117

Test Responses............................................................................................................................................117

E Manual Backdating

Introduction ................................................................................................................................................121

Make Changes.................…………………………………………………………………………………...121

Agilent Sales and Support Office

Contacts ......................................................................................................................................................122

General Information

Introduction

This chapter contains a general description of your power supply as well as its performance specifications. Information about options, accessories, and GP-IB cables is also provided. This manual describes the Agilent 6625A, 6626A, 6628A, and Agilent 6629A power supplies. Unless stated otherwise, the information in this manual applies to all of these models. Information that is specific to one model only is identified as such in this manual.

Safety Considerations

This product is a Safety Class 1 instrument, which means that it is provided with a protective earth terminal. This terminal must be connected to a power source that has a 3-wire ground receptacle. Review the instrument and this manual for safety markings and instructions b e fore operation. Refer to the Safety Summary page at the beginning of this manua l for a summary of general safety information. Safety information for specific procedures is located at appropriate places in this manual.

Instrument and Manual Identification

Agilent Technologies power supplies are identified by a two-part serial number, i.e. 2601A-00101. The first part of the serial number (the prefix) is a number/letter combination that denotes either the date of manufacture or the date of a significant design change. It also indicates the country of origin. (Starting at 1960, 26 = 1986; 01 = the first week of the year; A = U.S.A.) The second part of the serial number is a different sequential number assigned to each instrument starting with 00101.

Options

Options 100,120, 220, and 240 simply determine which line voltage is selected at the factory. For information about changing the li ne voltage setting, see line voltage conversion para graph on page 29.

Option 750 consists of a fault indicator (FLT) and remote inhibit (INH) circuit and relay control, which provide additional shutdown protection should either the GP-IB and/or controller fail. This Option is described in a separate document entitled, ’’Appendix E Option 750 Operating Instructions for the Multiple Output Linear System DC Power Supply, Agilent Models 6621A, 6622A, 6623A, 6624A, and 6627A’’ (Agilent P/N 5957-6372).

#100 Input power, 100 Vac, 47-66 Hz #120 Input power, 120 Vac, 47-66 Hz #220 Input power, 220 Vac, 47-66 Hz #240 Input power, 240 Vac, 47-66 Hz #750 Fault (FLT) Remote Inhibit (INH) and Relay Control #908 One rack mount kit (5062-3977) #909 One rack mount kit with handles (5062-3983)

#0L2 One extra operating manual #0B3 One service manual

General Information

Accessories

10833A GP-IB cable, 1 m (3.3 ft) 10833B GP-IB cable, 2 m (6.6 ft) 10833C GP-IB cable, 4 m (13.2 ft) 10833D GP-IB cable, 0.5 m (1.6 ft) 10834A GP-IB connector extender Slide mount kit (1494-0059)

Description

The Agilent power supply features a combination of programming capabilities and linear power supply performance that make them ideal for systems applications. The models in this family offer a total of up to 200 watts of output power, with voltages up to 50 volts and currents up to 2 amps. The output combinations that correspond to each model are shown in Table 1-1. Each isolated output has a high resolution and standard resolution range, as shown in Figure 1-1.

Table 1-1 Output Combinations Available

Model Output 1 Output 2 Output 3 Output 4

Agilent 6625A 25 W 50 W -- -Agilent 6626A 25 W 25 W 50 W 50 W Agilent 6628A 50 W 50 W -- -Agilent 6629A 50 W 50 W 50 W 50W

Figure 1-1. Output Operating Range

Output 2 of the Agilent 6625A and outputs 3 and 4 of the Agilent 6626A and all outputs of the Agilent 6628A and Agilent 6629A have an "L’’ shaped characteristic. The L shaped characteristic allows you to use the same output to power loads with different voltage and current requirements. The power supply automatically selects one of the operating ranges based on the last parameter (voltage or current) that is set. If a high resolution o r a standard resolution application is required for either voltage or current, VRSET and IRSET should be used (see Appendix C-Command Summary). Additionally, each output contains an active downprogrammer, which means that voltage downprogramming can be accomplished as quickly as upprogramming, even without a load.

General Information

The power supplies allow up to a 10 volt sense lead drop. This feature makes them ideal for test system applications where remote sensing is used.

The output voltage and current for any output can be monitored with the front panel display. Output specific error messages are also displayed. Front panel annunciators show the ope rating status of the instrument. The front pa nel keypad lets you set and readback the voltage limit, current limit, and overvoltage trip level of any output. With the ke ypad, you can also enable or disable outputs, enable overcurrent protection, reset overvoltage and overcurrent protection, and return to local operating mode.

Your multiple output power supply can be b oth a listener and a talker on the GP-IB. (GP-IB is Agilent Technologies’ implementation of IEEE-488). The built-in interface is tailored to the supply, resulting in simpler programming. Voltage and current settings can be sent directly to the specified output in volts and amps.

Service can be requested from your power supply for up to 10 reasons. The supply responds to a serial poll by identifying the output on which the fault occurred. Self-contained measurement and readback capability eliminate the need for externally scanning the outp uts using a separate DVM. Upon command, the supply will measure its output voltage or current and return the value on the GP-IB. The following functions are implemented via the GP-IB:

Voltage and current programming. Programmable resolution range. Voltage and current measurement and readback. Present and accumulated status readback. Programmable service request mask. Programmable overvoltage and overcurrent protection. Voltage and current range programming. Storage and recall of programmed voltage and current values for all outputs. Queries of programmed functions or settings. Output enable or disable. Programming syntax erro r detection. Programmable delay time for service request and OCP mask. Voltage, current, and overvoltage calibration. GP-IB interface selftest. Message display capability on the fro nt pa nel.

Output connections are made to rear panel screw ter minals. Either the positive or negative output terminal can b e grounded, or the output can be floated up to ± 240 Vdc (includi ng output voltage) from chassis gro und. Output voltage can be locally or remotely sensed, and identical outputs can be operated in series or parallel combinations for increased output voltage or current capability. As shipped from the factory, the power supply is jumpered for local sensing.

Your power supply can be calibrated without having to remove the cover or even having to remove it from your system cabinet. This feature allows you to calibrate the supply at its normal operating temperature. The recommended calibration interval is one year. Refer to Appendix A of thi s manual for complete calibration details. A calibration security jumper is available inside the unit. Access is described in the service manual.

General Information

Basic Operation

Figure 1-2 is a block diagram that illustrates the major assemblies contained within the power supply. As shown in the figure, each supply includes a power transformer, two or more output boards, a GP-IB board, and front panel (display and control keys).

Figure 1-2. Block Diagram

The appropriate ac input voltage is applied to each output board where it is converted to a raw dc voltage which is subsequently linearly regulated to become the dc output voltage. The magnitude of the output and the mode of operation are determined by the load and the data received from the GP-IB computer or from the front panel.

Each power supply model contains one output board for each output that it provides.

GP-IB Board

The GP-IB board provides the interface between the user and the multiple outputs of the power supply. Each output board is actually an output channel that can be individually selected and controlled over the GP-IB or from the supply’s front panel. Circuits on the GP-IB board interpret commands from the GP-IB or from the front panel to control the selected output.

The GP-IB board also processes measurement and status data received from the output boards. This data may be read back over the GP-IB and/or displayed on the supply’s front panel.

The power supply has no potentiometers. Each output is individually calibrated over the GP-IB using calibration commands (see Appendix A). Correction factors are calculated by the power supply during calibration and are stored in a non-volatile memory which is located on the supply’s GP-IB board. The supply contains no batteries.

General Information

Output Boards

The output boards are linear dc power supplies. Each isolated output operating boundary curve is shown in Figure 1-1.

The ac input to each output board is rectified and applied to a regulator circuit. Each output board employs series regulation techniques. A regulator element is connected in series with the load and operates in the linear region (between saturation and cutoff) of the transistor characteristic curve. Regulation is achieved by varying the conduction of the series element in response to a change in line voltage or circuit load.

The output board receives digital signals from the GP-IB board and converts them to analog signals which program the output voltage, current, and o vervoltage values. The output may be programmed remotel y over the GP-IB using commands (see Chapter 5) or locally from the supply’s front panel using the control keys (see Chapter 6).

The output board can be commanded to send measurement and status data back over the GP-IB and/or front panel. The data is sent back via the supply’s GP-IB board. GP-IB readback capabilities include o utput voltage and current, present a nd accumulated status, and all programmed settings. The front panel LCD display can indicate the output voltage and current, the supply’s GP-IB address, error messages, and programmed values. Annunciators on the front panel indicate the operating status of the selected output (output board).

Specifications

Table l-2 lists the performance specifications for the Agilent 662xA power supplies. Performance specifications describe the instrument’s warranted performance. The service manual, Option 9l0, contains procedures for verifying the

performance specifications.

Table 1-3 lists the supplemental characteristics for the Agilent 662xA supplies. Supplemental characteristics are type-tested or typical values, which are based on a product sample and, while representative, are not guaranteed.

Qualifying Conditions

All performance specifications apply over the full operating temperature range of the power supply (0 to 55°C) unless otherwise specified. All regulation, accuracy, etc. specifications are plus or minus the values listed. All measurements are made at the rear terminals of the supply with a resistive load and local sensing unless otherwise specified. Voltage measurements are made from the + S to the - S terminals. Overvoltage measurements are made from the + V to the - V terminals. + Current refers to the output acting as a current source while - Current refers to the output acting as a current sink.

Definitions Load effect

output in question. Source effect: Maximum steady state change in the regulated output parameter due to a change in the source voltage

within rated values. Cross regulation: Maximum steady state change in the regulated output parameter due to a change in load resistance on

any other output(s). Programming accuracy: (Calibration temp ± 5°C) Maximum difference between the programmed value and the actual

output.

: Maximum steady state change in the regulated output parameter due to a change in load resistance on the

Readback accuracy: (Calibration temp ±5°C) Maximum error in reading back an output parameter. Expressed as a percentage of the reading, plus a constant.

General Information

Output response time: Beginning at the time the power supply has finished processing a VSET command (change output voltage), the maximum time for the output voltage to settle to within a settling band about the final value from any specified operating point. This value must be added to the command processing time to obtain total programming time (see Figure 1-3). Time constant is the maximum time required for the voltage to reach 63% of its final value.

Figure 1-3. Output Response Characteristics

Temperature coefficient: Maximum change in the regulated output parameter per °C change in ambient temperature

after a 30 minute warmup. Expressed as a percentage plus a constant per degrees C. (Plus a constant for readback temperature coefficient).

Long Term Drift: Maximum change of regulated output voltage or current during an 8-hour period following a 30 minute warmup, with all influence and control quantities maintained constant. Expr essed as a percentage of the setting plus a constant.

Short Term Drift: Maximum change of regulated output voltage or current within 30 minutes after a line and/or load change. Expressed as a percentage of the setting plus a constant.

Output Noise (PARD): PARD replaces the former term ripple and noise. PARD is the periodic and random deviation of dc output voltage or current from its average value, over a specified bandwidth and with all influence and control quantities maintained constant.

Programming resolution: Average programming step size. Current Sinking (- Current): Each output can sink as well as source current. The sinking capabilit y is not programmable

and depends upon the output voltage. The current sinking cap ability is described in greater detail in Chapter 4.

Table 1-2. Specifications

PERFORMANCE SPECIFIC ATIONS: (0 to 55 °C unless otherwise specified) DC Output Ranges: All outputs will accept voltage programming commands 1% higher than those listed and

current programming commands 3% higher than those listed.

Output Power 25 Watt Output 50 Watt Output

Output Range Lo Range Hi Range Lo Range Hi Range Output Volts 0-7 V 0-50 V 0-16 V 0-50 V Output Amps 0-15 mA 0-500 mA 0-200 mA 0-2 A

Load Effect (Regulation):

Voltage 0.5 mV 0.5 mV 0.5 mV 0.5 mV

+ Current 0.005 mA 0.005 mA 0.01 mA 0.015 mA

General Information

Table 1-2. Specifications (continued)

Source Effect:

Voltage 0.5 mV 0.5 mV 0.5 mV 0.5 mV + Current 0.005 mA 0.005 mA 0.01 mA 0.01 mA

Programming Accuracy:

Note: The programming accuracy specifications may degrade slightly when the unit is subjected to an RF field equal to or greater than 3 volts/meter. Voltage 0.016% + 1.5 mV 0.016% + 10 mV 0.016% + 3 mV 0.016% + 10 mV + Current OVP 0.13% + 475 mV 0.13% + 475 mV 0.13% + 475 mV 0.13% + 475 mV

Measurement/Readback Accuracy*

Voltage 0.016% + 2 mV 0.016% + 10 mV 0.016% + 3.5 mV 0.016% + 10 mV

Current 0.03% + 15 µA 0.03% + 130 µA 0.04% + 250 µA 0.04% + 550 µA

Load Transient Recovery Time :(all outputs)

75 µS maximum to recover to within 75 mV of nominal value following a load change from 0.1 A to 100% of the maximum rated current

Maximum Output Noise: (PARD) (20 Hz-20 MHz)

0.04% + 15 µA 0.04% + 100 µA 0.04% + 185 µA 0.04% + 500 µA

CV pk-to-pk 3 mV 3 mV 3 mV 3 mV CV rms 0.5 mV 0.5 mV 0.5 mV 0.5 mV +CC rms 0.1 mA 0.1 mA 0.1 mA 0.1 mA

AC Input Voltage and Frequency:

Nominal Line l00, 120, 220, or 240 Vac Amplitude +6% to -13% of nominal line voltage Frequency 47 to 66 Hz

Note at low line, the supply will operate with up to 3/4 o hm line resistance

*For a ± 5 ° C range about the calibration temperature

Table 1-3. Supplemental Characteristics

Output Power 25 Watt Output 50 Watt Output

Output Range Lo Range Hi Range Lo Range Hi Range Output Volts 0-7 V 0-50 V 0-16 V 0-50 V Output Amps 0-15 mA 0-500 mA 0-200 mA 0-2 A

Temperature Coefficient-Programming:

Voltage (0.003%+0.1 mV)

per° C

+ Current

OVP (0.013% + 1 mV)

(0.0035% + 1.5 µA)

per° C

(0.003%+0.1 mV)

per° C

(0.0035% + 6 µA)

per° C

(0.013% + 2 mV)

per° C

(0.003%+0.1 mV)

per° C

(0.0035% + 30 µA)

per° C

(0.013% + 1 mV)

per° C

(0.003%+0.1 mV)

per° C

(0.0035% + 50 µA)

per° C

(0.013% + 2 mV)

per° C

General Information

Table 1-3. Supplemental Characteristics (continued)

Output Power 25 Watt Output 50 Watt Output

Output Range Lo Range Hi Range Lo Range Hi Range Output Volts 0-7 V 0-50 V 0-16 V 0-50 V Output Amps 0-15 mA 0-500 mA 0-200 mA 0-2 A

Temperature Coefficient-Measurement:

Voltage (0.002% + 0.1 mV)

per° C +0.5 mV

Current (0.0025% + 1.5 µA)

per° C + 1 µA

Long Term Drift: (In an 8 hour period following a 30 minute warm up)

Voltage 0.006% + 0.5 mV 0.006% + 2 mV 0.006% + 0.5 mV 0.006% + 2 mV + Current

Short Term Drift: (Within 30 minutes after a line and/or load change):

Voltage 0.002 + 0.5 mV 0.002 + 1 mV 0.002 + 0.5 mV 0.002 + 1 mV + Current

DC Floating Voltage:

No output terminal may be more that 240 Vdc from any other terminal or from chassis ground. Also, no overvoltage terminal may be more than 240 Vdc from any other terminal or chassis ground.

Remote Sense Capability: (see pages 50 - 52):

Outputs can maintain specifications with up to 10 volt total in the remote sense lead s.

0.01% + 5 µA 0.01% + 20 µA 0.01% + 40 µA 0.01% + 60 µA

0.01% + 2 µA 0.01% + 20 µA 0.01% + 25 µA 0.01% + 60 µA

(0.002% + 0 .1 mV) per° C +4 mV

(0.0025% + 10 µA)

per° C + 40 µA

(0.002% + 0 .1 mV) per° C +1 mV

(0.0025% + 20 µA)

per° C + 15 µA

(0.002% + 0 .1 mV) per° C +4 mV

(0.0025% + 50 µA)

per° C + 150 µA

AC Input Power Programming Resolution:

Voltage + Current OVP 230 mV 230 mV 230 mV 230 mV

Readback Resolution:

Voltage + Current

- Current

Fixed Overvoltage Protection: (Measured at output terminals +V and -V)

Minimum 56 V 56 V 56 V 56 V

Nominal 60 V 60 V 60 V 60 V

Maximum 64 V 64 V 64 V 64 V

General Information

: 550 Watts

460 µV

1 µA 33 µA 13 µA 131 µA

483 µV

1 µA 48 µA 14 µA 160 µA 1 µA 37 µA 14 µA 151 µA

3.2 mV 1 mV 3.2 mV

3.3 mV 1.1 mV 3.3 mV

Table 1-3. Supplemental Characteristics (continued)

High Line Inrush Current: 100 V Opt 120 V Opt 220 V Opt 240 V Opt

Peak Value 85 A 85 A 50 A 50 A

rms Value 6.3A 5.7 A 3.0 A 3.0 A

Fuse Rating 8 A 8 A 4 A 4 A

GP-IB Interface Capabilities:

SH1. AH1, T6, L4, SR1, RL1, PP1, DC1, DT0, C0, E1

Current Sink Capability:

25 Watt output: 0.50 A 50 Watt output: 1.0 A (2.0 A below 16 V)

Command Processing Time: (see Figure 1-3) 7 milliseconds typical (with front p a nel disabled). Using STD and RCL commands allows you to change all the voltage and current settings in abo ut 1 0 mS (with front panel disabled).

Maximum Output Programming:

Response Time 6 mS 6 mS 6 mS 6 mS Settling Band 50 mV 50 mV 50 mV 50 mV

Maximum Time

Constant

750 µS 750 µS 750 µS 750 µS

Series and Parallel operation:

Two outputs can be operated directly in parallel or can be connected for straight series operation. Refer to Chapter 4 for more information.

Reactive Load Capability:

All outputs have been designed with the ability to operate with significant reactive loads without instability (refer to Figures 1-4 through 1-6)

Safety Agency Compliance:

This series of power supplies is designed to comply with the following standards: IEC 348, UL 1244, and CSA 22.2 No. 231.

Dimensions (all models):

Height 132.6mm (5.22 in) Width 425.5mm (16.75 in.) Depth 497.8mm (19.6 in.)

General Information

Table 1-3. Supplemental Characteristics (continued)

Weight:

Agilent 6625A, 6628A Agilent 6626A, 6629A

Net 15.5 kg (34 lbs.) 17.7 kg (39 lbs.)

Shipping 20.8 kg (46 lbs.) 23 kg (51 lbs.)

Load Cross Regulation:

Voltage 0.25 mV 0.25 mV 0.25 mV 0.25 mV + Current 0.005 mA 0.005 mA 0.01 mA 0.01 mA

General Information

Figure 1-4. CV Operation with Capacitive Load, Stability Graph for all Outputs

General Information

Figure 1-5. Output Noise (Typical) CC Mode

General Information

Figure 1-6. Output Noise (Typical) CV Mode

Figure 1-7. Output Impedance (Typical) Graph (See Supplemental Characteristics)

General Information

Installation

Introduction

This chapter contains instructions for checking and mounting your power supply, connecting your supply to ac power, converting it from one line voltage to another, and connecting the GP-IB cable.

The power supply generates operating magnetic fields which may affect the operation of other instruments. If your instrument is susceptible to magnetic fields, do not locate it in the immediate vicinity of the power supply. Typically, at three inches from the power supply, the electromagnetic field is less than 5 gauss.

Initial Inspection

Your instrument was thoroughly inspected and tested before it left the factory. As soon as you receive it, remove the power supply from its packing case and check to make sure it has not been damaged in shipment. Check that there are no broken connectors or keys, and that the cabinet and panel surfaces are free from dents and scratches. Check the rear panel terminal blocks and front panel display for any cracks. If damage is found, you should file a claim with the carrier immediately and notify the Agilent Technologies Sales and Service office nearest you.

Chapter 3 of this manual includes an electrical turn-on check-out procedure which, when carried out successfully, will give you a high level of confidence that the power supply is operating in accordance with its specifications. Detailed electrical checks complete with verification procedures are included in the Service Manual.

Keep the original packing materials for the carrier’s inspection if there was damage, or in case any equipment has to be returned to Agilent Technologie s. Warranty information is printed on the inside cover of this manual. Remember to send a detailed description of the failure and symptoms when returning the power supply for service. Your Agilent Technologies Sales and Service office will furnish the address of the neares t service office to which the instrument can be shipped.

Location and Cooling

Your power supply can operate without loss of performance within the temperature range of 0 to 55 ° C (measured at the fan intake). The fan, located at the rear of the unit, cools the supply by drawing air in through the openings on the rear panel and exhausting it through openings on the sides. Using Agilent Technologies rack mount kits will not impede the flow of air.

Because the power supply is fan cooled, it must be installed in a location that allows sufficient space at the rear and the sides for adequate circulation of air. Either side may be restricted to have as little as 1 inch (25 mm) space.

Figure 2-1 gives the dimensions of the power supply cabinet. These dimensions apply to both models. The cabinet has plastic feet that are shaped to ensure self-alignment when stacked with other Agilent Technologies System II cabinets. The feet may be removed for rack mounting.

The power supply can be mounted in a standard 19 inch rack panel or enclosure. Rack mounting accessories for this unit are listed under options (page 11) o f Chapter 1. Complete installation instruction s are included with each rack mounting kit. Instrument support rails are required for non-stationary installations. These are normally supplied with the cabinet and are not included with the rack mounting kits.

Installation

Figure 2-1. Outline Diagram

Input Power Requirements

You can operate this power supply from a nominal 100 V, 120 V, 220 V or 240 V single phase power source at 47 to 66 Hz. The input voltage range, maximum input current, high line inrush current (PK), and the fuse required for each of the nominal inputs are listed in Table 2-1. You can check the line voltage setting of your supply by examining the door on the line module. This is located on the rear panel of your supply as shown in Figure 2-2. The red mark that appears in one of the four windows on the line module indicates the line voltage setting for which your supply is set.

If necessary, you can convert the supply from one line voltage setting to another by following the instructions under LINE VOLTAGE CONVERSION (see page 29).

Table 2-1. Input Power

Nominal

Voltage

100 V 6.3 A 85 A 8 AM 120 V Nominal 5.7 A 85 A 8 AM 220 V -13%, +6% 3.0 A 50 A 4 AM 240 V 3.0 A 50 A 4 AM

Line Voltage Range Maximum Input Current

(rms.)

High Line Inrush

Current (PK)

Fuse

Line Fuse

The ac line fuse is located behind the door on the line module (see Figure 2-3). To access the fuse, remove the power cord and push against the tab on the line module in the direction of the ac input socket. The current rating of the fuse is based on the line voltage setting of your supply. Table 2-2 gives the Agilent part numbers for the fuses that should be used with specific line voltages.

Installation26

Figure 2-2. Rear Panel Detail (Agilent 6626A Shown)

Table 2-2 Line Fuses

Line

Voltage

100/120 V 8AM 2110-0342 220/240 V 4AM 2110-0055

Note: All fuses are rated for 250 V.

Fuse

Needed

Agilent Part Number (for ¼ X 1¼ in. fuses

only)

Figure 2-3. Line Module Detail

Installation

Power Cord

The power supply is shipped from the factory with a power cord that has a plug appropriate for your location. Figure 2-4 shows the standard configuration of plugs used by Agilent Technologies. Below each drawing is the Agilent part number for the replacement power cord equipped with a plug of that configuration. If a different power cord is required, contact the nearest Agilent Technologies Sales and Service office.

For your protection, the National Electrical Manufacturer’s Association (NEMA) recommends that the instrument panel and cabinet be grounded. This power suppl y is equippe d with a three-conductor power cord; the third conductor b e ing the ground. The power supply is grounded only when the power cord is plugged into an appropriate receptacle. Do not operate this power supply without adequate cabinet ground connection.

Figure 2-4. Power Cord Plug Configurations

SHOCK HAZARD. Connect the power cord to a grounded receptacle before you connect any external floating voltages to the supply.

The offset pin on the standard three-prong power cord connector is the ground connection. If a two contact receptacle is encountered, it must be replaced with a properly grounded three-contact receptacle in accordance with the National Electrical Code, local codes and ordinances. The work should be done by a qualified electrician.

Line Voltage Conversion

You can change the supply to accept 100 V, 120 V, 220 V and 240 V ac input by adjusting the voltage selector card located inside of the line module (see Figure 2-3). After you have changed the line voltage, refer to Table 2-2 and check that the fuse inside the line module is the correct fuse for that line voltage. The procedure is as follows:

1. Turn off power and remove the power cord from the ac input socket on the back of the power supply.

2. To open the line module, move the plastic door on the module aside. If your line voltage change requires a change in the rating of the fuse, rotate FUSE PULL to the left and re move the fuse.

3. Grasp the voltage select pc board with a pair of needle-nose pliers and slide it out of its slot.

4. To select a voltage, orient the pc board so that the desired voltage appears on the top left side of the board. Push the board all the way back into its slot. The desired line vo ltage must be visible when the board is installed.

5. Install the correct fuse in the door of the line module if your line voltage change also requires a change in the rating of the fuse (see Table 2-2).

Installation28

FIRE HAZARD. Make sure the replacement fuse is one of the same type (size) and rating (amps) that is consistent with the voltage level you are operating at. Do not use a sub stitute fuse; use a fuse with the same Agilent Part number listed in Table 2-2.

6. Close the door of the line module and insert the power cord in the ac input socket. Your power supply is now configured to operate at the voltage you selected.

GP-IB Interface Connector

The GP-IB connector on the rear panel connects your power supply to your computer and other GP-IB devices (see Figure 2-2). Accessories (page 12) in Chapter 1 lists the cables and cable accessories that are available from Agilent Technologies. An GP-IB system can be connected together in any configuration (star, linear, or both) as long as the following rules are observed

1. The total number of devices, including the computer, is no more than 15.

2. The total length of all the cables used is no more than two meters times the number of devices connected together, up to a maximum of 20 meters.

Note IEEE Std. 488-1978 states that you should exercise caution if your individual cable lengths exceed 4 m.

Do not stack more than three connector blocks together on any GP-IB connector. The resultant leverage can exert excessive force on the mounting panels. Make sure that all connectors are fully seated and that the lock screws are firmly finger tightened. Do not use a screwdriver. Use a screwdriver only for the removal of the screws.

Installation

Getting Started

Introduction

This chapter is intended for the first time user o f t he supply. It provides four main discussions:

•

Front Panel Controls and Indicators

•

Turning on Yo ur Supply

•

Checking Out Your Supply Using Local Co ntrol

•

Introduction to Remote Operation

First, the supply’s front panel controls and indicators are briefly described. Some of the controls and indicators will be used

in the Turn On And Checkout procedures that follow. Chapter 6 describes how to use all of the front panel controls. Successful completion of the Turn On And Checkout procedures ensures with a high level of confidence that your supply is

operating properly. Complete performance testing and troubleshooting procedures are given in the Service Manual (Agilent Part No. 06626-90003).

The checkout procedures are performed locally from the front panel. In addition to checking the ope ration of your supply, these simple step-by-step checkout procedures will help the first time user become familiar with op e rating the supply from the front panel.

When you have completed the checkout procedures, you are then introduced to the fundamentals of operating the supply remotely from a computer. You will learn how to send a command to the supply from the computer and how to get da ta back to the computer from the power supply. A few of the most often used power supply commands will be described to help you get started and become familiar with the basics of programming your supply.

After completing this chapter, you can proceed to Chapter 4 to find out how to make load connections to your supply’s outputs and then to Chapter 5 (Remote Control) and/or Chapter 6 (Local Control) to learn all the details about operating your supply.

Front Panel Controls and Indicators

The power supply’s controls and indicators are shown in Figure 3-1 and are described in Table 3-1. Note that the front panel controls are identical for all mode ls except for the number of OUTPUT annunciators (nu mber 3 in Figure 3-1).

Getting Started

87613 5

6626A SYSTEM DC POWER SUPPLY

VOLTS AMPS

45.153 14.235m

1 2 3 4 CV CC UNR OCP ERR RMT ADDR SRQ

LINE

OFF

ENBLD-- OUTPUT --

LCL

SYSTEM OUTPUT ENTRY

ADDR

ERR

STO

RCL

RANGE V/I

OVSET

OCP

RESET

VOLT

CURR

OUTPUT

SELECT

VSET

ISET

OUTPUT

ON/OFF

789

456

123

9 4 2

Figure 3-1. Agilent 6626A Front Panel

Table 3-1. Controls and Indicators

Number Controls/Indicators Description Page

LCL key

Returns power supply to local mode (unless local

lockout has been received via GP-IB). Also, turns the

power supply’s display on if it was turned off via the GP-IB.

GP-IB Sta tus

Annunciators

(These three

annunciators indicate the

GP-IB status of the

RMT - Indicates that the power supply is operating under remote control (GP-IB)

ADDR - Indicates that the power supply is addressed to talk or to listen.

power supply).

SRQ - Indicates that the power supply is requesting

service.

OUTPUT

Annunciators

Indicate which output channel has been selected for front panel control and/or display (Only one output annunciator can be on at a time.)

Power Supply St atus

Annunciators

(These five annunciators indicate the status of the power supply).

CV - Indicates that the selected output channel is in the constant voltage mode.

CC - Indicates that the selected output channel is in the positive constant current mode ( + CC) o r the negative current limit ( - CC) mode.

3-13, 5-2, 6-1

3-13, 5-2, 6-1,

3-10, 5-1

5-1, 5-2, 5-3, 5-17

3-7, 3-8, 6-1--6-4

3-8, 4-1, 6-2, 6-3

ENTER

Getting Started

Table 3-1. Controls and Indicators (continued)

Number Controls/Indicators Description Page

4 (cont) UNR- Indicates that the selected output channel is

unregulated; i.e., it is not regulated by CV or CC control loops.

OCP ENBLD - Indicates that the overcurrent protection

function for the selected channel is enabled.

ERR - Indicates that a programming or hardware error

has occurred and that the ERR bit in the serial poll register has not been cleared

5 Alphanumeric LCD

Display (When power is

turned on, all segments will be displayed for approximately 2 seconds).

6 System Control Keys

(These four control keys affect the entire power supply and are independent of the

output selected.) ERR - Displays a programming or hardware error

STO - Used in conjunction with the numeric entry keys

The parameters stored in register 0 are the "power-up"

RCL - Used in conjunction with the numeric entry keys

Normal ly displays the me asured output voltage and

current for the selected channel. When programmed from the front panel, the function be ing programmed (e.g. VSET), the output channel (e.g. 2), and the present value (e.g. 2.250) will be displayed. Error conditions will be spelled out in alpha characters

ADDR - Displays the power supply’s GP-IB address. You can change the address using the numeric entry keys. You cannot query or change the address remotely (over the GP-IB).

message and clears the ERR bit in the serial poll register

to store the present output conditio ns for all outputs in the specified internal register (0-10). Each register stores the following parameters: VSET, VRSET, ISET, IRSET, and OVSET. In addition, register 0 also stores OCP, DLY, and MASK parameters. Register 0-3 are non-volatile.

parameters. These parameters are set upon applying AC power to the power supply. Note that the STO command cannot be used over the bus more than once per non-volatile register (0-3) without cycling the AC power (OFF and ON). However, these registers can be used for an unlimited number of times via the front panel keys without cycling the AC power .

to recall the settings from the specified internal register (0 to 10). All outputs are set to the recalled values.

4-4

3-8, 6-4, 5-13

4-4, 5-16

3-7--3-10,

4-4, 5-19, 5-20,

6-1--6-4

3-10, 5-2,

6-4

5-1, 5-20

5-1, 5-13

Getting Started

Table 3-1. Controls and Indicators (continued)

Number Controls/Indicators Description Page

Output Contro l K e ys

(These twelve keys are output dependent).

OUTPUT SELECT - Selects one of the output channels for local control or display. This key allows the channels to be selected in forward (Ð) or reverse (Ï) sequence.

VSET - Displays the selected output’s present voltage setting. The setting can be changed using the numeric entry keys, Ñ VOLT, or Ò VOLT keys..

ISET - Displays the selected output’s present current setting. The setting can be changed using the numeric entry keys, Ñ CURR, or Ò CURR keys.

OUTPUT ON/OFF - Toggles the selected output on and off. When off, "DISABLED’’ appears on the display.

OVSET - Displays the selected output’s overvoltage trip point. The setting can be changed using the numeric entry keys.

RANGE V/I - Displays the selected output’s full scale programming range for voltage and current. This key also enables the Up/Down keys to change the programming range.

Up/Down Keys - These keys increment or decrement the voltage or current settings of the output selected. The display will be in the metering mo de for the output selected. When one of the keys is pressed, it will change the output selected by one least significant bit (LSB). If the key is pressed and held, it wi ll continually change the setting until it is released The Ñ VOLT key is disabled when the supply is in the CC mode. The Ò CURRENT key is disabled when the supply is in the CV mode.

These ke ys will also allow you to change the programmed resolution range of voltage or current after the RANGE V/I key is depressed.

Ñ VOLT - Increases t he selected output voltage by an LSB and then a faster rate as the key is kept pressed, or after the RANGE V/I key has been pressed, sets the selected output to the high voltage range.

Ò VOLT - Decrease s the selected output voltage by an LSB and then at a faster rate as the key is kept pressed, or after the RANGE V/I key has been pressed, sets the selected output to the low voltage range.

3-7, 3-8, 6-1--6-4

3-8, 3-9, 5-9, 5-11, 6-2

3-8, 5-11, 6-3

5-12, 6-3

3-8, 5-12,

6-4

3-9

3-9, 6-2, 6-3

3-9

3-9, 6-2

Getting Started

Table 3-1. Controls and Indicators (continued)

Number Controls/Indicators Description Page

7 (cont)

Tab le 3-1, in addition to providing a brief description of each control and indicator, lists the paragraphs in which the use of

each control and indicator is described. Because most of the functions performed by the front panel controls can also be performed remotely by power supply commands, the corresponding paragraphs in Chapter 5 (Remote Operation) are listed in Table 3-1 where applicable.

Numeric Entry Keys

(These keys are used in conjunction wi th ma n y of the System Control and Output Control keys to enter the desired values into the power the metering mode. Supply.

LINE switch

Ñ CURRENT - Increases the selected output current by

an LSB and then at a faster rate as the key is kept pressed, or after the RANGE V/I key has been pressed , sets the selected output to the high current range.

Ò CURRENT - Decreases the selected output current by an LSB and then at a faster rate as the key is kept pressed, or after the RANGE V/I key has been pressed , sets the selected output to the low current range.

OCP - Toggles the selected output’s overcurrent protection circuit on and off.

RESET - This key performs the following:

1. Reset the selected output’s overvoltage crowbar (the

cause of the overvoltage must be removed before reset is successful) .

2. Reset the selected output’s overcurrent condition and returns the output to its previous settings (the cause of the overcurrent must be removed before reset is successful).

3. Return the display to the metering mode from any other mode (e.g. VSET). In the metering mode, the measured output voltage and current of the selected output are displayed .

0 to 9 - Set the value of the specified function and and (e.g. VSET 1 6.550 . Ï(backspace) - Erases the previous keystroke. Depressing this key without setting a value places the display in

ENTER - Enters the values on the display for the

specified function, initiates the function, and returns the display to the metering mode. Pressi ng this key without setting a value will result in retention of the previous values and returning the display to the metering mode.

Turns ac power on and off.

3-9, 6-3

3-8

3-8, 6-1--6-5

6-1

3-8, 6-1--6-5

3-6

Getting Started

Turning On Your Supply

The following paragraphs describe the power-on sequence which includes a self test of most of the power supply’s circuits. Before you turn on your supply, make sure that :

•

The line module on the rear panel is set to match your input line voltage.

•

The proper fuse is installed and the line cord is plugged in. If you have any questions concerning installation or p ower requirements, review Chapter 2. To turn on your sup ply, press the front panel LINE switch. When the power is initially applied, the supply performs a series

of self tests which last about 3 seconds. Included in these tests are checks of circuits on the GP-IB board and on each of the output boards.

Normal Self Test Indications

If the supply passes the self test, the display will first show all segments of the LCD display with annunciators on as illustrated in Figure 3-2.

Figure 3-2. Test Pattern of all Display Segments at Power-on

After all segments are displayed, the supply’s GP-IB address will appear for approximately 2 seconds as shown in Figure 3-

3. As shipped from the factory, the power supply’s address is set to 5. You must know this address before you can remotely program your supply.

Figure 3-3. Typical Address Display During Power-On Self Test

When self test is s ucces sfully completed, the power-up parameters stored in register 0 will be set (see page 89 for a

complete description of the store and recall functions). As shipped from the factory, this non-volatile register co ntains zero volts and zero current (see Table 5-4 on page 72) for all outputs. Note that the CV annunciator will indicate that the output is in the constant voltage mode.

Getting Started

Figure 3-4. Typical Display at Power-On

Self-Test Errors

If the supply fails the power-on self-test, all power supply outputs will remain disabled (off) and the display will indicate the type of failure and the output channel on which it occurred. Figure 3-5 shows that self-test detected an error in output channel 3. Error messages that could appear on the display if self-test fails are listed below. Self-test error messages are explained in Appendix D and troubleshooting procedures are given in the Service Manual. You may also call your Agilent Sales Office for help.

Power-On Self Test Error Messages HDW ERR CH "N"

8291 FAILED TIMER FAILED CV DAC CH ’’N" CC DAC CH "N" OV DAC CH "N" FUSE CH ’’N"

Note: "N" specifies the failed output channel number: 1,2,3, or 4 as applicable.

Figure 3-5. Sample Self-Test Failure Display

Checking Out Your Supply Using Local Control

The following procedures use the display and keys on the front panel to check each of your power supply’s outputs. No test equipment, other than a jumper wire (14 AWG), is required to perform these tests. The tests must be repeated for each output of your particular supply. The checkout consists of voltage, overvoltage, and current tests. It is assumed that power has already been turned on, the supply has passed the power-on self-test, loads are not connected to any of the supply’s outputs, and sense clips are connected between the sense terminals and the output terminals.

Note The following procedures are identical for all models and for all outputs. Use the OUTPUT SELECT key

to select an output to be tested. If an output fails any of t he tes ts, refer to the tro ubleshooting section in the Service Manual.

Getting Started

Voltage Test

1. Set the voltage of the selected output to 10 V by pressing:

VSET 1 0 ENTER

2. Check that the display reads approximately 10 V and 0 A and the CV annunciator is on indicating that the supply is in

the constant voltage mode o f operation.

Overvoltage Test

1. Program the overvoltage protection (OVP) to 19 V by pressing:

OV 1 9 ENTER

SET

2. Set the voltage to 16 V by pressing:

VSET 1 6 ENTER

3. Check that the display reads approximately 16 V and 0 A.

4. Set the voltage to 20 V by pressing:

VSET 2 0 ENTER

5. Check that the display reads "OVERVOLTAGE’’

6. Reset the supply by pressing:

VSET 1 6 ENTER RESET

7. Check that the display reads approximately 16 V and 0 A.

Current Test

1. Turn off the supply.

2. Remove the barrier block cover from the output to be tested and connect a short circuit (jumper wire) between the + V

and -V terminals of the output being tested.

3. Turn on the supply.

4. Use the

5. Set the voltage to a volts by pressing:

Set the current to 0.01 amps by pressing:

Getting Started

to select the output being tested.

VSET 5 ENTER

ISET . 0 1 ENTER

6. Check that the display reads approximately 0 volts and the programmable current limit value. Also, check that the front

panel CC annunciator is on indicating that the output is in the constant current mode of operation.

7. Set the current to 0.5 A by pressing:

ISET . 5 ENTER

8. Check that the display reads approximately 0 V and 0.5 A.

9. Enable the overcurrent protection circuit by pressing:

OCP

10. Check that the OCP ENBLD annunciator is on indicating that overcurrent protection is enabled and the display reads

’’OVERCURRENT ’’. When in overcurrent, the output is disabled.

11. Disable the overcurrent protection circuit by pressing:

OCP

12. Reset the output by pressing:

RESET

13. Check that the display reads approximately 0 V and 0.5 A.

14. Turn off the supply and remove the jumper from the output terminals.

Repea t the voltage, overvoltage and curre nt tests given on page 38 for the other output channel(s) using the

Changing Resolution Range

1. Press the RANGE V/I key.

2. Observe the selected output’s full scale programming range for voltage and current in the front panel display.

3. Press either the Ñ or the Ò key. (vo ltage or current)

4. Observe that the selected output’s full scale programming range for voltage and current changes to the high range (if the

Ñ key is pressed) or low range (if the Ò key is pressed). Note that no range cha nge will occur if the Ñ or Ò key is pressed while the supply is already in the requested range.

Introduction To Remote Operation

The following paragraphs explain the fundamentals of operating the supply remotely from a computer. Only a few commonly used programming commands will be discussed. Refer to Chapter 5 for a detailed description of all the commands. The intent of this discussion is to help first time users to quickly become familiar with op e rating their supply from a computer.

The programming examples that follow assume that a computer is connected to the GP-IB connector on the rear of your supply (see Chapter 2), power is applied, and loads are not connected to any of the supply’s outputs. The examples used are primarily for Agilent Series 200/300 computers using Agilent BASIC language. Read the manuals for your particular computer to find out which statements you must use.

key

Getting Started

Enter/Output Statements

The programming statements you use to operate your supply from remote depend on your computer and its language. In particular, you need to know the statements your computer uses to output and enter information. For example, the Agilent BASIC language statement that ad dresses the power supply to listen and send s the command to the power supply is:

OUTPUT

The Agilent BASIC language statement that addresses the power supply to talk and reads back data from the power supply

is:

ENTER

The supply’s front panel ADDR annunciator is on when the supply is addressed to talk or to listen.

Reading the GP-IB Address

Before you can operate your power supply remotely, you need to know its GP-IB address. The address was displayed during the power on sequence described in page 36. To see the address, press:

ADDR

A typical address display is shown in Figure 3-6:

The displayed response is the power supply’s GP-IB address. When sending a remote command, you append this address to

the computer’s GP-IB interface select code (normally 7). For example, if the select code is 7 and the power supply’s GP -IB address is 5, the combination is 705.

Changing the GP-IB Address

Note All examples in this discussion assume a GP -IB address of 5. It is recommended that you retain this

address to simplify programming.

Every device on the GP-IB must have an address. The supply’s address is factory set to decimal 5. Any address from 0 through 30 is a valid address. If you need to change the Agilent 662xA Supply’s address press:

You can now enter a new address. For example, press:

1 4 ENTER

You have now changed the address from 5 to 14. If you want to change the address back to 5, repeat the above procedure

but use 5 instead of 14 in the last step. No te that the address is stored in the power supply’s non-volatile memory and therefore will be retained through interruption o f the ac li ne power.

Figure 3-6. Typical Address Display

ADDR

Getting Started

Sending a Remote Command

To send the power supply a remote command, combine your computer’s output statement with the GP-IB interface select code, the GP-IB device address, and finally, the power supply command. For example, to set the output voltage of output channel 1 to 2 volts, send:

Getting Data From The Supply

The supply is capable of measuring the values of its output parameters in response to queries. In this example, the query asks the supply to measure the output voltage at output 1.

When you send a query from remote, the supply does not display the response as it did when you executed the command from the front panel. Instead, it holds the response in an output buffer. The output buffer is a register that holds information until it is read by the computer or is replaced with new information.

Note On an Agilent Series 200/300 Computer, the A variable must be declared before you do the following

steps. Refer to your computer’s o perating manual for more information.

Use your computer’s enter statement to get the response from the output buffer. For example, execute:

Followed by:

The ENTER statement enters whatever is in the supply’s output buffer into the computer’s A variable. The DISP statement

displays the A variable’s contents on the computer’s display.

Often Used Commands The command set contains over sixty commands that allow you to progra m the power supply in a variety of applications.

Within this command set, however, is a small subset of commands that are all you need for most applications. These commands are: VRSET, IRSET, VSET, ISET, VOUT?, IOUT?, OUT, OVSET, and OCP.

ENTER 705; A

DISP A

Getting Started

Each of these commands is briefly discussed in the following paragraphs to help you get started in programming your supply. To know more about these commands, refer to Chapter 5.

The VRSET and IRSET commands select the range the power supply operates in. Two ranges are available for each output

- standard resolution, and high resolution (see Table 1-2). If the value for voltage or current entered is not within the present ope rating range of the supply, the error annunciator will

indicate an error. Sending ERR?, and addressing the supply to talk, will return the error message (in the case ’’number range" error would be displayed.

Voltage and Current Programming. You can send voltage and current values to the power suppl y directly in volts or amps. The following examples use voltage and current values that are within the range of any output that the power supply provides.

To set the voltage of output 1 to 5 volts, send:

OUTPUT 705; “VSET 1,5”

To set the current o f outpu t 2 to 450 milliamps, send:

OUTPUT 705; ''ISET 2,.450"

Output Voltage and Current Measurement. The power supply has built-in metering circuitry, which allows it to monitor

the output voltage and current of the selected output. You can instruct the supply to return its present output voltage and current using VOUT? and IOUT? queries respectfully. The metering circuitry is auto-ranging, and will select the pro per resolution.

To mea sure the output voltage at output 1, send:

OUTPUT 705; "VOUT? 1"

To get the measurement from the output buffer, send:

ENTER 705; A

DISP A The computer should display a reading of approximately 5 volts . To measure the output current at output 2, send:

OUTPUT 705: "IOUT? 2''

To get the measurement from the output buffer, send:

ENTER 705; A

DISP A

Getting Started

Output On/Off. You can turn a specified output on or off. Individual outputs can be controlled as shown below. To turn off output 1, send:

OUTPUT 705; ’’OUT 1,0" When an output is turned off, it is set to 0 volts and to the minimum current limit value To turn on output 1, send:

OUTPUT 705; ’’OUT 1,1" When an output is turned on it will return to the voltage and current settings determined by the present VSET and ISET

values. Overvoltage Setting. You can send an overvoltage setting value to the power supply direc t ly in volts. If the output voltage

exceeds this setting, the output crowbar is fired, and the output voltage is quickly downprogrammed and disabled (0 volts output).

To set the overvoltage value of output 2 to 3.5 volts, send:

OUTPUT 705; “OVSET 2,3.5”

Overcurrent Protection. The output will go to the off state (0 volts and 0 current) when the overcurrent protection (OCP)

feature is enabled and the output is in the + CC mode. To enable the overcurrent protection mode for output 2 send:

OUTPUT 705; ''OCP 2,1" To disable the overcurrent protection mode for output 2, send:

OUTPUT 705; ''OCP 2,0" When overcurrent protection is disabled and the output is in + CC mode, the output current will be limited to and will stay

at the ISET value.

Returning the Supply to Local Mode

In the remote mode (RMT annunciator on), the front panel keys have no effect on an y of the suppl y's outputs and only the computer can control the supply. However, you can still use the front panel display to monitor the output voltage and current or check any of the present settings (VSET, ISET, OVSET, etc.) of the selected output channel.

If you want to use the front panel keys to chan ge the output settings, you must ret urn the supply to the local mode. You can return the supply to the local mode (provided that the local lockout command has not been received from the computer) by pressing the LCL key. A change between the local and remote modes (or vice versa) will not result in a change in the power supply outputs. Refer to Chapter 6 for additional details on using the LCL key and operating the supply in the local mode.

Getting Started

Output Connections and Operating Information

Introduction

This chapter explains how to make connections to the output terminals located on the rear of your power supply. Some general operating information is included in this chapter to help you und erstand how the power supply operates under various load conditions. This information ap plies whether you are operating the supply via the front panel or the GP-IB.

Output Ranges

Figure 4-1 identifies the output combinations that are available on the power supply. Each output can operate as a constant voltage (CV) or constant current (CC) source over a wide variety of output voltage and current combinations. In ad dition, each output has an active downprogrammer which operates at currents up to approximately 110% of the maximum positive current rating of the output. This means that each output can actively sink as well as source its maximum rated output current. At voltages below 2.5 V, a downprogramming resistor continues downprogramming until the voltage reaches approximately zero volts.

Figure 4-1. Output Combinations

Output Connections and Operating Information

Operating Quadrants

Figures 4-2A and 4-2B show the operating locus of your power supply in three quadrants. The area in quadrant 1 shows the operating locus defined by the voltage and current settings of each output. The area in quadrant 2 indicates the locus where each output can operate as a current sink. You cannot program current limit values in quadrant 2.

Output Connections and Operating Information

Figure 4-2. Typical Output Range Characteristics

Figure 4-3 shows the current sink characteristics lower voltages in greater detail. The area in quadrant 4 illustrates the

reverse polarity diode characteristics of each output. Do not operate any output with reverse-voltage currents that are greater than the maximum rating of the output.

Operating Ranges

Notice in Figure 4-2, there are four overlapping areas in quadrant one for both the 25 watt and 50 watt outputs. The Low Range Voltage and Low Range Current ranges are higher precision than the High Range Voltage and High Range Current ranges. The voltage and current ranges can be set independently (see page 73). If the high resolution range is programmed, attempting to program values outside this range will result in a number range error.

The 50 watt output (Figure 4-2B) is different from the 25 watt output (Figure 4-2A), in that there is a power limiting boundary at 1 amp in the High Voltage/High Current range. As a result, the 50 watt output can be set to no more than 1.03 amps at voltage settings above 16.16 volts, and vice versa.

Setting parameters of voltage or current beyond this power limit boundary, but within the High Voltage/High Current range will cause the other parameter (voltage or current) to automatically be scaled down to the power limiting boundary (see pages 71 and 73).

The voltage and current programming resolution of the outputs is affected by the setting of the range. The voltage of the 25 watt output, when programmed to the Low Voltage Range, has a voltage programming resolution of 460 µV. When programmed above 7 volts, the High Voltage Range must be selected resulting in a programming resolution of 3.2 mV.

The current of the 25 watt output, when programmed to the High Current Range, has a current programming resolution of 1 µA. When programming above 15 mA, the High Current Range must be selected, resulting in a programming resolution of 33 µA.

The voltage of the 50 watt output, when programmed to the High Voltage Range, has a voltage programming resolution of 1 mV. When programming above 16.16 volts, the high range must be selected, resulting in a programming resolution of 3.2 mV.

The current of the 50 watt output, when programmed to the High Current Range, has a current programming resolution of 13 µA. When programmed above 200 mA, the High Current Range must be selected, resulting in a programming resolution of 131 µA.

The readback range of the outputs is not programmable, and is selected automatically by the power supply.

Figure 4-3. Typical Downprogramming Characteristic Below 2.0 V

Output Connections and Operating Information

The readback resolution of the 25 watt outputs when metering voltages of 7 volts or below, will be 483 µV. For voltages

above 7 volts, the readback resolution will be 3.3 mV. The readback resolution of the 25 watt outputs when metering source currents of 15 mA or below, the readback resolution

will be 1 µA. When metering source currents above 15 mA, the readback resolution will be 48 µA. When metering sink currents of 15 mA or below, the readback resolution of the 25 watt outputs will be 1 µA. When

metering sink currents above 15 mA, the readback resolution will be 37 µA. When metering voltages of 16 volts, or below, the readback resolution of the 50 watt outputs will be 1.1 µV. For voltages

above 16 volts. the readback resolution will be 3.3 mV. When metering source currents of 200 mA or below, the readback resolution of the 50 watt outputs will be 14 µA. When

metering source currents above 200 mA, the readback resolution will be 160 µA. When metering sink currents of 200 mA or below, the readback resolution of the 50 watt outputs will be 14 µA. When

metering sink currents above 200 mA, the readback resolution will be 151 µA.

Protection Features

Protective circuitry within the supply can limit or turn off an output in the e vent of an abnormal condition. The activated protection feature can be determined by observing the front panel display area. You can also read back the status of the supply over the GP-IB. The following protection features are implemented:

OVERVOLTAGE -- shorts the output by firing an SCR crowbar and sets zero volts and minimal current on an output if any of the following conditions are present:

1. The output voltage exceeds the programmed overvoltage trip point.

2. The sum of the volta ge fro m the + V output terminal to the +S terminal plus t he voltage from the -S terminal to the -V

output terminal exceeds 10.0 V (applies to remote sensing only).

3. A trip signal is received on the output’s OV terminals.

4. The output’s fixed overvoltage circuit is activated. The OV trip point can be programmed up to 55 V. When an overvoltage occurs, the word OVERVOLTAGE appears in the

front panel display and the OV status bit is set for that output. Chapter 5 explains how to program the overvoltage trip level. A fixed overvoltage threshold of approximately 120% of the maximum rated output voltage is built into each output.

Because the fixed overvoltage circuit is biased from the output terminals, it can be activated and provide protection even when the supply is not connected to the ac power line. The OVRST command or front panel RESET key restores the programmed voltage and current values and clears the OV once the cause of the overvoltage has been eliminated.

OVERCURRENT -- when the overcurrent protection feature is enabled, and the output is sourcing current and enters the + CC operating mode, the output will be disabled (set to zero volts and minimal current) and the word OVERCURRENT will appear on the front panel display. In addition, the O C status bit is set for that output. The OCRST command or front panel RESET key restores the programmed voltage and current values and clears the OC once the cause of the overcurrent condition has been eliminated. Refer to Chapter 5 for p r ogramming details.

Output Connections and Operating Information

UNREGULATED OUTPUT -- the supply informs the user when output regulation is not guaranteed. This can occur when

attempting to sink excessive currents below 4 volts on 25 W outputs and 2 volts on 50 W outputs or when operating outputs in parallel. The UNR annunciator on the front panel and the UNR bit in the status register indicate that the specified output is unregulated. Line voltage dropout or an incorrectly set ac power module can also cause the output to become unregulated. If line voltage dropout continues, the supply shuts down and will return to the power-up condition when normal line voltage is restored.

OVERTEMPERATURE -- shuts do wn the linear pass transistors and downprogrammer of the output that has reached an unsafe operating temperature. Operation of the other outputs is unaffected. An overtemperature can occur because of excessively high ambient temperature, a blocked fan, or insufficient space at the sides for adequate air circulation. When an overtemperature condition occurs, the word OVERTEMP appears in the front panel display and the OT status bit is set. This circuit resets automatically and restores the output approximately 30 seconds after the temperature drops sufficiently for safe operation.

ERROR -- if the power supply receives an invalid command either through the front panel or the GP-IB, the ERR annunciator on the front panel comes on and the ERR bit in the serial poll register is set. The power supply does not execute the command and remains at previously set values. Pushing the ERR button in local mode displays the error message and clears the error. The error indicator may also indicate that an instrument failure has occurred. Refer to Appendix D for further details.

Connecting The Load

Each terminal block cover on the rear panel is secured by a locking tab which snaps into a slot at the left of the terminal block. To remove, insert a screwdriver into this rectangular slot and move the locking tab to the left. When the loc king tab releases, gently pull the terminal block cover away from the terminal block. To reinstall the cover, align it over the terminal block and gently press it in to position until the locking tab engages.

SHOCK HAZARD. Turn off ac power before making rear panel connections. All wires and straps

Each rear terminal block has six M3.5 x 0.6 x 6 mm screws for attaching wires (see Figure 2-2). Load connections to the

supply are made at the + V and -V terminals on each terminal block. Do not connect unterminated wires to the load terminals. Wires used for load connections must be properly terminated with termination connectors securely attached. Remember to replace the impact resistant plastic covers (Agilent P/N 06624-20007) over the terminal blocks after making connections.

Consistent with good engineering practice, all sense and trigger leads connected to the rear terminal blocks should be twisted and shielded to maintain the instrument’s specified performance.

Wire Size Selection

(ampacity) for various sizes of stranded wire.

Note that the minimum wire size required to prevent overheating may not be large enough to prevent OV trip when remote

sensing and to maintain good regulation. The load wires should be large enough to limit the total voltage drop in both leads to no more than 10 volts. See Figure 4-6 for total allo wed lo ad lead drop when programming to high voltage setti ngs. With remote sensing, load regulation is degrad ed 1 mV per 1 V in the - V output terminal load lead. (See Remote Sense Connections on page 52).

must be properly connected with terminal block screws securely tightened. Replace terminal block covers before reapplying power.

FIRE HAZARD Select a wire size large enough to carry short-circuit current without overheating. Two factors must be considered when selecting wire size for load connections: conductor temperature and voltage drop. To satisfy safety requirements, load wires must be heavy enough not to overheat while carrying the short-circuit output current of the unit. Table 4-1 lists the current-carrying capacity

Output Connections and Operating Information

Note To prevent tripping of the overvoltage circuit, pick a wire size sufficient to handle the FULL outp ut

current of the unit no matter what the intended load current or current limit setting.

Tab le 4-1 lists the res istivity for various wire sizes and the maximum lengths to limit the voltage drop to 1.0 volts for various currents.

Table 4-1. Stranded Copper Wire Ampacity and Maximum Wire Lengths to Limit Load Lead Voltage Drop

Wire Size 2 Wire Bundled 4 Wire Bundled Resistivity Drop to 1 V Per Lead

5 A 10 A 20 A

(AWG)

20 7.8 6.9 0.0102 20 10 5 18 14.5 12.8 0.0064 30 15 7.5 16 18.2 16.1 0.0040 50 25 12.5 14 29.3 25.9 0.0025 -- 40 20 12 37.6 33.2 0.0016 -- -- 30

(Cross Section

Area in mm

0.75 9.4 8.3 0.0267 7.4 3.8 1.8

Notes:

1. Ampacities for AWG wires are derived from MIL-W-5088B. Maximum ambient temp: 55°C. Maximum wire temp:

105°C.

2. Ampacities for metric wires are derived from IE Publication 335-1.

3. Ampacity of aluminum wire is approximately 84% of that listed for copper wire.

4. Because of wire inductance considerations, it is recommended that you keep your load leads twisted, tie wrapped, or

bundled together and less than 50 feet (14.7 meters) in length per lead.

5. See Page 49 for information on wire gauge considerations with capacitive loads.

Note The OVP circuit senses at the main output terminals and not on the sense leads. Thus, the voltage sensed

Load lead resistance is an i mportant factor relating to the CV stability of the supply with remote sensing of capacitive loads. If high capacitance loads are expected, you should not use wire gauges heavier than 12 to 14 AWG for long runs of load lead. See Figure 1-4 for more information about stability with output capacitors.

Multiple Loads

If you will be sensing the load locally (as shipped from the factory) and are connectin g multiple loads to one output, connect each load to the output terminals using separate connecting wires (see Figure 4-4). This minimizes mutual coupling effects and takes full advantage of the power supply's low output impedance. Each pair of wires should be as short as possible and twisted or bundled to reduce lead inductance and noise pickup.

If load considerations require the use of distribution terminals that are located remotely from the supply, connect the power supply output terminals to the remote distrib ution terminals by a pair of twisted or bundled wires. Connect each load to the distribution terminals separately. Remote voltage sensing is recommended under these circumstances. Sense either at the remote distribution terminals or, if one load is more sensitive than the others, directly at the critical load.

)

0.5 7.8 6.9 0.0401 5 2.4 1.2 1 12.7 11.2 0.0200 10 5 2.6

1.5 15.0 13.3 0.0137 14.6 7.2 3.6

2.5 23.5 20.8 0.0082 -- 12.2 6

by the OVP circuit could be as much as 10 V higher than the voltage being regulated at the load. Program the OVP trip voltage accordingly when using remote sensing. In addition, if the total voltage drop in both leads exceeds 10 V, a protective circuit will fire the OVP circuit regardless of the OVP setting.

Ampacity Per Wire (Amps)

(Ω/ft)

(Ω/m)

Max Length to Limit Voltage

(feet)

(meters)

Output Connections and Operating Information

Figure 4-4. Optimum Hookup for Multiple Loads, Local Sensing

Note When a load is connected through relay or switch contacts, contact bounce may activate the overvoltage

circuit and shut down the supply. Therefore, it is recommended that the output be downprogrammed to 0 or turned-off (disabled) before the relay (or switch) contact is opened or closed.

Positive and Negative Voltages

Either positive or negative voltages can be o btained from the supply by grounding (or "commoning") one of the output terminals. Always use two wires to connect the load to the supply regardless of where or how the system is grounded. This supply can be operated with any output terminal ± 240 Vdc (including output voltage) from ground.

Remote Voltage Sensing

The power supplies will allow up to a total load lead drop of 10 V. Because of the unavoidable voltage drop developed in the load leads, the as-shipped terminal block strapping pattern shown

in Figure 4-4 does not provide the best possible voltage regulation at the load. The remote sensing connections shown in Figure 4-5 improve the voltage regulation at the load by monitoring the voltage there instead of at the supply’s outputs terminals. This allows the power supply to automatically compensate for the voltage drop in the load lead. Re mote sensing is especially useful for CV operation with load impedances that vary or have significant lead resistance. It has no effect during CC operation. Because sensing is independent of other power supply functions, remote sensing can be used regardless of how the power supply is programmed. Note that with remote sensing, voltage readback monitors the load voltage at the se nse points.

Output Connections and Operating Information

The maximum voltage available at the power supply output terminals during remote sensing (see Figure 4-6) is 50.5 volts.

This allows the sum of the voltage acro ss both load leads to equal 10 volts maximum. For lower output voltages refer to Figure 4-3.

Remote Sense Connections

Remember to turn off the power supply before making or changing any connections on the rear panel terminal blocks. Connect the unit for remote sensing by first disconnecting the straps between sense and load terminals. Then make your connections as shown in Figure 4-5. Connect the sense leads as close to the load as possible. See wire size selection (pages 49 - 50) for information on selection of load lead wire gauge. Best results will be o btained by using the shortest load leads practical. It is recommended that you keep your load leads under 14.7 meters (50 feet) per lead because of inductance effects.

Figure 4-5. Remote Voltage Sensing

Output Connections and Operating Information

Figure 4-6. Total Allowable Load Lead Voltage Drop (total of both leads) with Remote Sensing

Output Noise Considerations

Any noise picked up on the sense leads will appear at the supply’s output a nd may adversely affect CV load regulation. Twist the sense leads or use a ribbon cable to minimize the pickup of external noise. In extremely noisy environments it may be necessary to shield the sense lead s. Ground the shield at the power supply end only; do not use the shield as one of the sensing conductors.

The noise specifications in Table 1-2 apply at the power supply output terminals when using local sensing. However, voltage transients may be produced at the load by noise induced in the leads or by load current transients acting on the inductance and resistance of the load lead. If it is desirable to keep voltage transient levels to a minimum, place an aluminum or a tantalum capacitor, with an approximate value of 10 µF per foot (30.5 cm) of load lead, right across the load (see Figure 4-5). Refer to Figure 1-4 for capacitive load stability considerations.

Programming Response Time with an Output Capacitor

Because voltage programming into an external output capacitor may cause the supply to briefly enter CC operating mode, voltage programming response time may be longer tha n that specified in Table 1-2. Use the following formula to estimate the additional response time:

Additional Response Time

Added Output Capacitor)(Charge in Vout

()

Current Limit Setting

Output Connections and Operating Information

Open Sense Leads

The sense leads are part of the supply’s feedback path. Connect them in such a way so that they do not inadvertently become open circuited. The power supply includes protection resistors that reduce the effect of open sense leads during remote-sensing operation. If the sense leads open during operation, the supply returns to the local sensi ng mode, with the voltage at the output terminals approximately equal to the programmed value.

Overvoltage Trigger Connections

Each output of your power supply has two OV terminals on its rear panel terminal block. These terminals are labeled +OV and -OV. By connecting the OV terminals all in parallel as shown in Figure 4-7, an overvoltage shutdown on any one output will also trigger the overvoltage on the remaining outputs. Any n umber of OV terminals up to eight sets can be strapped together. Observe polarity when connecting the OV terminals in parallel.

The overvoltage trip point for each output can be set either from the front panel or by remote programming. You can also externally fire the overvoltage circuit of one or more outputs by applying a 5 volt pulse of at least 50µs to any pair of OV terminals (see Figure 4-8). As long as all OV terminals are wired together, the outputs will be crowbarred simultaneously .

External Trigger Circuit

Figure 4-8 illustrates a reco mmended external circuit that can be used to provide an OV trip signal to the OV terminals. This circuit configuration provides good noise immunity and protects against the voltage pulse that is returned from the OV terminals every time that the overvoltage circuit fires. It can be operated from a wide range of bias voltages provided the input limiting resistors are chosen as tabulated in the figure. If it is not required to trip the OV with a TTL signal, then a bias supply, switch, current limiting resistor (R2), and protection diode are all that are required. Note that with the unit off (ac power removed), the + OV and - OV terminals are inactive.

The internal equi valent OV circuit is shown in Figure 4-9. Note the internal DC blocking capacitor, bleed resistor, and noise bypass capacitors.

Do not exceed 50 volts maximum between the + OV and the - OV terminals. The OV terminals are rated at ±240 Vdc (including external OV voltage) from chassis ground or any other output terminals.

Figure 4-7 Overvoltage Connections

Output Connections and Operating Information

Figure 4-9. Equivalent Internal OV Trigger Circuit

Power Supply Protection Considerations

Battery Charging If you are using your supply in a battery charging application, it is recommended that a series protection diode be added to

prevent damage to the supply during an overvoltage shutdown. Remember that each output has an overvoltage protection circuit that fires a crowbar to disable the output for any of the OVERVOLTAGE conditions described on page 48.

Figure 4-10 illustrates t he recom mende d connections and protection circuit for a b a ttery charging application. The diode will prevent damage to your supp ly that can result from excessive battery current flowing into the supply’s output in the event of an overvoltage shutdown.

Figure 4-8. External Trigger Circuit

Output Connections and Operating Information

Figure 4-10. Recommended Protection Circuit for Battery Charging

Capacitive Load Limitation

The programmable overvoltage protection circuit can be used to do wnprogram capacitive loads although it is primarily intended for use as a protection feature as described on page 48.

Repetitive (over 100 cycles) tripping of the overvoltage circuit with output capacitors greater than 2000

F may result in eventual damage to the supply.

Parallel Operation

Connect in parallel only outputs that have equivalent voltage and curr ent ratings.

Connecting outputs in parallel pro vides a greater current capability than can be o btained from a single output. Because each

output contains an active downprogrammer that is capable of sinking current from only ONE identical output, you can parallel no more than two outputs. These outputs must have equivalent voltage and current capability. For example, o n the Agilent 6626A power supply, only outputs 1 and 2 or 3 and 4 may be connected together. On the Agilent 6625A supply, none of the outputs may be connected together. If you are mixing different model supplies (i.e. an Agilent 6625A and an Agilent 6626A) be sure to connect only equivalent voltage and current outputs in parallel.

As an example, Figure 4-11 shows how to connect two outputs in parallel to a single load with local sensing. This configuration applies to both CV and CC operating modes. Connecting the load leads of output 2 directly to the + V and - V terminals of output 1 keeps the total length of the load leads to a minimum and reduces the number of wire connections that must be made at the load itself. Connecting the + S and -S terminals of output 2 directly to the sense terminals of output 1 compensates for the IR drop in the interconnecting load leads.

Output Connections and Operating Information

Figure 4-11. Parallel Connections with Local Sensing

CV Operation

For CV operation, one output must operate in CC mode and the other output must operate in CV mode. Although each output operates independently of the other, the output that is operatin g in CV mode will be ’’controlling" the voltage regulation of both outputs. Setti ng the output voltages as outlined in t he following par agraph and configuring the outputs a s shown in Figure 4-11 will allow output 1 to operate in CV mode and output 2 to operate in CC mode.

To assure that output 2 will be operating in CC mode, yo u must program output 2’s voltage to a hig her value than the voltage of output 1. One way to accomplish this is to first program output 2 to the maximum allowable voltage setting for the desired operating range (see Table 4-2 or Figure 4-2). These values are 1% higher than the rated voltage for the operating range. Then, program output 1 ’s voltage to the desired operating voltage. The lower voltage setting of output 1 will determine the voltage that appears across the load. The current limit point of the paralleled outputs is the sum of both individual current limit points. The output current of the parallel combination is the algebraic sum of the individual current readbacks.

The + OV and - OV terminals of output 1 should be wired to the + OV and - OV terminals of output 2. When programming the overvoltage setpoint, set both outputs to the same overvoltage value. When resetting the overvoltage, first disable both outputs by using the OUTPUT ON / OFF key or OUT comma nd. Next, reset both overvoltages. Finally, re-ena ble the outputs with the OUTPUT ON/OFF key or OUT command.

Table 4-2. Maximum Allowable Voltage Setting

Output Type Maximum Low Range Voltage Maximum High Range Voltage

25W 7.07V 50.5V 50W 16.16V 50.5V

Note Below 4 V on 25 W outputs and 2 V on 50 W outputs, the downprogrammer cannot sink the maximum

rated current. (See Figures 4-2 and 4-3). To operate parallel outputs at voltages under 2.5 V, program both outputs to the same voltage setting. Depending on the load, one output may operate in the unregulated mode.

Output Connections and Operating Information

CC Operation

For CC operation, set the output voltages as outlined in CV operation (page 57), or alternatively, program the voltage settings of both outputs to the same voltage limit point. Then program the current of each output so that the sum of both currents equals the total desired operating current. The simplest way to accomplish this is to program each output to one half of the total desired operating current. Both outputs will operate in the CC mode.

Remote Sensing

If it is necessary to remote voltage sense at the load, parallel the sense leads of outp ut 1 with the sense leads of output 2 and connect to the load as shown in Figure 4-12. The outputs can be programmed as previously described.

Figure 4-12. Parallel Connections with Remote Sensing

Specifications for Parallel Operation

Specifications for outputs operating in parallel can be obtained from the specifications for single outputs. Most specifications are expressed as a constant or as a percentage (or ppm) plus a constant. For parallel operation, the percentage portion remains unchanged while constant portions or any constants are changed as indicated below.

Current All parallel specifications referring to current are twice the single output specification except for programming resolution which is the same for bo th single output and parallel output operation.

Voltage All parallel specifications referring to voltage are the same as for a single output except for CV load effect, CV load cross regulation, CV source effect, and CV short term drift. Below 4 V on 25 W outputs and 2 V on 50 W outputs, these are all twice the voltage programming accuracy (including the percentage portion). CV load effect above 4 V on 25 W outputs and 2 V on 50 W outputs, could be twice the load effect specification for a single output. CV output noise for output voltages less than 4 V on 25 W outputs, and 2 V on 50 W outputs, may be slightly higher than the output noise for a single output.

Load Transient Recovery

Time

350 µs maximum to recover within 100 mV of nominal value following a load change within the range of 0 to full load.

Output Connections and Operating Information

Series Operation

SHOCK HAZARD. Floating voltages must not exceed 240 Vdc. No output terminal may be more

diode will conduct

Connecting outputs in series provides a greater voltage capability than can be obtained from a single output. Because the current is the same through each element in a series circuit, outputs connected in series must have equivalent current ratings. Otherwise, the higher rated output could potentially damage the lower rated output by forcing excessive current through it under certain load conditions.

Figure 4-13 shows an example of how to connect two outputs in series to a single load with local sensing. This configuration applies to both CV and CC operating modes. Connecting the + load lead of output 2 directly to the

- V terminal of output 1 completes the series connection between the two outputs. Connecting the + S terminal of output 2 directly to the - S terminal of output 1 and removing the sense jumper (between + S and + V) on output 2 compensates for the IR drop in the load lead from output 2 to output 1.

than 240 Vdc from chassis ground.

Connect in series only outputs that have equivalent curre nt ratings. Each output has a reverse voltage protection diode across its output terminals. The current conducted by this diode is not internally

limited by the output. Therefore, never connect an output in such a way that this

current in excess of the rated current of the output since damage could result.

Figure 4-13. Series Connections with Local Sensing CV Operation For CV operation, first program the current setting of each output to the desired current limit point. Then program the

voltage of each output so that the sum of both voltages equals the total desired operating voltage. The simplest way to accomplish this is to program each output to one half of the total desired operating voltage. Both outputs will operate in CV mode.

Output Connections and Operating Information

CC Operation

For CC operation, the current setting of each output must be programmed to the desired operating current. The sum of the voltage settings determines the vo ltage limit point. As an example, one way to program the voltage of the output is to set the voltage of each output to o ne half of the total voltage limit point. Then, at load voltages less than one half of the total voltage limit point, one output will operate in CC mode while the other output will be conducting through its i nternal reverse voltage protection diod e . At load voltages greater than one half the total voltage limit point, the output that was i n CC mode will change to CV mode while the output that was conducting through its diode will regulate the current in CC mode and provide the balance of the voltage required b y the load. Note that the total load voltage can be found by adding the results of reading back the indi vidual series outputs only when neither reverse voltage protection diode is conduc ting. When this diode is conductin g, the co rresponding output has reverse voltage acro ss it so that its voltage readback may not be accurate.

When an output is conducting through its reverse voltage p rotection diode, the output will have a reverse voltage across its output terminals with the - V terminal more positive than the + V terminal. This voltage will be maximum at the rated current of the output. (See Figure 4-2 for reverse diode characteristic). Note that when an output conducts through this diode, it will indicate CC mode even though it is not regulating the current or voltage. Also, note that the voltage readback is not specified to indicate negative voltages although it will operate down to a limit of about - 0.176 V on the 25 W outputs and -0.392 V on the 50 W outputs. These values will still be indicated even if the actual voltage is more negative.

Remote Sensing

If it is necessary to remote voltage sense at the load, connect the sense leads of output 1 and output 2 as shown in Figure 4-

14. Note that the + sense lead of output 2 must remain connected to the -sense terminal of output 1. The outputs may be set as previously described.

Figure 4-14 Series Connections with Remote Sensing Specifications for Series Operation Specifications for outputs operating in series can be obtained from the specifications for single outputs. Most specifications

are expressed as a constant or a percentage (or ppm) plus a constant. For series operation, the percentage portion remains unchanged while constant portions or any constants are changed as indicated below.

Output Connections and Operating Information

Voltage All series specifications referring to voltage are twice the single output specification

except for programming resolution which is the same as for a single output.

Current All series specifications referring to current are the same as for a single output except

for CC load effect, CC load cross regulation, CC source effect, and CC short term drift which are twice the current programming accuracy (including the percentage portion).

Load Transient Recovery Time

Bi-Polar Operation

Figure 4-15 shows an example connecting the outputs of the power supply for bi-polar operation to test power FET’s (PFET).

Great flexibility is achieved with this setup. The outputs of the po wer supp ly can be programmed as voltage or current sources provid ing positive or nega tive voltages o r currents. By takin g measurements via internal readback circuitry in the power supply, the outputs can be used as voltmeters or ammeters.

In order to properly measure the parameters of the PFET, it is desirable to be able to directly regulate any two of the bias parameters of the PFET, while being able to measure a third. The setup shown in Figure 4-15 allows control of Vds and Ids while measuring Vgs.

In this example, outputs 3 and 4 are connected to allow bipolar operation. Notice that the - S and - V leads, of outputs 3 and 4, are strapped together. The + S lead of V3 senses the voltage at the drain of the Device Under Test (DUT) and the + S lead of output 4 senses the voltage at the source of the DUT. Outputs 1 and 2 are strapped to sense the gate to source voltage.

Load transient recovery time is the same to within approximately twice the voltage setting band since the output impedances of the series combination add together.

Figure 4-15. Bipolar Operation

Output Connections and Operating Information

Remote Operation

Introduction

Chapter 3 introduced you to the basics of remote operation and provided a few simple examples using a Series 200/300 computer as the GP-IB controller. This chapter contains all the information required to control your power supply remotely and discusses in greater detail how each of the commands can be implemented. The material covered is intended for any controller capable of using the GP-IB interface functions mentioned in Interface Functions on page 63.

Four major sub-sections are discussed. These are:

1. GP-IB Operation

2. Programming Syntax

3. Initial Cond itions

4. Power Supply Commands

The GP-IB section briefly describes the GP-IB interface functions to get you acquainted with remote programming using

the GP-IB. Under Programming Syntax, the syntax of all commands, the numeric data formats and the programmable ranges for all models are given. Initial Conditions highlights the initial values of all the parameters at power-on. Power Supply Commands will describ e all the commands which can be used to program the supply’s functions including status reporting, error handling, protection features, and voltage and current programming. The power supply command s are summarized in Appendix C.

The examples are writte n in a generic form to make adaptation to your controller easy. Yo u should be familiar with the use of your controller and its instruction set and how the power supply commands can be incorporated in your controller commands. If you are not familiar with the operation of the power supply, you are advised to read through Chapters 2 through 4 first.

GP-IB Operation

Interface Functions

Remote control is i mplemented by the GP-IB. It enables instructions to be sent from an external computer equipped with a GP-IB interface. The power supply implements the following IEEE-488 Interface Functions:

SH1 - Source Handshake SR1 - Service Request AH1- Acceptor Handshake RL1 - Remote/Local T6 - Talker RL1 - Parallel Poll L4 - Listener DC1 - Device Clear

The source handshake, acceptor handshake, talker and listener functions are implemented by the interface circuits of the

power supply and the controller. The ADDR annunciator indicates when the power supply is addressed to listen or talk. (The talker function includes the Serial Poll, see page 64).

Service Request. This is a message which can be initiated by the power supply to request service from the controller. When the supply is requesting service, it asserts the service request (SRQ) line on the GP-IB to interrupt the controller providing the controller is configured to service interrupts. A service request can be generated whenever there is a fault on one of the outputs (up to 4 outputs), a programming error has occurred, or at power on providing certain commands are sent. Service request commands are discussed in detail in Service Request Generation on page 79.

The SRQ annunciator on the front panel display is turned on when the power supply is requesting service from the computer and remains on until the controller conducts a serial p oll. A serial poll removes the service request and turns off

Remote Operation

the SRQ annunciator regardless of whether the condition that caused the service request continues to exist. The service request is also removed when you send the " CLR’’ command (see page 76).

Remote/Local. The power supply can receive programming information either from the GP-IB (remote) or from the front panel (local). When the power supply is in remote, the state of the supply cannot be changed by using the front panel keys, although the LCL key will remain enabled. Remote operation takes precedence over local operation, hence if the supply is accepting commands remotely and you attempt to change it to local operation, the supply will not allow any local settings and will remain in remote. You can prevent the front panel from sending programming information by sending the local lockout command. This command is sent only from the GP-IB. If you change from local to remote or vice-versa, there will be no change in the programmed settings.

Parallel Poll. Parallel Poll allows the controller to receive at the same time one bit of data from each of up to eight instruments connected to the bus. Agilent power supplies designate bit #6, the RQS bit of the serial po ll register for this operation. By checking the status of this bit, the computer can quickly determine which instruments on the bus requested service. Once an instrument is identified, the computer can perform a serial poll to find out the exact cause of the request. Parallel Poll does not reset this service request bit (RQS) in th e power supply.

Note IEEE-488 does not define what data an instrument should put on a bus in response to parallel poll. Many

instruments such as Agilent Technologies power supplies indicate the state of their RQS bit, but the operator should not assume that all instrumen ts on the bus respond to parallel poll with their RQS bit.

Unless remotely configured, the power supply will respond with a 1 on one of the GP-IB data lines if it is requesting service and its address is between 0 and 7. Addresses 0 through 7 define which data line (1 through 8) the supply will respond on. If the address is set to 8 or greater, the supply will not respond unless remotely configured.

The power supply may be remotely configured to respond with a 0 or 1, on any of the data lines, to indicate that it is requesting service. This is done in accordance with IEEE-488 1978.

Serial Poll. In a serial poll, the controller polls each instrument on the bus one at time. The power supply responds by placing the contents of the eight-bit serial poll register on the GP-IB data lines. The Serial Poll register is discussed on page 78 and defines the function of each of the bits. After the serial poll, the service request is cleared and the SRQ annunciator at the front panel is reset (off). However, the cond ition that generated the service request may still be present. See page 79.

Device Clear. The Device clear command is typically used in systems to send all devices in the system to a known state with a single command. It may be implemented as an addressed or an unaddressed command. The power supply CLR command performs the same function as Device Clear (see page 76).

GP-IB Address Selection

You can find out the present address or change the address of the supply by using the front panel ADDR key as described in Chapter 3. Any address 0 through 30 is a valid address. If you program an address outside this range you will get a number range error.

Note Care should be taken to not select the co ntroller address.

Remote Operation

Power-On Service Request (PON)

The power supply can request service from the controller when the power is turned on. This request can be enabled or disabled by sending a PON command (see page 80). When the request is enabled, the supply can generate an SRQ at power-on or when there is a momentary loss in power. You can execute a serial poll to clear the service request. Table 5-7 details the conditions under which a PON command will generate an SRQ.

Note T he power supply has a non-volatile memory in which it stores certain system variables. Some of these

variables are the calibration constants, the present supply address, and the present setting of the PON command.

Programming Syntax

The following paragraphs describe the syntax of the device command that is used to program your power supply. As shown in Figure 5-1, the device command is a specific part of the program statement that your computer will accept. The first part of the statement is computer as well as programming language specific. Figure 5-1 shows the structure of a typical programming statement for an Agilent Series 200/300 computer. If you are using a different computer or programming language, refer to your computer programming manual to determine the correct syntax for this portion of the program statement. This section of the manual is only concerned with the device command portion (the part inside the quotes for Series 200/300 computers with BASIC) of the program statement.

Figure 5-1. Typical Program Statement for Series 200 Computers

Table 5-1. Power Supply Commands

Command Header Output

Channel

Query accumulated status register ASTS? 1, 2, 3, 4 --- Q2 Return power supply to turn on state CLR --- --- C1 Turn calibration mode on or off CMODE --- 0,1 (OFF,ON) C2 Query if calibration mode is on CMODE? 1, 2, 3, 4 See Table 5-4 Q1 Set the state of outputs at power on DCPON --- 0,1 (OFF, ON) CC+

Query outputs power on state DCPON? --- --- Set the reprogra mming delay time DLY 1, 2, 3, 4 0-32 C4 Query the setting of the delay time DLY? 1, 2, 3, 4 --- Q2 Turn front panel display on or off DSP --- 0,1(OFF,ON) C2 Display a string on front panel DSP --- ’’ST R I N G ’’ C6 Query if fro nt panel display is on DSP? --- --- Q1

Data Range

(Fig. 5-2)

2,3 (OFF, ON) CC-

Syntax

Remote Operation

Table 5-1. Power Supply Commands (continued)

Command Header Output

Channel

Query present hardware error ERR? --- See Table 5-8 Q1 Query fault register FAULT? 1, 2, 3, 4 --- Q2 Query the model number of supply ID? --- --- Q1 Program the I DAC in counts IDAC 1, 2, 3, 4 See Service Manual C4 Query setting of I DAC in counts IDAC? 1, 2, 3, 4 --- Q2 Send data to calibrate I circuits IDATA 1, 2, 3, 4 See Table 5-4 C5 Sets output to high I cal. value IHI 1, 2, 3, 4 See Table 5-4 C3 Sets output to low I cal. value ILO 1, 2, 3, 4 See Table 5-4 C3 Query measured I output IOUT? 1, 2, 3, 4 See Table 5-4 Q2 Used to Calibrate I readback circuits IRDAT 1, 2, 3, 4 See Table 5-4 C5 Set output to + I readback high cal value IRHI 1, 2, 3, 4 See Table 5-4 C3 Set output to - I readback high cal value IRHN 1, 2, 3, 4 See T able 5-4 C3 Set output to - I readback low cal value IRLN 1, 2, 3, 4 See Table 5-4 C3 Set output to + I readback low cal value IRLO 1, 2, 3, 4 See Table 5-4 C3 Set full scale current range of output IRSET 1, 2, 3, 4 See Table 5-4 C4 Query full scale current range ISET? 1, 2, 3, 4 See Table 5-4 Q2 Set current of an output ISET 1, 2, 3, 4 See Table 5-4 C4 Query current of an output ISET? 1, 2, 3, 4 See Table 5-4 Q2 Increase or decrease output current by value ISTEP 1, 2, 3, 4 See Table 5-4 C4 Select which output will be metered METER --- 1-4 C2 Query which output is being metered METER? --- --- Q1 Send data to calibrate -I readback NIDAT 1, 2, 3, 4 See Table 5-4 C5 Enable overcurrent protection OCP 1, 2, 3, 4 0,1 (OFF,ON) C4 Query if OCP is enabled OCP? 1, 2, 3, 4 --- Q2 Reset overcurrent protection OCRST 1, 2, 3, 4 --- C3 Turn output on or off OUT 1, 2, 3, 4 0,1 (OFF,ON) C4 Query if output is on or off OUT? 1, 2, 3, 4 --- Q2 Perform overvoltage calibratio n OVCAL 1, 2, 3, 4 See Table 5-4 C3 Reset overvoltage circuit OVRST 1, 2, 3, 4 --- C3 Set overvoltage trip value OVSET 1, 2, 3, 4 See Table 5-4 C4 Query overvoltage trip value OVSET? 1, 2, 3, 4 See Table 5-4 Q2 Enable power on service request PON --- 0,1 (OFF,ON) C2 Query if PON is enabled PON? 1, 2, 3, 4 --- Q1 Recall voltage and current settings RCL --- 0-10 C2 Set readback DAC to a number of counts RDAC 1, 2, 3, 4 See Service Manual C4 Query readback DAC count setting RDAC? 1, 2, 3, 4 --- Q2 Query revision date of ROM ROM? --- Q1 Query revision date of secondary ROM SROM? 1, 2, 3, 4 --- Q2 Set causes for generating a service request SRQ --- 01,2,3 C2 Query causes which will generate an SRQ SRQ? --- --- Q1

Data Range

(Fig. 5-2)

Syntax

Remote Operation

Table 5-1. Power Supply Commands (continued)

Command Header Output

Channel

Store present output state STO 0-10 C2 Query preset status of output STS? 1, 2, 3, 4 Q2 Perform self test on GP-IB interface TEST? . C1 Set bits in mask register UNMASK 1, 2, 3, 4 0-255 C4 Query bits set i n mask register UNMASK? 1, 2, 3, 4 Q2 Program the volta ge DAC in counts VDAC 1, 2, 3, 4 See Service Manual C4 Querys setting of voltage DAC in counts VDAC? 1, 2, 3, 4 Q2 Send data to calibrate the voltage circuits VDATA 1, 2, 3, 4 See Table 5-4 C5 Set output to high V calibratio n value VHI 1, 2, 3, 4 See Table 5-4 C3 Set output to low V calibration value VLO 1, 2, 3, 4 See Table 5-4 V C3 Query inputs of analog multiplexer VMUX? 1, 2, 3, 4 1-18 C4 Query measured value of an output VOUT? 1, 2, 3, 4 See Table 5-4 Q2 Calibrate the voltage readback circuitry VRDAT 1, 2, 3, 4 See Table 5-4 C5 Set output to V readback high cal value VRHI 1 2, 3, 4 See Table 5-4 C3 Set output to V readback low cal value VRLO 1, 2, 3, 4 See Table 5-4 C3 Set full scale voltage programming range VRSET 1, 2, 3, 4 See Table 5-4 C4 Query full scale voltage programming range VRSET? 1, 2, 3, 4 See Table 5-4 Q2 Set output voltage VSET 1, 2, 3, 4 See Table 5-4 Q2 Query se tting of output voltage VSET? 1, 2, 3, 4 See Table 5-4 Q2 Increase or decrease output voltage by value VSTEP 1, 2, 3, 4 See Table 5-4 C4

Figure 5-2 shows the possible syntax forms for the device commands that are used to program the power supply. Syntax

forms for the calibration commands that are discussed in Appendix A are also included. The oblong shape at the left of the syntax forms contains the command header which must be entered as shown in Tables 5-1 and 5-2. Commands are accepted in either uppercase or lowercase letters (ASCII characters). Circles contain characters that must be entered exactly as shown. Characters such as a space <SP> or a comma are used to separate elements in the command string. Characters such as a line feed < LF > or a semicolon are used to terminate the command string. Rectangles contain parameters that follow the command header lines and arrows indicate the correct paths through the syntax diagrams.

Numeric Data

The power supply will accept numeric data in implicit point, explicit po int, or scientific notatio n. A general syntax diagram for numeric data is included in Figure 5-2. Implicit point notation means that numbers do not contain a decimal point; integers for example. Numbers written in explicit notation contain a deci mal point, such as 12.35. In scientific notation, the letter E stands for "10 raised to". For example, 1.2E3 is read as 1.2 times 10 raised to the 3rd power, which equals 1,200. Plus and minus signs are considered numeric characters and are optional. If you program a number with an accuracy that is greater than the resolution of the supply, the number will automatically be rounded to the nearest multiple of the power supply’s resolution. Table 5-1 gives the ranges for numeric data that is sent to the supply.

The power supply will also return nu meric data (ASCII characters) to your computer. The format of the numbers returned depends upon the type of data requested. Table 5-2 gives the format for data returned to the computer in response to any of the queries that are listed.

Data Range

(Fig. 5-2)

Syntax

Remote Operation

Figure 5-2 (Sheet 1 of 2). Syntax Forms For Power Supply Commands

Figure 5-2 (Sheet 2 of 2). Syntax Forms For Power Supply Commands

Remote Operation

Table 5-2. Power Supply Queries

Query Header

(Note 7)

Voltage Setting VSET? 1,2,3,4 SZD.DDD(Note 3) 0(Note 8) Q2 Current Setting ISET? 1,2,3,4 (Note 2) 10 mA (Note 8) Q2 Full Scale Current Range IRSET? 1,2,3,4 (Note 2) High (Note 8) Q2 Full Scale Voltage Range VRSET? 1,2,3,4 ZD.DDD (Note 8) High (Note 8) Q2 Voltage Output VOUT? 1,2,3,4 SZD.DDD (Note 3) -- Q2 Current Output IOUT? 1,2,3,4 (Note 2) -- Q2 OVP Setting OVSET? 1,2,3,4 SZZD.DD 55 V (Note 8) Q2 OC Protection On/Off OCP? 1,2,3,4 ZZD -- Q2 Output On/Off OUT? 1,2,3,4 ZZD -- Q2 Unmask Setting UNMASK? 1,2,3,4 ZZD 0 (Note 8) Q2 Delay Setting DLY? 1,2,3,4 <sp>ZD.DDD .02 (Note 8) Q2 Status STS? 1,2,3,4 ZZD -- Q2 Accumulated Status ASTS? 1,2,3,4 ZD -- Q2 Fault FAULT? 1,2,3,4 ZZD -- Q2 Error ERR? -- ZZD -- Ql Service Request Se tting SRQ? -- ZZD 0 (OFF) Q1 Power-On SRQ On/Off PON? -- ZZD 0 (OFF) (Note 9) Q1 Display On/Off DSP? -- ZZD 1 (ON) Q1 Model Number ID? -- Agilent 662XA (Note

Selftest TEST? -- ZZD -- Q1 Calibration Mod e CMODE? -- ZZD 0 (OFF) Q1 DC Power On DCPON? -- ZZD 1 (ON) (Note 9) Q1

S = Sign Z = Digit with leading zeros put out as spaces D = Digit < sp > = space NOTES:

1. Output channels 3 and 4 are not used in all modes. (See Table 5-4).

2. Current is SZD.DDDDD (0.5 A) & SZD.DDDDDD (15 mA) SZD.DDDD(2 A) & SZD.DDDDD (0.2 A)

3. Voltage can be SZD.DDDD on 7 VR

4. "X" depends upon model.

5. A space is returned for a + sign.

6. All responses are followed by a <CR> and <LF> (EOI asserted with <LF>).

7. Spaces are allowed between the header and the question mark.

8. Unit powers up with values in state register 0. Table 5-3 gives initial factory settings.

9. Factory setting. P owers up to last stored value.

Order of Execution

When you send a set of instructions to the power supply, they are executed in the order in which they are received. The power supply completes the execution of the present command before executing another command. To send more than one command within the power supply command string, use a semicolon to separate the commands. This maximizes the rate at which the power supply accepts commands.

Terminators Terminators mark the end of a command string. As shown in Figure 5-2, the semicolon, line feed < LF >, and carriage

return line feed < CR > < LF > are the characters that indicate the end of a message to the power supply. When you are using the Agilent Series 200 computer with BASIC to send a command using the standard format (see Figure 5-1), the computer automatically sends < CR > < LF > on the data bus following the command.

Channel

(Note 1)

Response

(Notes 5 and 6)

Initial Value Syntax

(Fig.

5-2)

-- Q1

Remote Operation

Initial Conditions

Immediately after power on from the factory, the power supply automatically undergoes a self-test and sets all parameters to the values contained in Table 5-3. The values in the first part of the table come from storage register 0 and were stored at the factory. They will remain until STO 0 is used to change settings of the power on state. When the power supply is again turned on, it will initialize its output s to the values in storage register 0.

Table 5-3. Initial Conditions Parameter Inital Value Voltage 0 V High Range Current 10 mA High Range Reprogramming Delay 20 mS Store/Recall registers: 0-10: Voltage 0 V High Range Current 10 mA High Range Over Voltage (OV) 55 V (High Range) Over Current Protection (OCP) Disabled UNMASK register

SRQ 0 (Off) Output Channels On Front Panel Metering Output #1 Power Supply Address Last stored value (Factory set to 5) Local Control Enabled PON bit On PON SRQ Off (0) Cal Mode Off

Power Supply Commands

This section discusses the commands which yo u will use to program the supply’s voltage and current, protection circuits, and enhanced features like storage and recall registers, and reprogramming delay. When programming, you should be aware that the current, voltage and overvoltage ranges for each output of your supply may differ. Table 5-1 shows these values for the power supply. If you send values out of these ranges, you will get a number range error. A summary of all commands appears in Appendix C.

The output voltage of some output channels exceeds the safe operating limit of 42.2 V. To avoid any

tightened and terminal block covers are replaced before reapplying power.

Voltage Programming

To program voltage, send the output channel and the programmed value. In the example below, output l is programmed to 5 V.

The values you send must always be volts. For example if you want to program 450 mi llivolts, convert to volts and then send the command:

electrical shock, program the voltage to zero volts or turn off ac input power before changing any rear panel connections. Make certain all straps are properly connected, terminal block screws are securely

0 (cleared)

VSET 1,5

Remote Operation

VSET 1,.45

If the output cha nnel is operating in constant vo ltage mode (CV annunciator on) then the actua l voltage is the programmed

voltage, but in CC mode of operation (CC annunciator on), the programmed volta ge is the voltage limit for that output. When programming a value of voltage, the current setpoint will be changed if the total power is greater than the power

boundary (see Figure 4-2).

Example: ISET 4,1.5 sets current to 1.5 A VSET 4,50 sets voltage to 50 V

Sending the VSET command caused the current ISET to be reduced to 1.03 A. This is an example of power limiting

changing a supply setting. When this occurs, the "couple parameter" bit (see Table 5-5) in the status register is set.

Table 5-4. Programmable Output Range

Model

Output Configuration

6625A / 6628 A 6626A / 6629A

OUTPUT OUTPUTS Low 0-7 V 0-15 mA

(0.460 mV)

1 1 & 2 High 0-50 V 0-0.5 A

(3.2 mV)

OUTPUT OUTPUTS Low 0-16 V 0.2 A

(1.0 mV)

2 3-4 High 0-50 V 0-2 A

(1,2-6628A) 1,2,3,4-6629A) (3.2 mV)

* The maximum programmable voltage values for each range are 1% higher than the rated voltage and the

maximum programmable current values for each range are 3% higher than the rated current.

** Each channel wakes up to values stored in state register 0. The factory set values are shown in the first

part of Table 5-3. All other registers are set to these settings. Vo latile registers 4-10 always power-up to these conditions.

To readback the programmed voltage setting for output 1, send the query:

and address the supply to talk. If you want to know the value of the actual output voltage of output 1, send the query:

The results are placed on the GP-IB and read into the controller when the supply is addressed to talk.

Note T he power supply will round the VSET and ISET settings to the nearest multip le of their resolution.

Table 5-4 lists the average resolution of these settings.

Operating

Range *

VSET? 1

VOUT? 1

Output Volt

(Avg. Res.)

Output Curr **

(Avg. Res.)

(1 µA)

(33 µA)

(13 µA)

(131 µA)

Remote Operation

Current Programming

To program the current, send the output channel and the programmed value in amps. In the example below, output 1 is programmed to 15 mA.

ISET 1,0.015

The value you send must always be i n amps. For examp l e if you want to program 95 milliamps, convert to amps and then

send the command

ISET 1,.095

If the output channel is in constant current (CC) mode of operation, then the actual current is the programmed current but if

the output is in the CV mode, the programmed current is the current limit of that output. When programming a value of current, the voltage set point can be changed if the total power is greater then the power

boundary (see Figure 4-2).

Example: VSET 4,50 Voltage set to 50 V ISET 4,2 ISET to 2 A

Sending the ISET command caused the VSET to be reduced to 16.16 V. This is an example where power limiting changes

a supply setting. When this occurs, the "c oupled parameter" bit (see Table 5-5) in the status register is set.

To readback the programmed current for output 1, send the query and addressing the supply to talk.

ISET?

You can also instruct the supply to measure the actual output current at output channel 1 by sending the following query

and address the supply to talk.

IOUT? 1

The results are placed on the GP-IB and read into the controller.

Range Programming

The range can be set by using the VRSET or IRSET commands. The power supply will automatically pick the range that the value sent will fit into.

Examples: VRSET 1,7 will select the 7 V range VRSET 1,3.2 will select the 7 V range VRSET 1,9.0 will select the 50 V range VRSET 1,50.5 will select the 50 V range IRSET 1,.015 will select the 15 mA range IRSET 1,0 will select the 15 mA range IRSET 1,.020 will select the 0.5 A range IRSET 1,0.1 will select the 0.5 A range

Note Ranges will accept values up to 1% greater then full scale for voltage and 3 % for current. Larger

numbers will generate a number range error(s).

When going from the high range to the low range, the present setting must be within the boundary of the low range or the setting will be reduced to the maximum of the low range. If the setting is changed the "couple parameter" bit (see Table

5-5) in the status register will be set to indicate the change.

Remote Operation

Output On/Off

The OUT command disab les/enables an output channel of the power supply. It will not disturb any other programmed function nor will it reset the protection circuits. You can control individual ou tputs with the OUT command as shown below. For example, to disable output channel 1 send the following:

OUT 1,0

To enable outp ut channel 1 send the following command

OUT 1,1

You can find out the present state of output 1 by sending the query:

OUT? 1

and addressing the supply to talk. The response from the supply is either a "0" to indicate output 1 is off or a "1" to indicate

that the output is on. When disabled, the output behaves as if it were programmed to zero volts on the high voltage range and 10 mA o n the high current range.

Overvoltage (OV) Protection

The programmable OV is a protection feature which can be set by the operator to protect the load against excessive voltage. When the actual voltage exceeds the programmed overvoltage setting for a given output channel, the OV is tripped. The OV circuit will fire the SCR crowbar which shorts across the output and the output assumes a low impedance state.

For example, to program the OV of output channel 1 to 9.5 V send the following command:

OVSET 1,9.5

To find out the OV setting for output channel 1 send the following query and address the supply to talk:

OVSET? 1

To enable an outp ut after it went into overvoltage, you must first remo ve the overvoltage condition and then send the OV

reset command.

To reset output 1 send:

OVRST 1

If you send the reset command without first removing the OV conditio n, the supply will fire the OV again.

Note If the programmable OV fails, the supply has a fixed OV circuit which will fire the SCR crowbar if the

voltage exceeds 120% of the maximum rated output. The fixed OV circuit will also fire the SCR crowbar if the supply is off (line cord disconnected) and an external source is supplying voltage which exceeds 120% of the maximum rated output.

Remote Operation

Overcurrent Protection (OCP)

The OCP is a protection feature employed by the power supply to guard against excessive output currents. When the output enters the + CC mode and the OCP is enabled, the OCP circuit down programs the output voltage and disables the output.

To enable the OCP, for output channel 1, send the command

OCP 1,1

To disable the OCP, send the command

OCP 1,0

You can find out the OCP setting by sending the following query and addressing the power supply to talk.

OCP? 1

The response from the power supply is either a "0’’ to indicate that O CP is off or a ’’1" to indicate that it is on. To reset the

output channel after an overcurrent trip, you can either disable the OCP and send the reset command, or you can reduce the output current below the programmed current and then send the reset command. To reset output 1, send the command:

OCRST 1

Note The supply can re port a fault cond ition when an output is in overvoltage or overcurrent. Alth ough the

OVRST and OCRST commands re-enable the output, they do not clear the fault register. As a housekeeping measure, it is advisable to always clear the fault register by querying its value after an OV or OC reset.

Multiple Output Storage & Recall

The power supply has 11 internal registers (0-10) each of which can store the voltage and current settings of all the outputs. By storing voltage, volta ge range, current, current range and OV settings for all outputs and recalling them later, you can have significant savings in programming time. (See Supplemental Characteristic s in Table 1-2). Upon shipment from the factory, registers (1-10) contain values of 0 volts and 0 current (see Table 5-4).

Registers 0-3 are non-volatile. The y are limited to one STORE each. If more than one STORE is attempted, error 30 (STORE LIMIT) will result. The line must be turned off/on to re-enable these store locations. Register 0 is a special case that also contains Delay, Mask. When the power supply is turned on, it will access register 0 for power-up settings. Registers 4-10 (volatile) will be reinitialized to 0 vo lts and 10 mA (max OV & V, I ranges = HIGH) when power is cycled on/off.

To store voltage and current settings, issue the store (STO) command and specify a register (0-10). For example, to store the present setting of current and vo ltage of all outputs in register 2, send the following command:

STO 2

To set the power supply to the voltage, voltage ra nge, current, current r ange, and overvoltage settings stored in a register,

issue the recall (RCL) command followed by the desired register. For example to recall settings stored in register 2, send the following command:

RCL 2

When a register is recalled, the o utputs will be set sequentially (output 1, output 2, etc.). If you attempt to recall a register

outside the 0 to 10 range, you will get a number range error (GP-IB code 5 in Table 5-8).

Remote Operation

The Clear Command

This command will return the power supply to its power-on state and all parameters are returned to their initial power-on values except for the following:

1. The store/recall registers are not cleared.

2. The power supply remains addressed to listen.

3. The PON bit in the serial poll register is cleared

To clear the power supply, send the following command:

CLR

Status Reporting

The power supply has the ability to report its internal stat us to the user whenever it is asked to do so . Depending on the type of status the user requested, the supply will interrogate the status, accumulated status, mask, or fault registers present in each output. The status register can report status independently (see page 76) or it can work together with the mask and fault registers to report a fault (see page 77). The accumulated status register records every status condition the output experienced since the time it was last read (see page 77). Figure 5-3 shows a conceptual model of the operation of these registers.

The supply has one serial poll register which services all outputs and provides the user with other power supply statusrelated information as discussed in page 78.

Status Register. Each output channel of the power supp ly maintains its present status in an eight bit register. This status register reports the status of the output c hannel whenever it is queried. A "1" in any of the bit positions indicates that the condition is true. As long as the cond ition continues to be true, the bit will remain set. Assignments for the b its are shown in Table 5-5.

Decoding of the reading is based on the weighted number placed on each bit of the eight bit status registers. For example, bit position 5 in the register has a bit weight of 32 (see Table 5-5). Each bit is assigned to a particular condition and the corresponding bit weight is used to identify that condition. When set, bit 5 indicates that the associated output is in the unregulated state. If this is the only bit that is set, the number 32 will be returned when the output’s status register is queried.

Remote Operation

Figure 5-3. Functional Relationship of Status Registers

Table 5-5. Bit Assignment for the Status, Astatus, Fault, and Mask Registers Bit Po sition 7 6 5 4 3 2 1 0 Bit We ight 128 64 32 16 8 4 2 1 Meaning CP OC UNR OT OV -CC +CC CV Where

CV = Cons tant Voltage Mode + CC = Positive Constant Current Mode

- CC = Negative Current Limit Mode OV = Overvoltage Protection circuit tripped OT = Over Temperature Protection circuit tripped UNR = Unregulated Mode OC = Over Current Protection tripped CP = Coupled parameter (See Note)

Note: When the range is switched as discussed on page 73, or the power limit is exceeded (see pages 71 &

73), the CP bit is set. It is cleared when you send a voltage, current or range value that causes no other changes.

To query an output cha nnel for its status, you must specify the output channel. For example, to find out the status at output 2 send the following query and address the supply to talk:

STS? 2

Accumulated Status Register. Each output chan nel of the power supply also maintains a cumulative status i n its

accumulated status (astatus) register. This register records every status condition the power supply output entered since it was last queried. When queried, it returns a decimal number which is decoded as shown below. The astatus register is reset to the present value of the status register after it is queried. The bits are assigned as in Table 5-5. Here is an example to help you decode the decimal number (from 0 to 255) returned when the astatus register is queried. If the output channel was in overvoltage since the last reading of the astatus register and that channel is presently operating in constant voltage mode, the reading you will get when you query the register will be 9. To decode this we use Table 5-5.

9 = 8 + 1

OV + CV For example, to query the astatus register of output 2, send the following query and address the supply to talk

ASTS? 2

The Mask and Fault Register. The fault register works in conjunction with the mask register. These are two eight bit

registers which report any fault cond ition on a particular output channel. The mask register is used to set up the conditions that generate a fault which is latched in to the fault register. The user can then read the fault register to determine the fault. When a bit in the fault register is set, the power supply can generate a service request for that output providing the service request command on fault (SRQ 1 or SRQ 3) was previously sent. See page 79 for a discussion on service request.

To understand how these two registers work, we must include the status register in this discussion. Recall that the status register takes its input from the power supply and the user cannot chan ge its contents. The mask register takes its inp uts from the user, and the power supply cannot change its contents. The fault register takes its inputs from both the mask and the status registers. You can find out the setting of the mask register of output 2 by sending the following query and addressing the supply to talk:

UNMASK? 2

The response will be a numeric code between 0 and 255 which can be decoded by consulting Table 5-5. You can set the

conditions to generate a fault by setti ng (unmasking) one or more bits in the mask register. The conditions will remain unmasked until you change them. To unmask conditions i n o utp ut 2 for example, send the following command:

Remote Operation

UNMASK 2,XXX

where XXX specifies the numeric code (0 to 255) for the unmasked conditions (see Table 5-5). If during operation, the

output experiences any of the previously unmasked conditions, it will set the correspondin g bit(s) in its fault register. Remember that the bits in the fault register can be set when there is a change in either the status register or the mask

register. Each output has its status, mask, and fault registers arranged as shown in Figure 5-3 and Table 5-5. The mask register, which is set by the user, is used to specify which bits in the status register are enabled (unmasked) to set bits in the fault register. A bit is set in the fault register when the corresponding bit in the status register changes from ’’0’’ to ’’1’’ a nd the corresponding bit in the mask register is a "1". Also, if a bit in the status register is already set and then the corresponding bit in the mask register is set (unmasked), the corresponding bit in the fault register will be set.

In addition, if both status and mask register bits remain set after the fault regi ster was read (and cleared), the fault register will remain cleared as long as there are no changes in either the status or mask registers with the following exception. Executing a VSET, ISET, RCL, OVRST, OCRST, or OUT on/off command, will cause the CV, + CC, - CC, or UNR bit (as applicable) in the fault register to be set. Note that the fault register is cleared immediately after it is read.

As shown in Figure 5-3, if one or more bits in the fault register of a given output channel are set, then the FAU bit for that output in the serial poll register will also be set and a service request may be generated (see page 79). To read the fault register of output 2 and find out which bits are set, send the following query and address the supply to talk:

FAULT? 2

The power supply responds with a number which can be decoded from Table 5-5. For example, the number 9 (8 + 1)

indicates that the OV and the CV bits in the fault register are set.

Note If the condition(s) generating the fault(s) is (are) removed but the fault register is not read, the bit(s) in the

fault register will remain set.

The Serial Poll Register. The serial poll register is an 8 bit register which the supply uses to keep track of its internal operating status and to determine the operating status of each of its outputs. Table 5-6 defines each bit.

Table 5-6. Bit assignment of the Serial Poll Register Bit Po sition 7 6 5 4 3 2 1 0 Bit We ight 128 64 32 16 8 4 2 1 Meaning PON RQS ERR RDY FAU 4 FAU 3 FAU 2 FAU 1

The first four bits (0 to 3) in the register tell whether or not a particular output has a fa ult. If t here is a fault in one of the

outputs, then the corresponding FAU bit will be set. Thus if output 1 has a fault, then FAU 1 will be set. In models with only three outputs, FAU 4 will always be zero and in two o utput models, FAU 3 and FAU 4 will always be zero.

The RDY bit is set when processing is complete and is cleared when the supply is processing commands. The ERR bit is set when a programming or hardware error occurs and is cleared when the error query (ER R? ) is received.

The error annunciator on the front panel informs the user when this bit is set or cleared.

The RQS bit is set when the power supply generates a service request and cleared after a serial poll is done (see page 79). The PON bit is set at power on and cleared when a CLR command is sent.

Remote Operation

Service Request Generation

When operating your supply, you may want it to request service every time a fault or a programming error condition occurs. To do this you send a service request (SRQ) command. When the condition is true, the power supply responds by setting the RQS bit in the serial poll register, setting the SRQ annunciator on the front panel, and issuing an SRQ o ver the GP-IB.

The power supply can generate a service request for any of the following reasons: (refer to Table 5-7)

•

An Output Fault. If there is a fault on one or more of the output channels and you previously sent the SRQ 1 or

SRQ 3 command (see Service Request Enable/Disable information below), then an SRQ will be generated.

•

An Error . If there is an error (see Tables 5-8) and you previously sent the SRQ 2 or SRQ 3 command, (see

Service Request Enable/Disable information below), then the supply will generate a service request.

•

Power-on. At power-on, the PON bit of the serial poll register is set but the supply will only generate an SRQ if

you previously sent a PON 1 command.

•

Input Line Voltage Dropout. Same as power-on cond ition.

To find out the nature of the service request, you must do a serial poll. This will isolate the output that generated the request

by checking which of the FAU bits are set in the case of a fault, or checking to see if the error bit is set in the case of an error. If the SRQ on faults was set, then send the fault q uery.

FAULT? 2 (using output 2 as an example)

and address the supply to talk if you want to find out which of the conditions you unmasked in Figure 5-3 are true. For

example if the supply was in overvoltage and that condition was unmasked then the response from the fault query will be "8’’ (see Table 5-5).

Note When you query the fault, the fault register is cleared. Performing a serial poll will reset the RQS bit but

will not clear the fault register.

If the SRQ on error was set then you can send the error query ERR? and address the supply to talk. The response will identify the error by its code (see Table 5-8).

Service Request Enable/Disable. You can query the status of the service request enable/disable function by sending the query:

SRQ?

and addressing the power supply to talk. The response from the supply is one of the following:

0, 1, 2, or 3 0--indicates that the service request capability (except for power-on; see page 80) is disabled. 1--indicates that it is enabled for output fault conditions. 2--indicates that it is enabled for error conditions. 3--indicates that it is enabled for both fault and error conditions.

Remote Operation

The ability to generate service requests can be enabled or disabled using the SRQ command as described below. To disable the service request capability, except for power-on, send:

SRQ 0

To enable the service request capability for all output faults, send:

SRQ 1

To enable the service request capability for errors, send:

SRQ 2

To enable the service request capability for both faults and errors, send:

SRQ 3

The Power-On Service Request. You can also cause the power supply to request service every time it is switched on

or every time there is a temporary loss in power. To do this send the following command:

PON 1

If you want to disable this facility, send the command.

PON 0

If you want to find out if the power-on SRQ is enabled or disabled, send the following query:

PON?

and address the supply to talk. The supply will respond with a 1 or 0 as discussed above.

Note The power-on (PON) SRQ mode is stored in the non-volatile memory of the supply so that although the

supply may be switched off, it will remember the status of the last PON command at power-on and respond accordingly.

Table 5-7 summarizes all the co nditions under which a service request will be generated.

Table 5-7. Conditions for Generating a Service Request

Condition Commands Sent State of

• Any

• Power-on

• Error

• Fault

PON SRQ

0 0 0 1 - 1

- 2 or 3 1

-1 or 3 1

RQS Bit

Reprogramming Delay

The power supply may switch modes or become unregulated momentarily after a new output value is programmed. Because of their short duration, these cases may not ordinarily be considered a fault but the supply will recognize this deviation and generate a fault signal. To prevent this, the reprogrammin g d e lay feature is implemented.

Remote Operation

Reprogramming delay will delay the onset of certain fault conditions and prevent the power supply from registering a fa ult when these conditions are true. When the delay is in effect, the CV, + CC, - CC and UNR bits of the status register are masked and cannot communicate with t he mask and fault registers and the OCP function. This will prevent the supply from registering a fault should any of these bits become set during the delay period. Reprogramming delay is initiated when any of the following functions are executed:

VSET, ISET, RCL, OVRST, OCRST, OUT on/off

At power-on reprogramming delay is set to 20 mS. You can specify new values between 0 and 32 S in steps of 4 mS. If you specify a value which is not a multiple of 4 mS, the suppl y will round off the set value to the nearest 4 mS multiple.

To program a new value of 80 mS in output 2 for example, send the following:

DLY 2,.08

If you send a value outside the 0 to 32 S range you will get a programming error. You may use the programming response times in the specifications table to give you an id ea of a typical delay setting. However, the appropriate delay setting will also depend on load capacitance, load resistance, and current limit setting. See page 53 for output capacitor considerations.

To query the reprogramming delay setting of a particular output channel, send the following query:

DLY? 2 (using output 2 as an example)

and address the supply to talk. The response will be a n umeric value between 0 and 32.

Display On/Off

When the display is on, the commands sent across the GP-IB may experience a slower processing time because the processor must also spend time to monitor the outputs and update the display. You can shorten your command processing time by turning off the display. To turn off the display, send the command :

DSP 0

To re-enable the display send the command:

DSP 1

You can also find out the status of the display by sending the following query and addressing the supply to talk:

DSP?

The response will be either a "1’’ or a "0’’.

Message Display Capa bility. The display command can also be used to display messages on the front panel. Messages may consist of a maximum of twelve alphanumeric characters. Only upper case alpha characters, numbers, and spaces will be displayed.

For example, to display the message "OUTPUT 2 OK", send the following command:

DSP "OUTPUT 2 OK’’

Note The BASIC programming statement for a series 200/300 computer would be as follows:

OUTPUT 705; "DSP""OUTPUT 2 OK"""

Remote Operation

Other Queries

In the examples discussed above, you saw how to use queries for each function discussed. The following paragraphs describe other queries which were not previously covered.

ERROR Query. The power supply can detect both programming and hardware errors. You can use either the front panel (see page 89) or the GP-IB to find out the type of error. Upon detecting an error, the error annunciator on the front panel and the ERR bit in the serial poll register will be set. When in local mode the supply will display the error name in response to pressing the ERR key on the front panel. Over the GP-IB, only the error code will be returned. After a query, the error bit is cleared. A description of these codes is given in Tables 5-8. To find out what the error is, send the following query and address the supply to talk:

ERR?

The supply will respond with an error code number (see Table 5-8). ID Query. If you want to know the model number of the power supply you are working with, you can send the ID? query

over the GP-IB. To do this send the following over the GP-IB and address the supply to talk.

ID?

The supply will respond with its model number. Test Query. You can get the power supply to perform a limited self-test at any time during its operation by sending the

TEST? query over the GP-IB. This test does not affect the analog control circuits of the supply and it can be performed while the outputs are connected to external circuits. For tests of the analog control circuits refer to Chapter 3. Responses to the test query are described in Table 5-9. This test cannot be done from the front panel. To instruct the power supply to carry out a self-test, send the following query and address the s upply to talk:

TEST?

Calibration Mode Query. To be able to calibrate your power supply, the calibration mode (CMODE) must be turned on (See Appendix A for a detailed description of the calibration pr ocedure). To find out if the CMODE is on or off, send the following query over the GP-IB and address the supply to talk:

CMODE?

The supply will respond with a ’’1" which indicates that CMODE. is on or a "0" which indicates that CMODE is o f f.

DCPON. The DCPON command sets the state of all outputs at power-on. You can specify if the outputs wake up enabled or disabled when the unit is turned on. To enable all outputs at turn-on send:

DCPON 1

To disable all outputs at turn-on send:

DCPON 0

Note that these commands set the output voltage to zero and the output current to a slightly positive value when the OUTPUT OFF command is issued. Therefore, the constant voltage feedback loop is active and the outputs are in constant

voltage mode when programmed “OFF”.

Starting with firmware revision A.00.04 and later, two additional commands let you set the output current to a slightly negative val ue when the OUPU T OFF command is issued, causing the outputs to be in constant current mode when programmed “OFF”. The benefit of being in constant current mode when the output is off is that if the load impedance and the voltage and current settings are suc h that the unit is forced into constant current mod e at turn on, then the current feedback loop will be active during the transition to OUTPUT ON, and there will be no output current overshoot due to mode crossover.

Remote Operation

To enable all outputs in constant current mode at turn on send: DCPON 2

To disable all outputs in constant c urrent mode at turn-on send: DCPON 3

Table 5-8. Error Messages Front Panel Response

NO ERROR 0 This is the response to the ERR? query when there are no errors. INVALID CHAR 1 You sent the supply a character it did not recognize. INVALID NUM 2 Format of your number is incorrect. Check number syntax. INVALID STR 3 or 28 Occurs when you send a command the supply does not understand. SYNTAX ERROR 4 Either too many parameters are sent without delimiters or the number

NUMBER RANGE 5 An out of range number was sent. Send a new number within the legal range. NO QUERY 6 Computer addressed the supply to talk, but it did not first request data. Send query

DISP LENGTH 7 Quoted string exceeds the display length of 12 characters. Shorten string to a

GP-IB

Code

Explanation

representation is incorrect. Follow the Syntax Diagram in Figure 5-2. Check spaces and delimiters.

first then address supply to talk.

maximum of 12 characters.

BUFFER FULL 8 This error may occur if too many numbers are sent. Error #4 or #5 may occur first. EEPROM ERROR 9 EEPROM is not responding correctly to programming commands. An instrument

failure has occurred and service is required.

HARDWARE ERR 10 An output error has occurred in an unknown output. Service is required.

Remote Operation

Table 5-8. Error Messages (continued) Front Panel Response

HDW ERR CH 1 11 Errors 11 through 14 refer to a specific output where there is an output error.

HDW ERR CH 2 12 Same as in Error #11. HDW ERR CH 3 13 Same as in Error #11. HDW ERR CH 4 14 Same as in Error #11. NO MODEL NUM 15 The interface cannot find its model number. There may be a hardware failure or

CAL ERROR 16 You tried to use either a calibration command with CMODE off or the calibration

UNCALIBRATED 17 There is an incorrect checksum in the EEPROM possibly as a result of incorrect

CAL LOCKED 18 Calibration was attempted with the Calibration Jumper on the GP-IB board in the

GP-IB

Code

Explanation

Service is required.

the instrument may require reprogramming. Service is required.

failed while in CMODE. Enable CMODE and check numbers sent during calibration. Also, there could be a hardware error.

calibration procedure. Recalibrate, and if the problem persists, your supply has a hardware failure.

lockout position. Reposition jumper if desired . See Service Manual.

SKIP SELF TST 22 The self test jumper on the GP-IB board is in the Skip Self Test positio n. No self-

test was done. This is for diagnostics only. See Service Manual.

Table 5-9. TEST Responses

Code Explanation

0 This is the response to the TEST? query when there are no errors.

20 The timer has failed self-test. Refer to the troubleshooting section in the Service Manual.

21 The RAM has failed self-test. Refer to the troubleshooting section in the Service Manual.

27 The ROM has failed the checksum test. Refer to the troubleshooting section in the Service Manual.

29 There is an incorrect checksum in the EEPROM for non-volatile state storage. The non-volatile states 0-3

have not been loaded. Store new values, if problem persists , your supply has a hardware failure.

30 The store limit has been reached for CMODE, store states 0-3, DCPON, or SRQ. The power must be

turned off/on to reenable.

Remote Operation

Local Operation

Introduction

Chapter 3 introduced you to the supply’s front panel controls and indicators to help you turn on the supply and perform the checkout procedures that were given in that chapter. The following paragraphs describe how to use all of the front panel controls and indicators. Most of the remote operations described in Chapter 5 can also be performed locally from the supply’s front panel.

Local Mode

In order to use the front panel keys to control the supply, the local mode must be in effect. The local mode is in effect immediately after power is applied. Table 5-3 lists the initial settings for all of the power supply’s functions when power is initially applied. When the local mode is in effect (RMT annunciator off), the Output Function, System Functio n, and Numeric Entry keys on the front panel (see Figure 6-1) can be used to operate the power supply.

In the remote mode (front panel RMT annunciator on), the front panel keys will have no effect on any of the supply’s outputs and only the computer can con trol the supply. You can, however, still u se the front panel display to view the outp ut voltage and current readings or the present settings for the selected output channel while t he s upply is in the remote mode.

You can return the supply to the local mode from the remote mode by pressing the LCL key provided that the local lockout command has not been received from the GP-IB controller. Pressing the LCL key will also turn the supply’s display back on if it was turned off with a DSP command during remote operation (see page 81). A change between the local and remote modes will not result in a change in the power supply’s outputs.

Local Control Of Output Functions

The Output Function keys (see Figure 6-1) allow you to control the selected output. Figure 6-1 shows the annunciator arrow over OUTPUT 2 indicating that output channel 2 is selected. Pressing the OUTPUT SELECT key selects the output

channels in forward (>) or reverse (<) sequence. Note that Figure 6-1 illustrates the front panel for the Agilent 6626A supply which has four output annunciators. The front panel for Agilent Model 6625 is identical to Figure 6-1 except it has two output annunciators.

General

The power supply will accept programming values directly in volts and amps. The programmable voltage, current, and overvoltage ranges for the outputs of each model are given in Table 5-4. The power supply will round off the values received to the nearest multiple of the resolution for that particular output. If you send a value out of the valid range, it will not be executed and the ERR annunciator will come on. You can get a readout of the error on the display by pressing the ERR key. For an out-of-range error, the error message ’’NUMBER RANGE" will be displayed.

When you press the VSET, ISET, or OVSET key, the output selected and the present setting for that function will be displayed. You can change the setting using the numeric entry keys. Pressing the number keys will cause the present numeric setting to become blank and be replaced with the new numbers on the display. You can use the Ï key to erase previous keystro kes if you ma ke a mista ke.

Local Operation

OUTPUT

ANNUNCIATOR

CHANNEL 1

DISPLAY

LOCAL MODE

KEY

OUTPUT FUNCTION KEYS

6626A SYSTEM DC POWER SUPPLY

VOLTS AMPS

45.153 14.235m

1 2 3 4 CV CC UNR OCP ERR RMT ADDR SRQ

LINE

OFF

ENBLD-- OUTPUT --

LCL

SYSTEM OUTPUT ENTRY

ADDR

ERR

STO

RCL

RANGE V/I

OVSET

OCP

RESET

VOLT

CURR

OUTPUT SELECT

VSET

ISET

OUTPUT

ON/OFF

789

456

123

ENTER

SYSTEM FUNCTION KEYS NUMERIC ENTRY KEYS

Figure 6-1. Front Panel (Model 6626A shown)

Pressing the ENTER key will enter the values displayed for the function indicated, initiate that function, and return the display to the metering mode in which the measured output voltage and current for the selected output are d isplayed. Pressing the ENTER key without entering numbers will result in retention of the previous values and return to the metering mode. You can also return to the metering mode at anytime by pressing the RESET key.

The RANGE V/I key is used to display the voltage and current range settings. The key toggles; pressing it will display the range, pressing it again will put the display back to background metering. The range display shows the largest values of voltage and current that can be set for the ranges presently set.

The voltage step and current step (arrow keys) are used to change voltage & current settings and voltage & current ranges. There are 3 modes:

1. To use the step keys to immediately change the output settings, the background metering mode must be in affect.

2. To use the step keys to change the setting, the VSET or ISET key must be pressed first. The step keys can then be used to

adjust the setting. Press the ENTER key to change the actual setting.

3. To use the step keys to change the voltage or current ranges first press the RANGE V/I key. The step keys change the

range as long as the RANGE display is in effect.

Note The step keys change the voltage or current by 1 LSB each time they are pressed. If the key is held down

more than 1 second, the automatic step mode goes into effect. The step rate will start to increase from the initial value after about 3 seconds.

Setting Voltage and Voltage Range

The selected output’s voltage is programmed locally using the VSET key. For example, program the voltage to 5.25 volts by pressing:

VSET 5 . 2 5 ENTER

The front panel display then indicates the actual o utput voltage and current for the selected output.

Local Operation

The voltage step keys can also be use d to change the voltage setting.

VSET ÑVOLT or ÒVOLT then ENTER

The voltage can be set in the immediate execute mode. This mode is in effect when background

metering is in effect. Pressing ÑVOLT or ÒVOLT will change t he setting

and the effect on the voltage and current can be observed on the display.

The voltage range can be changed by using the RANGE V/I key and the voltage step keys.

RANGE V/I ÑVOLT or ÒVOLT

The range will change as soon as one o f t he vo ltage step keys is pressed and the d isplay will be updated. If the voltage setting is greater then the highest value of t he low range and the range is changed from high to low, the VSET will be automatically reduced to the maximum voltage of the low range.

Setting Current and Current Range

The selected output’s current is programmed locally using the ISET key. For example, program the current to 1.5 amps by pressing:

ISET 1 . 5 ENTER

The power supply will accept any programmed current between zero and the minimum programmable current and automatically set the output to the minimum programmable current without causing a programming error. See Table 5-4.

The current step keys can also be used to change the current setting.

ISET ÑCURR or ÒCURR then ENTER

The current can be set in the immediate execute mode. This mode is in effect when background

metering is in effect. Pressing ÑCURR or ÒCURR will change the setting

and the effect on the voltage and current can be observed on the display.

The current range can be changed by using the RANGE V/I key and the current step keys.

RANGE V/I ÑCURR or ÒCURR

The range will change as soon as one of the current step keys is pressed and the display will be updated. If the current setting is greater then the highest value of t he low range and the range is changed from high to low, the ISET will be automatically reduced to the maximum current of the low range.

Enabling/Disabling an Output

The selected output channel can be turned on and off from the front panel. The OUTPUT ON/OFF key toggles the selected output on and off. When an output is turned off, the message "DISABLED" will be displayed.

The OUTPUT ON/OFF key will not affect any other programmed functions nor will it reset an overvoltage or overcurrent condition. An output disabled by the OUT PUT ON/OFF key will behave as if it were programmed to zero volts and 10 mA.

Local Operation

Setting Overvoltage Protection

Programmable overvoltage protection (OVP) guards your load against overvoltage by crowbarring and downprogramming the power supply output if the programmed overvoltage setting is exceeded.

A fixed OV circuit with a trip level about 20 percent above the maximum programmable voltage acts as a backup to the programmable OVP. When overvoltage protection is activated, the output is shorted and the message ’’OVERVOLTAGE’’ will appear on the front panel display.

The selected output’s overvoltage setting is programmed locally using the OVSET key. For example, program the overvoltage to 10.5 volts by pressing:

OVSET 1 0 . 5 ENTER

Resetting Overvoltage Protection

The condition that caused the OVP must fir st b e cleared and then the output can be returned to its previous state by pressing the RESET key.

Enabling/Disabling Overcurrent Protection

The overcurrent protection feature guards against excessive output currents. When the output goes into the + CC mode and OCP is enabled, the OCP circuit is activated which downprograms the output voltage and disables the output. For this condition, the message ’’OVERCURRENT’’ appears on the front panel display.

The selected output’s overcurrent protection feature can be turned on and off from the front panel. The OCP key toggles the selected output’s overcurrent protection circuit on and off. When it is on (enabled), the OCP ENBLD annunciator will be on.

Resetting Overcurrent Protection

The condition that activated the OCP circuit must first be cleared and then the output can be returned to its previous state by pressing the RESET key.

Local Control Of System Functions

The System Function keys consist of the ADDR, ERR, STO, and RCL keys as shown in Figure 6-1. These keys are independent of the output selected and are used in setting the supply’s GP-IB address, displaying error messages, and storing/recalling voltage and current settings for all of the supply’s output channels.

Setting the Supply’s GP-IB Address

As described in page 40, before you can operate the supply remotely, you must know its GP-IB address. You can find this out locally from the front panel by pressing:

ADDR

The supply’s present address will appear in the display. Address 5 is the factory set address.

If you want to leave the address set at 5, you can return to the metering mode by pressing the METER key or you can press another function key.

If you want to change the address, you can enter a new value.

Any integer from 0 through 30 can be selected.

Local Operation

For example, you can change the address of your supply to 10 by pressing:

ADDR 1 0 ENTER

Displaying Error Messages

The power supply can detect both programming and hardware errors. Upon detecting an error, the ERR annunciator on the front panel comes on and the ERR bit in the serial poll register will be set (see page 78).

When an error is detected, you can display the error message by pressing the ERR key. The power supply will return the error message to the display and clear the error bit. For example, if you program a number that is not within the valid range, the ERR annunciator will come on. You can d isplay the error message by pressing the ERR key. In this case, the error message "NUMBER RANGE" will be displayed. Errors generated either locally from the front panel or remotely from the GP-IB computer can be displayed by pressing the ERR key only when the supply is in the local mode. Pressing the ERR key also clears the error bit so if you press ERR again, the message "NO ERROR" will appear. All error codes and associated display messages are listed in Table 5-8.

Storing and Recalling Voltage and Current Settings for All Outputs

As described on page 75, the power supply has 11 internal registers for storing voltage and current settings of all outputs. At power on each location contains zero volts and the minimum current limit (see initial conditions on page 71).

The STO and RCL keys allow you to stor e and recall voltage and current settings for all your output channels from any of the 11 internal registers (numbered 0 through 10). For example, you can store the present settings of voltage and current for all the output channels in internal register 2 by pressing:

STO 2 ENTER

You can change the settings of any of your supply’s outputs any number of times as required and then program them to the settings stored in internal register 2 by pressing;

RCL 2 ENTER

The internal registers 0-3 will retain the settings when power is turned off. When power is turned off and then on again, registers 4-10 will be reset to zero voltage and the current to 10 mA. Register 0 is the power on state. The power will be programmed from values in register 0 at power on.

The advantages in using the i nternal registers are that command processing time is saved and repetitive programming of different settings is simplified. The STO key can be used in conjunction with the OUTPUT ON/OFF key to store settings while the outputs are disabled (OFF). These stored settings can be used later to program the outputs to the stored setting s using the RCL and OUTPUT ON/OFF keys.

Local Operation

Alignment Procedures

Introduction

This appendix contains the software alignment procedures for the power supply. These supplies should be aligned twice a year, or whenever certain repairs are made (see Service Manual).

The equipment that you need and the test setups to perform the alignment are also shown. A listing of the alignment procedure appears at the end of Appendix A. Refer to Appendix C (Command Summary) for detailed explanations of the commands used within the alignment program.

Because there are no internal or external hardware adjustments, your power supply can be aligned without removing the covers or removing it from the cabinet if it is rack mounted. Alignment is performed by measuring actual output values and sending them to the supply over the GP-IB.

Security against accidental alignment is available. A jumper inside the unit may be moved from NORMAL to CAL LOCKOUT to disable all alignment commands. Access to this jumper requires opening the unit (see Service Manual).

If a number returned to the power supply is out of range while running the alignment program, the front panel ERR annunciator will indicate an error. For example, an error will be created if the DMM is connected to measure a current when a voltage measurement is anticipated by the program.

Note The memory used to store correction constants will accept and store data about 10,000 times, which is

more than sufficient for normal calibrations over the life of the instrument. However, do not put the unit in a calibration loop that repeatedly turns the calibration mode on and off.

Test Equipment and Setup Required

The following test equipment is required for alignment:

1. A computer connected to the GP-IB connector on the back of the power supply.

2. An Agilent 3458A Digital Multimeter (DMM).

3. A precision 0.1 ohm ±0.003%, 5 A shunt resistor (4 terminal). Recommended--Leeds & Northrop Part Number 4221-B

(in oil bath) or Guildline - Part Number 9330/.l/Agilent (in air).

In line 130, change the constant SHUNT_r to the actual measured value of the shunt being used.

Figures A-1 through A-5 show setups required for aligning the power supply. You will be instructed by the program to refer to a particular setup. Observe polarity when connecting the DMM.

Calibration Program

The following alignment program can be used as is, provided you have an HP Series 200/300 computer with the BASIC programming language and an Agilent 3458A DMM. Refer to Appendix C (Command Summary) for further information on the commands used within the program.

Ali g nment Procedures

The program contains embedded comments (identified by a leading asterisk {! } ) which explain various sections and procedures. To reduce keystroking, the program may be shortened to a minimum number of lines by eliminating these comments.

The alignment program is available on a 5¼ floppy (Agilent P/N 06626-10001) or 3½ inch microfloppy (Agilent P/N 06626-10002). Both disks also contain a verification program, which tests the power supply's output programming and readback accuracy to ensure that it is aligned correctly.

The program will automatically recognize what model power supply is being tested, the number of outputs the power supply has, and which type output it is testing. Using this information, the program will calibrate each of the power supply.

After the program has finished calibratin g the power supply, it will store the calibration co nstants and turn off the calibration mode.

Type in the program and press RUN.

The program first does some "house keeping".

It will clear the screen, and assign a number of Common Variables (lines 100 - 130).

The program next assigns the address of the power supply to 705 (line 160) and the address of the DMM to 722 (line 170). It will then assign the CRT as the output device (line 180) and the value of the current shunt. Enter the exact measured value at line 190.

The power supply is sent a CLR command (line 210), which will set it to the turn on state. It will then identify what model power supply is being tested (lines 220 and 230).

Next it will preset the DMM (line 250) and set the DMM sample (line 260).

It will now place the power supply in calibration mode (line 300).

The program is now ready to perform the calibrations on the power supply.

The program will first perform a subprogram (called at line 360 and performed in lines 3420 - 3630) which will set up the output parameters of the output under test.

The program will then calibrate its voltage programming and readback circuitry (the subprogram is called at lines 370 and 380, and performed in lines 1430 - 1920). During this subprogram, the controller will pause, and request that the user set up the power supply and DMM referring to a figure in this Appendix. Press CONTINUE when ready.

Next the overvoltage circuitry will be calibrated (the subprogram is called in line 390, and performed in lines 1960 - 2070).

The current alignment tests on the 2 Amp, 50 W outputs are made using a shunt, be sure that the DMM is connected to the HI and LO voltage input terminals when the shunt is used.

The current circuitry will be calibrated next (the subprograrn is called in lines 400 and 410, and performed in lines 2110 -

2700). During this subprogram, the controller will pause and request that the user set up the power supply and DMM referring to a figure in this Appendix. Press CONTINUE when ready.

Finally the program will calibrate its current sink readback circuitry (performed in lines 2740 - 3380). To perform the current sink readback alignment on the Agilent 6626A, outputs of equivalent current capability are used as pairs. For example outputs 1 and 2 are used to test each other, the outputs 3 and 4 are used to test each other.

In order to perform the current sink readback alignment on the Agilent 6625A, the program automatically limits the current of output 2 (the 50 W output) to 0.5 Amps (line 2780).

Alignment Procedures

After testing of a channel is completed, the pro gram will check if any errors have occurred (the subprogram is called in line 850 and performed in lines 3670 - 3780). If an error has occurred, a message will be sent to the output device (CRT).

After all outputs are tested without errors, the CAL MODE will be turned off, and the calibration constants stored.

Figure A-1

Figure A-2

Figure A-3

Figure A-4

Figure A-1

Figure A-5

Figure A-2

Ali g nment Procedures

Figure A-3

Figure A-4

Alignment Procedures

Figure A-5

Alignment Program

10 ! This program called "ALIGN_6626" will align 20 ! the Agilent6625A, 26, 28 and 29A Power Supplies It 30 ! requires an Agilent3458A DMM and a four terminal 40 ! 0.1 ohm current shunt accurate to +/-50 ppm 50 ! 60 ! May 06,l989 Rev A.03.01 70 ! 80 Clear_screen ! Call program to clear display 90 ! 100 COM /Specs/ Vrng_lo,Vrng_hi,Irng_lo,Irng_hi 110 COM /Ps/ Chan,Other_chan,@Ps,Model$[7] 120 COM /Outputs/ No_of_outputs 130 COM /Vm/ @Vm 140 COM /Shunt/ Shunt_r 150 ! 160 ASSIGN @Ps TO 705 ! Set Supply address to 705 170 ASSIGN @Vm TO 722 ! Set DMM address to 722 180 PRINTER IS 1 ! Print to the CRT 190 Shunt_r= 1 ! Set value of curr ent shunt 200 ! 210 OUTPUT @Ps;"CLR" ! Preset Supply to turn on state 220 OUTPUT @Ps;"ID?" ! Queries Supply model number 230 ENTER @Ps;Model$ ! Enter model number 240 ! 250 OUTPUT @Vm;"PRESET NORM;TRIG HOLD" ! Preset DMM 260 OUTPUT @Vm; “NPLC 100” ! Set DMM sample

270 ! 280 ! 290 ! 300 OUTPUT @Ps;"CMODE 1" ! Turn on Supply CAL mode 310 ! 320 IF Model$="Agilent6625A" OR Model$='Agilent6628A" THEN No_of_outputs=2 330 IF Model$="Agilent6626A" OR Model$="Agilent6629A" THEN No_of_outputs=4 340 ! 350 FOR Chan=1 TO No_of_outputs ! Loop to test all outputs 360 Get_data ! Call program with range data 370 Cal_voltage(Vrng_lo) ! Call program to cal low range voltage 380 Cal_voltage(Vrng_hi) ! Call program to cal high range voltage 390 Cal_overvoltage(Vrng_hi) ! Call program to cal overvoltage 400 Cal_current(Irng_lo) ! Call program to cal low range current 410 Cal_current(Irng hi) ! Call program to cal high range current 420 NEXT Chan ! Test next output 430 ! 440 Chan=l ! Select channel to cal sink (-CC) 450 Other_chan=2 ! Select current source channel 460 Get_data ! Call program with range data 470 Cal_sink(Irng_lo,1) ! Call program to cal low range sink 480 ! 1 is + polarity for DMM 490 Chan=2 ! Select channel to cal sink (-CC) 500 Other_chan=l ! Select current source channel 510 Get_data ! Call program with range data 520 Cal_sink(Irng_lo,-1) ! Call program to cal low range sink

Ali g nment Procedures

Alignment Program (continued)

530 ! -1 is reverse polarity, this saves 540 ! reversing leads as sink channel 550 ! becomes the source for other channel 560 Chan=1 ! Select channel to cal sink (-CC) 570 Other_chan=2 ! Select current source channel 580 Get_data ! Call program with range data 590 Cal_sink(Irng_hi,1) ! Call program to cal high range sink 600 ! 610 Chan=2 ! Select channel to cal sink (-CC) 620 Other_chan=1 ! Select current source channel 630 Get_data ! Call program with range data 640 Cal_sink(Irng_hi,-1) ! Call program to cal high range sink 650 ! 660 IF No_of_outputs=4 THEN ! Cal outputs 3 & 4 670 Chan=3 ! Select channel to cal sink (-CC) 680 Other_chan=4 ! Select current source channel 690 Get_data ! Call program with range data 700 Cal_sink(Irng_lo,1) ! Call program to cal low range sink 710 ! 720 Chan=4 ! Select channel to cal sink (-CC) 730 Other_chan=3 ! Select current source channel 740 Cal_sink(Irng_lo,-1) ! Call program to cal low range sink 750 ! 760 Chan=3 ! Select channel to cal sink (-CC) 770 Other_chan=4 ! Select current source channel 780 Cal_sink(Irng_hi,1) ! Call program to cal high range sink 790 ! 800 Chan=4 ! Select channel to cal sink (-CC) 810 Other_chan=3 ! Select current source channel 820 Cal_sink(Irng_hi,-1) ! Call program to cal high range sink 830 END IF 840 : 850 Check_error ! Call error checking program 860 Cal_mode_off ! Call program to turn cal mode off 870 ! 880 END 890 ! 900 ! 910 ! 920 SUB Clear_screen ! Subprogram to clear display 930 OUTPUT 2;CHR$(255)&CHR$(75); ! Clear screen 940 SUBEND 950 ! 960 ! 970 ! 980 DEF FNDcv ! Function to r at voltage 990 COM /Vm/ @Vm 1000 OUTPUT @Vm;"DCV" ! Set DMM to read DC voltage 1010 TRIGGER @Vm ! Take a voltage reading 1020 ENTER @Vm;Volts ! Enter the voltage 1030 RETURN Volts ! Return voltage reading 1040 FNEND ! End of voltage function

Alignment Procedures

Alignment Program (continued)

1050 ! 1060 ! 1070 ! 1080 DEF FNDci(I_range) ! Function to read current 1090 COM /Vm/ @Vm 1100 COM /Shunt/ Shunt_r 1110 IF I_range=2 THEN ! 2A must read across shunt 1120 Amps=FNDcv/Shunt_r ! Convert shunt voltage to Amps 1130 ELSE! ! <2A read direct from DMM 1140 OUTPUT @Vm;"DCI" ! Set DMM to read DC current 1150 TRIGGER @Vm ! Take a current reading 1160 ENTER @Vm;Amps ! Enter the current 1170 END IF 1180 RETURN Amps ! Return the current reading 1190 FNEND 1200 ! 1210 ! 1220 ! 1230 SUB Output_on ! Subprogram to turn ON outputs 1240 COM /Ps/ Chan,Other_chan, @Ps, Model$[7] 1250 COM /Outputs/ No_of_outputs 1260 OUTPUT @Ps; OUT l,l;OUT 2,1 ! Turn on outputs 1 & 2 1270 IF No_of_outputs=4 THEN OUTPUT @Ps;"OUT 3,1;OUT 4,1" 1280 ! Turn on outputs 3 & 4 1290 SUBEND 1300 ! 1310 ! 1320 ! 1330 SUB Output_off ! Subprogram to turn OFF outputs 1340 COM /Ps / Chan, Other_chan, @Ps, Mode1$ [ 7 ] 1350 COM /Outputs/ No_of_outputs 1360 OUTPUT @Ps;"OUT 1,0,OUT 2,0" ! Turn off outputs 1 & 2 1370 IF No_of_outputs=4 THEN OUTPUT @Ps; “OUT 3,0;OUT 4,0”

1380 ! Turn off outputs 3 & 4 1390 SUBEND 1400 ! 1410 ! 1420 ! 1430 Cal_voltage : SUB Cal_voltage(V_range) ! Subprogram to cal voltage 1440 COM /Ps/ Chan,Other_chan,@Ps,Model$ [7] 1450 ! 1460 IF V_range=50 THEN GOTO Cal_v ! Skip setup instructions 1470 Output_off ! Turn off all outputs 1480 Clear_screen 1490 PRINT "Set up output";Chan;"for voltage calibration 1500 PRINT 1510 PRINT " Use Fig A-1 of the Operating Manual" 1520 PRINT 1530 PRINT “ 3458A input is connected to VOLTAGE terminals” 1540 PRINT 1550 PRINT " The current shunt is NOT used" 1560 PRINT

Ali g nment Procedures

Alignment Program (continued)

1570 PRINT "Press CONTINUE when ready 1580 PAUSE 1590 Output_on 1600 ! 1610 Cal_v: ! 1620 Clear_screen 1630 PRINT "Calibrating the";V _range;"volt range programming”

1640 ! 1650 OUTPUT @Ps;"VRSET" ;Chan,V_range ! Set voltage range 1660 ! 1670 OUTPUT @Ps; VLO";Chan ! Set to low output voltage 1680 WAIT 1 ! Wait for supply to stabilize 1690 Vlo=FNDcv ! Read low voltage 1700 ! 1710 OUTPUT @Ps; “VHI” ;Chan ! Set to high output voltage 1720 WAIT 1 ! Wait for supply to stabilize 1730 Vhi=FNDcv ! Read high voltage 1740 ! 1750 OUTPUT @Ps; “VDATA” ;Chan, Vlo, Vhi ! Send output voltage data 1760 ! 1770 Clear_screen 1780 PRINT "Calibrating the";V_range,'volt range readback" 1790 ! 1800 OUTPUT @Ps; VRLO";Chan ! Set low readback voltage 1810 REPEAT ! Wait for supply to finish 1820 UNTIL BIT(SPOLL(@Ps),4) ! Finished when Bit 4 goes true 1830 Vrlo=FNDcv ! Read low output voltage 1840 ! 1850 OUTPUT @Ps; “VRHI”;Chan ! Set high readback voltage 1860 REPEAT ! Wait for supply to finish 1870 UNTIL BIT(SPOLL(@Ps),4) ! Finished when Bit 4 goes true 1880 Vrhi=FNDcv ! Read high output voltage 1890 ! 1900 OUTPUT @Ps; “VRDAT”; Chan, Vrlo, Vrhi ! Send voltage readback data 1910 ! 1920 SUBEND 1930 ! 1940 ! 1950 ! 1960 Cal_overvoltage:SUB Cal_overvoltage(V_range) ! Sub program to cal OV 1970 COM /Ps/ Chan,Other_chan,@Ps,Model$[7] 1980 ! 1990 Clear_screen 2000 PRINT "Calibrating the Overvoltage circuit 2010 ! 2020 OUTPUT @Ps;"VRSET";Chan,V_range ! Set voltage range 2030 OUTPUT @Ps;"OVCAL";Chan ! Calibrate Overvoltage 2040 REPEAT ! Wait for supply to finish 2050 UNTIL BIT(SPOLL(@Ps),4) ! Finished when Bit 4 goes true 2060 ! 2070 SUBEND 2080 !

Alignment Procedures

Alignment Program (continued)

2090 ! 2100 ! 2110 Cal_current: SUB Cal_current(I_range) ! Subprogram to cal current 2120 COM /Ps/ Chan,Other_chan,@Ps,Model$[7] 2130 ! 2140 IF I_range= .5 THEN GOTO Cal_i ! Skip setup instructions 2150 ! 2160 Output_off 2170 ! 2180 Clear_screen 2190 PRINT "Set up output";Chan;"for";I_range;”A current calibration”

2200 PRINT 2210 IF I_range=2 THEN ! If the next cal range is 2 2220 ! amps then print this message 2230 PRINT " Use Fig A-3 of the Operating Manual" 2240 PRINT 2250 PRINT “3458A input is connected to VOLTAGE terminals” 2260 PRINT 2270 PRINT “The current shunt IS used” 2280 ELSE ! If not 2 amps then print this 2290 PRINT “Use Fig A-2 of the Operating Manual” 2300 PRINT 2310 PRINT “3458A input is connected to CURRENT terminals” 2320 PRINT 2330 PRINT “The current shunt is NOT used” 2340 END IF 2350 PRINT 2360 PRINT “Press CONTINUE when ready” 2370 PAUSE 2380 Output_on 2390 ! 2400 Cal_i : ! 2410 Clear_screen 2420 PRINT "Calibrating the";I_range;"A current programming 2430 ! 2440 OUTPUT @Ps;"IRSET";Chan,I_range ! Set current range 2450 OUTPUT @Ps;''ILO'';Chan ! Set output current low 2460 WAIT 1 ! Wait for supply to stabilize 2470 Ilo=FNDci(I_range) ! Read low output current 2480 ! 2490 OUTPUT @Ps;"IHI";Chan ! Set output current high 2500 WAIT 1 ! Wait for supply to stabilize 2510 Ihi=FNDci(I_range) ! Read high output current 2520 ! 2530 OUTPUT @Ps;”IDATA”;chan,Ilo,Ihi ! Set output current data 2540 ! 2550 Clear_screen 2560 PRINT 'Calibrating the";I_range;"A current readback" 2570 ! 2580 OUTPUT @Ps;"IRLO";Chan ! Set low readback current 2590 REPEAT ! Wait for supply to finish 2600 UNTIL BIT(SPOLL(@Ps),4) ! Finished when Bit 4 goes true

Ali g nment Procedures

Alignment Program (continued)

2610 Irlo=FNDci(I_range) ! Read low output current 2620 ! 2630 OUTPUT @Ps;"IRHI";Chan ! Set high readback current 2640 REPEAT ! Wait for supply to finish 2650 UNTIL BIT(SPOLL(@Ps),4) ! Finished when Bit 4 goes true 2660 Irhi=FNDci(I_range) ! Read high output current 2670 ! 2680 OUTPUT @Ps;"IRDAT";Chan,Irlo,Irhi ! Send current readback data 2690 ! 2700 SUBEND 2710 ! 2720 ! 2730 ! 2740 Cal_sink SUB Cal_sink(I_range,Polarity) ! Subprogram to cal -CC 2750 COM /Ps/ Chan,Other_chan,@Ps,Model$[7] 2760 ! 2770 IF I_range= .5 THEN GOTO Sink_rb ! Skip setup instructions 2780 IF Model$="Agilent6625A" AND I_range=2 THEN I_range= .5 2790 ! If a 6625A, 2A output will be 2800 ! set to 5A to match output 1 2810 IF Chan=2 OR Chan=4 THEN GOTO Sink_rb ! Skip setup instructions 2820 ! 2830 Output_off 2840 Clear_screen 2850 PRINT “Set up output';Cha n;”for ;I_range; “A current SINK cal”

2860 PRINT 2870 PRINT “ Connect outputs”;Chan; “and” ;Other_chan; “together as in” 2880 ! 2890 IF I range=2 THEN ! If it is 2A output use setup 5 2900 PRINT " Fig A-5 of the Operating Manual' 2910 PRINT 2920 PRINT " 3458A input is connected to VOLTAGE terminals" 2930 PRINT 2940 PRINT " The current shunt IS used for this part" 2950 PRINT " of the alignment" 2960 ELSE ! If not 6626A 2A use setup 4 2970 PRINT “Fig A-4 of the Operating Manual” 2980 PRINT 2990 PRINT “3458A input is connected to CURRENT terminals” 3000 PRINT 3010 PRINT " The current shunt IS NOT used" 3020 END IF 3030 PRINT 3040 PRINT “The sink readback of both outputs” 3050 PRINT “will be aligned with this setup” 3060 ! 3070 PRINT 3080 PRINT "Press CONTINUE when ready” 3090 PAUSE 3100 ! 3110 Sink_rb 3120 Clear_screen

100

Alignment Procedures

Agilent Technologies 6626A, 6625A, 6628A, 6629A User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

SAFETY SUMMARY

DECLARATION OF CONFORMITY

WHAT THIS MANUAL CONTAINS

Table Of Contents

General Information

Introduction

Safety Considerations

Instrument and Manual Identification

Options

Accessories

Description

Basic Operation

Specifications

Installation

Introduction

Initial Inspection

Location and Cooling

Input Power Requirements

Line Fuse

Power Cord

Line Voltage Conversion

Getting Started

Introduction

Front Panel Controls and Indicators

Turning On Your Supply

Checking Out Your Supply Using Local Control

Introduction To Remote Operation

Output Connections and Operating Information

Introduction

Output Ranges

Protection Features

Connecting The Load

Remote Voltage Sensing

Overvoltage Trigger Connections

Power Supply Protection Considerations

Parallel Operation

Series Operation

Remote Operation

Introduction

GP-IB Operation

Programming Syntax

Initial Conditions

Power Supply Commands

Local Operation

Introduction

Local Mode

Local Control Of Output Functions

Local Control Of System Functions

Alignment Procedures

Introduction

Test Equipment and Setup Required

Calibration Program

Alignment Program