Agilent Technologies n3302a, n3305a, n3304a, n3306a, n3303a User Manual

...

USER’S GUIDE

Agilent Technologies

DC Electronic Loads

Models N3300A, N3301A, N3302A,

N3303A, N3304A, N3305A and N3306A

Part No. 5964-8196 Printed in Malaysia Microfiche No. 5964-8197 October, 2001

Warranty Information

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 Institute of Standards and Technology, to the extent allowed by the Institute'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 three years from date of delivery. Agilent Technologies software and firmware products, which are designated by Agilent Technologies 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 Technologies does not warrant that the operation for 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 Technologies. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products returned to Agilent Technologies for warranty service. Except for products returned to Customer from another country, Agilent Technologies shall pay for return of products to Customer.

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

If Agilent Technologies 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 Technologies.

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 TECHNOLOGIES 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 TECHNOLOGIES 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 contacts, product maintenance agreements and customer assistance agreements are also available. Contact your nearest Agilent Technologies Sales and Service office for further information on Agilent Technologies' full line of Support Programs.

Safety Summary

ply

The following general safety precautions must be observed during all phases of operation of this instrument. Failure to com

with these precautions or with specific warnings elsewhere in this manual violates safety standards of design,

acture, and intended use of the instrument. Agilent Technologies assumes no liability for the customer's failure to

manu comply with these requirements.

GENERAL

This product is a Safety Class 1 instrument (provided with a protective earth terminal). The protective features of this product may be impaired if it is used in a manner not specified in the operation instructions.

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

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 operating temperature range.

BEFORE APPLYING POWER

Verify that all safety precautions are taken. Note the instrument's external markings described under "Safety Symbols".

GROUND THE INSTRUMENT

This product is a Safety Class 1 instrument (provided with a protective earth terminal). To minimize shock hazard, the instrument chassis and cover must be connected to an electrical ground. The instrument must be connected to the ac power mains through a grounded power cable, with the ground wire firmly connected to an electrical ground (safety ground) at the power outlet. Any interruption of the protective (grounding) conductor or disconnection of the protective earth terminal will cause a potential shock hazard that could result in personal injury.

ATTENTION: Un circuit de terre continu est essentiel en vue du fonctionnement sécuritaire de l'appareil. Ne jamais mettre l'appareil en marche lorsque le conducteur de mise … la terre est d‚branch‚.

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 except as instructed in this Guide for installing or removing electronic load modules. Component replacement and internal adjustments must be made only 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 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 shock hazard. Operation at line voltages or frequencies in excess of those stated on the data plate may cause leakages in excess of 5.0mA peak.

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

SAFETY SYMBOLS

Direct current

Alternating current

Both direct and alternating current

Three-phase alternating current

Earth (ground) terminal

Protective earth (ground) terminal

Frame or chassis terminal

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

Terminal for Neutral conductor on permanently installed equipment

WARNING

Caution

Terminal for Line conductor on permanently installed equipment

On (supply)

Off (supply)

Standby (supply). Units with this symbol are not completely disconnected from ac mains when this 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.

In position of a bi-stable push control

Out position of a bi-stable push control

Caution, risk of electric shock

Caution, hot surface

Caution (refer to accompanying documents)

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 the like, which, if not correctly performed or adhered to, could 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.

Declaration Page

DECLARATION OF CONFORMITY

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

Manufacturer's Name Manufacturer's Address

declares that the Products

Product Names

Model Numbers

Product Options

EMC information:

Conforms with the protection requirements of European Council EMC Directive 89/336/EEC on the approximation of the laws of the member states relating to electromagnetic compatibility:

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

Assessed by: Celestica Ltd, Appointed Competent Body

Agilent Technologies, Inc. 140 Green Pond Road Rockaway, New Jersey 07866 U.S.A.

a) dc Electronic Load Mainframes b) dc Electronic Load Modules for Mainframe

a) N3300A, N3301A b) N3302A, N3303A, N3304A, N3305A and N3306A

This declaration covers all options and customized products based on the above as stated in TCF Certificate of Conformance CC/TCF/00/084

CC/TCF/00/084 based on Technical Construction File (TCF) ANJ10, dated Sept. 26, 2000

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

Safety information:

The product herewith complies with the requirements of the Low Voltage Directive 73/23/EEC and carries the CE-marking accordingly.

Supplementary Information:

The product conforms to the following safety standards:

IEC 1010-1:1990+A1+A2 / EN 61010-1:1993 +A2 UL 3111-1:1994 CSA C22.2 No. 1010.1:1993

January, 2001 Date Hank Kowalla / Quality Manager

European contact for regulatory topics only Your local Agilent Technologies Sales and Service Office or

Agilent Technologies GmbH, HQ-TRE, Herrenberger Straße 130, D-71034 Böblingen (FAX: +49-7031-14-3143)

Acoustic Noise Information

Herstellerbescheinigung

Diese Information steht im Zusammenhang mit den Anforderungen der Maschinenlä minformationsverordnung 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).

Printing History

The edition and current revision of this manual are indicated below. Reprints of this manual containing minor corrections and updates may have the same printing date. Revised editions are identified by a new printing date. A revised edition incorporates all new or corrected material since the previous printing date.

Changes to the manual occurring between revisions are covered by change sheets shipped with the manual. In some cases, the manual change applies only to specific instruments. Instructions provided on the change sheet will indicate if a particular change applies only to certain instruments.

This document contains proprietary information protected by copyright. All rights are reserved. No part of this document may be photocopied, reproduced, or translated into another language without the prior consent of Agilent Technologies. The information contained in this document is subject to change without notice.

Update 1 ________ November 2000 Update 2 ________ June 2001

Warranty Information ...........................................................................................................................................................2

Safety Summary...................................................................................................................................................................... 3

Declaration Page ..................................................................................................................................................................... 5

Acoustic Noise Information....................................................................................................................................................6

Printing History ......................................................................................................................................................................6

Table of Contents....................................................................................................................................................................7

QUICK REFERENCE ............................................................................................................ 11

The Front Panel -At a Glance..............................................................................................................................................11

The Rear Panel At a Glance.................................................................................................................................................12

Instrument Configuration....................................................................................................................................................12

Front Panel Number Entry..................................................................................................................................................13

Front Panel Annunciators.................................................................................................................................................... 14

Immediate Action Keys ........................................................................................................................................................14

Front Panel Menus - At a Glance ........................................................................................................................................ 15

SCPI Programming Commands - At a Glance ..................................................................................................................17

GENERAL INFORMATION................................................................................................... 19

Document Orientation.......................................................................................................................................................... 19

Safety Considerations...........................................................................................................................................................20

Options and Accessories....................................................................................................................................................... 20

Description ............................................................................................................................................................................20

Features and Capabilities....................................................................................................................................................21

Front Panel Controls...........................................................................................................................................................21

Remote Programming.........................................................................................................................................................21

Operating Modes ..................................................................................................................................................................22

Constant Current CC (Mode) ............................................................................................................................................. 22

Constant Resistance (CR) Mode ........................................................................................................................................23

Constant Voltage (CV) Mode.............................................................................................................................................24

Transient Operation ............................................................................................................................................................. 26

List Operation....................................................................................................................................................................... 27

Triggered Operation............................................................................................................................................................. 27

Input Control ........................................................................................................................................................................30

Protection Features............................................................................................................................................................... 30

Saving and Recalling Settings.............................................................................................................................................. 33

External Control Signals...................................................................................................................................................... 33

Remote Sensing.................................................................................................................................................................. 33

Monitor Outputs ................................................................................................................................................................. 33

External Programming Input..............................................................................................................................................33

Fault....................................................................................................................................................................................34

Port On/Off......................................................................................................................................................................... 34

Input Measurements............................................................................................................................................................. 34

DC Measurements .............................................................................................................................................................. 35

RMS Measurements ...........................................................................................................................................................35

Minimum and Maximum Measurements ...........................................................................................................................35

Power Measurements .........................................................................................................................................................35

Measurement Ranges .........................................................................................................................................................35

INSTALLATION.....................................................................................................................37

Inspection ..............................................................................................................................................................................37

Damage ..............................................................................................................................................................................37

Packaging Material............................................................................................................................................................. 37

Items Supplied.................................................................................................................................................................... 37

Cleaning .............................................................................................................................................................................37

Installing the Modules ..........................................................................................................................................................38

Procedure............................................................................................................................................................................38

Channel Number ................................................................................................................................................................39

Location ................................................................................................................................................................................. 40

Bench Operation................................................................................................................................................................. 41

Rack Mounting...................................................................................................................................................................41

Input Connections................................................................................................................................................................. 42

Power Cord......................................................................................................................................................................... 42

Manually-Tightened Connectors........................................................................................................................................42

8mm Screw Terminal Connector (option UJ1) ..................................................................................................................43

Wire Considerations...........................................................................................................................................................44

Control Connector.............................................................................................................................................................. 46

Sense Switch ......................................................................................................................................................................47

Trigger and Digital Connections ........................................................................................................................................ 47

Computer Connections......................................................................................................................................................... 48

GPIB Interface....................................................................................................................................................................48

RS-232 Interface ................................................................................................................................................................48

Application Connections ......................................................................................................................................................49

Local Sense Connections....................................................................................................................................................49

Remote Sense Connections ................................................................................................................................................49

Parallel Connections........................................................................................................................................................... 49

Low Voltage Operation...................................................................................................................................................... 51

TURN-ON CHECKOUT ......................................................................................................... 53

Introduction ..........................................................................................................................................................................53

Checkout Procedure .............................................................................................................................................................53

In Case of Trouble ................................................................................................................................................................54

Error Messages................................................................................................................................................................... 54

Selftest Errors.....................................................................................................................................................................54

FRONT PANEL OPERATION ............................................................................................... 55

Introduction ..........................................................................................................................................................................55

Front Panel Description ....................................................................................................................................................... 55

System Keys...........................................................................................................................................................................57

Function keys ........................................................................................................................................................................ 58

Immediate Action Keys...................................................................................................................................................... 58

Scrolling Keys.................................................................................................................................................................... 59

Metering Keys.................................................................................................................................................................... 59

Input Control Keys............................................................................................................................................................. 60

Transient Control Keys ......................................................................................................................................................61

Trigger Control Keys..........................................................................................................................................................61

List Control Keys ...............................................................................................................................................................61

Entry Keys............................................................................................................................................................................. 62

Examples of Front Panel Programming .............................................................................................................................63

1 - Using the Front Panel Display ......................................................................................................................................63

2 - Programming Constant Current, Voltage and Resistance Modes .................................................................................63

3 - Programming Transient Operation................................................................................................................................65

4 - Programming Lists........................................................................................................................................................ 67

5 - Querying and Clearing Output Protection and Errors ................................................................................................... 68

6 - Making Basic Front Panel Measurements.....................................................................................................................69

7 - Setting the GPIB Address .............................................................................................................................................70

8 - Storing and Recalling Instrument States....................................................................................................................... 70

SPECIFICATIONS................................................................................................................. 71

PERFORMANCE TEST AND CALIBRATION PROCEDURES ............................................ 75

Introduction ..........................................................................................................................................................................75

Equipment Required ............................................................................................................................................................75

Performance Tests ................................................................................................................................................................76

IMON Zero Verification ....................................................................................................................................................76

CC Mode Tests................................................................................................................................................................... 76

CV Mode Tests...................................................................................................................................................................77

CR Mode Tests................................................................................................................................................................... 79

Transient Generator Mode Tests ........................................................................................................................................ 81

Agilent N3302A Verification Test Record.........................................................................................................................83

Agilent N3303A Verification Test Record.........................................................................................................................84

Agilent N3304A Verification Test Record.........................................................................................................................85

Agilent N3305A Verification Test Record.........................................................................................................................86

Agilent N3306A Verification Test Record.........................................................................................................................87

Calibration ............................................................................................................................................................................90

Parameters Calibrated.........................................................................................................................................................90

IMON, IPROG and CURRENT Calibration Program .......................................................................................................91

VOLTAGE Calibration Program .......................................................................................................................................95

RESISTANCE Calibration Program .................................................................................................................................. 97

INDEX.................................................................................................................................. 101

Manual Updates................................................................................................................................................................105

Quick Reference

The Front Panel -At a Glance

j15-character display shows

channel, voltage and current measurements.

N3300A

SYSTEM DC ELECTRONIC LOAD

CHANNEL VOLTS AMPS

CV CC CR Unr Dis Tran Prot Cal Shift Rmt Addr Err SQR

LINE

k Annunciators indicate

operating modes and status conditions.

SYSTEM FUNCTION ENTRY

Sense

Ident

Meter

Local

Error

Channel

Address

Channel

Save

Prot Clear Protect

Recall

Input on/off

Func

Current

Res

Voltage

l System keys:

♦ Return to Local mode. ♦ Set the GPIB address. ♦ Set the RS-232 interface. ♦ Display SCPI error codes. ♦ Save and recall instrument

states.

Step

List Tran

Trigger

Trigger Control

E -

Clear Entry

Input

Enter

OFF

m Function keys:

♦ Select metering functions. ♦ Enable/disable input. ♦ Program current, resistance and

voltage modes.

♦ Set and clear protection

functions.

♦ Scroll through front panel

menu commands.

n Entry keys:

♦ Enter values. ♦ Increment or decrement values.

o Turns the electronic load on

and off.

1 - Quick Reference

The Rear Panel At a Glance

Q Control connector R Input binding post S GPIB connector T RS-232 interface

connector

1 2 3

U Power cord

connector

V Trigger/Digital

connector

W Sense switch

Instrument Configuration

Use the front panel Address menu to

♦ Select GPIB or RS-232 interface (see Chapter 5 in User's Guide).

♦ Select the GPIB bus address (see Chapter 5 in User's Guide).

♦ Configure the RS-232 interface (see Chapter 5 in User's Guide).

Front Panel Number Entry

Enter numbers from the front panel as follows:

Use the Entry Scroll keys to adjust the input setting in Meter mode.

Quick Reference - 1

Meter

AND



Input



Input

If CC is lit, the input current changes.

If CV is lit, the input voltage changes.

If CR is lit, the input resistance changes.

NOTE The input must be on for input values to change.

Use the Function keys and Entry keys to enter a new value

NOTE If you make a mistake use the Backspace key to delete the number, or press the Meter key to

return to the Meter mode.

Current

Res

AND AND

Voltage

789

E -

Clear Entry

Input

Enter

1 - Quick Reference

Front Panel Annunciators

φφφφ1

A list is initiated or running.

Prot

Indicates that a channel protection feature is active

on any channel. Press the Prot Clear key to clear the protection condition.

The selected input channel is in the

constant voltage (CV) mode.

The selected input channel is in the

Cal

Shift

Calibration mode is ON. Calibration can only be

done through the computer interface.

Indicates that the shift key has been pressed.

constant current (CC) mode.

The selected input channel is in the

constant resistance (CR) mode.

Rmt

Indicates that the electronic load is in remote state

(either GPIB or RS-232). In the remote state, only the active key is the Local key.

Unr

Dis

The selected input channel is unregulated.

The input is OFF. Press the Input on/off

Addr

Err

The electronic load is addressed to talk or listen.

A remote programming error(s) have occurred.

key to turn the input on.

Tran

The selected input channel is enabled for

SQR

The electronic load is requesting a service.

transient operation.

Immediate Action Keys

Input

On/Off

Local

A toggle switch that turns the input of the electronic load on or off.

Activates front panel control when the unit is in remote mode

(unless a Lockout command is in effect).

QQQQ

Input



Input

QQQQ

Channel

Shift

Trigger

Increases the input current (CC), voltage (CV), or resistance (CR) in Meter mode.

Decreases the input current (CC), voltage (CV), or resistance (CR) in Meter mode.

Selects another channel.

Causes an initiate and trigger to occur. Used with transient subsystem or list.

Displays any protection functions that are tripped.

Protect

Shift

Prot

Clear

Ident

IdentShift

Resets the protection circuit and allows the unit to return to its last programmed state.

Identifies the module installed in the selected channel location. (not available)

Meter

Returns the front panel to metering mode from any other mode.

Front Panel Menus - At a Glance

Quick Reference - 1

Address

Recall

Shift Shift

Func

Protect

Meter

Current

Res

RRRR RRRR

RRRR

SaveShift

Erro

Channel

SenseShift

RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR

ADDRESS 5 INTF GPIB BAUDRATE 300 PARITY NONE FLOW NONE *RCL 0 *RST

*SAV 0 ERROR 0 CHANNEL 1 S:PNT S:TIN S:WIN S:OFF S:C:RNG S:V:RNG FUNC FNC:MODE INP:SHOR

OC -- -- -RRV --- --

XXXX XXXX XXXX V MAX XXXX V MIN XXXX V RMS XXXX A MAX XXXX A MIN XXXX A RMS XXXX WATTS XXXX W MAX XXXX W MIN CURR C:MODE C:RANG C:SLEW C:SLW:N C:SLW:P C:TLEV C:TRIG RES R:MODE R:RANG R:SLEW R:SLW:N R:SLW:P R:TLEV R:TRIG

Sets the GPIB Address Selects an interface (GPIB or RS232) Selects baud rate (300, 600, 1200, 2400, 4800, 9600) * Selects message parity (NONE, EVEN, ODD, MARK, SPACE) * Selects flow control (XON-XOFF, RTS-CTS, DTR-DSR, NONE) * Recalls the instrument state Resets the instrument to its power-on state

Saves the present instrument state Displays the number of errors in the SCPI error queue Allows selection of channel to be controlled by the front panel Defines the number of data points in the measurement Sets the digitizer sample spacing Sets the measurement window function (RECT, HANN) Defines the data offset in the measurement Selects the current measurement range Selects the voltage measurement range Sets the regulation mode (CURR, RES, VOLT) Selects what controls regulating mode (FIX, LIST) Enable/disables the input short (OFF/ON)

General protection status (overcurrent fault shown) Voltage protection status (remote reverse voltage fault shown)

Displays the input voltage and current Displays the maximum voltage Displays the minimum voltage Displays the rms voltage Displays the maximum current Displays the minimum current Displays the rms current Displays the wattage Displays the maximum wattage Displays the minimum wattage Sets the input current Sets the current mode (FIXED, LIST) Sets the input current range Sets current slew rate Sets current slew rate for negative transitions Sets current slew rate for positive transitions Sets the transient input current Sets the triggered input current Sets the input resistance Sets the resistance mode (FIXED, LIST) Sets the input resistance range Sets resistance slew rate Sets resistance slew rate for negative transitions Sets resistance slew rate for positive transitions Sets the transient input resistance Sets the triggered input resistance

*Only applicable for use with RS-232

1 - Quick Reference

Front Panel Menus - continued

Voltage

Tran

Trigge

List

VOLT

RRRR

RRRR RRRR

RRRR

RRRR RRRR

V:MODE V:RANG V:SLEW V:SLW:N V:SLW:P V:TLEV V:TRIG TRAN

RRRR

RRRR RRRR RRRR

T:DCYC T:FREQ T:MODE T:TWID

INIT:IMMED

RRRR

ABORT LST:STEP

RRRR RRRR RRRR

RRRR

RRRR RRRR

RRRR RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR

RRRR RRRR

RRRR RRRR RRRR

LST:CNT DWEL:0 EOL CURR:0 EOL C:RANG:0 EOL C:SLEW:0 EOL C:SLW:N:0 EOL C:SLW:P:0 EOL C:TLEV:0 EOL FUNC:0 EOL RES:0 EOL R:RANG:0 EOL R:SLEW:0 EOL R:SLW:N:0 EOL R:SLW:P:0 EOL R:TLEV:0 EOL TRAN:0 EOL T:DCYC:0 EOL T:FREQ:0 EOL T:MODE:0 EOL T:TWID:0 EOL VOLT:0 EOL V:RANG:0 EOL V:SLEW:0 EOL V:SLW:N:0 EOL V:SLW:P:0 EOL V:TLEV:0 EOL

Sets the input voltage Sets the voltage mode (FIXED, LIST) Sets the input voltage range Sets voltage slew rate Sets voltage slew rate for negative transitions Sets voltage slew rate for positive transitions Sets the transient input voltage Sets the triggered input voltage Enables/disables the transient generator (OFF/ON) Sets the transient duty cycle in continuous mode Sets the transient frequency in continuous mode Sets the transient mode (CONT, PULSE, TOGGLE) Sets the transient pulse width in pulse mode

Initiates the trigger system Aborts the initiated trigger Sets the method of incrementing steps (ONCE, AUTO)

Specifies the number of times the list is cycled Specifies the time period of each step Specifies the current setting for each step Specifies the current range for each step Sets the current slew rate for each step Sets the negative current slew rate for each step Sets the positive current slew rate for each step Sets the transient input current for each step Sets the list regulation mode (CURR, RES, VOLT) Specifies the resistance setting for each step Specifies the resistance range for each step Sets the resistance slew rate for each step Sets the negative resistance slew rate for each step Sets the positive resistance slew rate for each step Sets the transient input resistance for each step Enables/disables the transient level for each step Sets the transient duty cycle for each step Sets the transient frequency for each step Sets the mode of the transient generator (CONT, PULSE) Sets the transient pulse width for each step Specifies the voltage setting for each step Specifies the voltage range for each step Sets the voltage slew rate for each step Sets the negative voltage slew rate for each step Sets the positive voltage slew rate for each step Sets the transient input voltage for each step

Quick Reference - 1

SCPI Programming Commands - At a Glance

NOTE Most [optional] commands have been omitted for clarity. Refer to the Programming Guide for

a complete description of all programming commands.

ABORt CALibrate :DATA <n> [,<n>] :IMON:LEVel <points> :IPRog:LEVel <points> :LEVel <points> :PASSword <n> :SAVE :STATE <bool> [,<n>] CHANnel | INSTrument [:LOAD] <n> INITiate [:IMMediate] :SEQuence[1] | :SEQuence2 :NAMe LIST | ACQuire CONTinuous :SEQuence1 <bool> :NAMe LIST <bool> INPut | OUTput [:STATe] <bool> :PROTection :CLEar :SHORt [:STATe] <bool> MEASure | FETCh :ARRay :CURRent? :POWer? :VOLTage? [:SCALar] :CURRent? :ACDC? :MAX? :MIN? :POWer? :MAX? :MIN? :VOLTage? :ACDC? :MAX? :MIN? PORT0[:STATe] <bool> PORT1[:LEVel] <n> SENSe :CURRent :RANGe <n> :SWEep :OFFSet :POINts <n> :TINTerval <n> :WINDow <type> :VOLTage :RANGe <n>

[SOURce:] CURRent [:LEVel] <n> :TRIG <n> :MODE <mode> :PROTection [:LEVel] <n> :DELay <n> :STATe <bool> :RANGe <n> :SLEW [:BOTH] <n> :NEGative <n> :POSitive <n> :TLEVel <n> FUNCtion | MODE :MODE <mode> LIST :COUNt <n> :CURRent [:LEVel] <n> {,<n>} :POINts? :RANGe <n> {,<n>} :POINts? :SLEW [:BOTH] <n> {,<n>} :POINts? :NEGative <n> {,<n>} : POSitive <n> {,<n>} :TLEVel <n> {,<n>} :POINts? :DWELI <n> {,<n>} :POINts? :FUNCtion | MODE <mode> :RESistance [:LEVel] <n> {,<n>} :POINts? :RANGe <n> {,<n>} :POINts? :SLEW [:BOTH] <n> {,<n>} :POINts? :NEGative <n> {,<n>} : POSitive <n> {,<n>} :TLEVel <n> {,<n>} :POINts? :STEP <step> :TRANsient [:STATe] <bool> {,<bool>} :POINts? :DCYCle <n> {,<n>} :POINts? :FREQuency <n> {,<n>} :POINts? :MODE <mode> {<mode>} :POINts? :TWIDth <n> {,<n>} :POINts?

1 - Quick Reference

SCPI Commands - continued

[SOURce:]LIST (continued)

:VOLTage [:LEVel] <n> {,<n>} :POINts? :RANGe <n> {,<n>} :POINts? :SLEW [:BOTH] <n> {,<n>} :POINts? :NEGative <n> {,<n>} : POSitive <n> {,<n>} :TLEVel <n> {,<n>} :POINts? RESistance [:LEVel] <n> :TRIG <n> :MODE <mode> :RANGe <n> :SLEW [:BOTH] <n> :NEGative <n> :POSitive <n> :TLEVel <n> TRANsient [:STATe] <bool> :DCYCle <n> :FREQuency <n> :MODE <mode> :TWIDth <n> VOLTage [:LEVel] <n> :TRIG <n> :MODE <mode> :RANGe <n> :SLEW [:BOTH] <n> :NEGative <n> : POSitive <n> :TLEVel <n>

STATus

:CHANnel [:EVENt]? :CONDition? :ENABle <n> :CSUMmary [:EVENt]? :ENABle <n> :OPERation [:EVENt]? :CONDition? :ENABle <n> :NTRansition <n> :PTRansition <n> :QUEStionable [:EVENt]? :CONDition? :ENABle <n> SYSTem :ERRor? :VERSion? :LOCal :REMote :RWLock TRIGger [:IMMediate] :DELay :SOURce <source> :TIMer :SEQuence2 | ACQuire :COUNt

General Information

Document Orientation

This manual describes the operation of the Agilent Model N3300A, N3301A, N3302A, N3303A N3304A, N3305A and N3306A DC Electronic Loads. Unless otherwise noted, all units will be referred to by the description "electronic load" throughout this manual. The following documents and software are shipped with your electronic load:

♦ A User's Guide (this document), contains installation, checkout and front panel information.

♦ A Programming Guide, contains detailed GPIB programming information.

The following Getting Started Map will help you find the information you need to complete the specific task that you want to accomplish. Refer to the table of contents or index of each guide for a complete list of the information contained within.

Getting Started Map

Task Where to find information

Installing the unit

Line voltage connections Installing modules Load connections

Checking out the unit

Verifying proper operation Using the front panel Calibrating the unit

Using the front panel

Front panel keys Front panel examples

Using the programming interface

GPIB interface RS-232 interface

Programming the unit using SCPI commands

SCPI commands SCPI programming examples

Programming the unit using VXIplug&play instrument driver

Installing the instrument driver Instrument driver functions C/C++ example programs Visual BASIC example programs Lab VIEW example programs Agilent VEE example programs

User's Guide

User's Guide Programming Guide

Programming Guide

VXIplug&play on-line help NOTE: The driver must be installed on your computer to access the on-line information. Drivers for Agilent instruments are available on the web at www.agilent.com/find/drivers

2 - General Information

Safety Considerations

This electronic load is a Safety Class 1 instrument, which means it has a protective earth terminal. That terminal must be connected to earth ground through power source equipped with a ground receptacle. Refer to the Safety Summary page at the beginning of this guide for general safety information. Before installation or operation, check the electronic load and review this guide for safety warnings and instructions. Safety warnings for specific procedures are located at appropriate places in the Guide.

Options and Accessories

Table 2-1 Options

Option Description

800 One rack mount kit for two N3301A half-rack units side by side*.

Consists of: Lock-link kit (p/n 5061-9694) and Flange kit (p/n 5062-9215)

908 One rack mount kit*.

Consists of: Flange kit for N3300A (order 2 p/n 5063-9212)

Flange kit for N3301A (p/n 5062-3960)

909 One rack mount kit with handles for N3300A* (order 2 p/n 5063-9219).

UJ1 8mm input screw terminal connectors (see chapters 2 and 3)

*Support rails (p/n E3663AC) are required.

Table 2-2 Accessories

GPIB cables

1.0 meter (3.3 ft)

2.0 meters (6.6 ft)

4.0 meters (13.2 ft)

0.5 meters (1.6 ft)

RS-232 cable

(9-pin F to 9-pin F, 2.5 meter, null modem/printer cable with one 9-pin M to 25 pin F adapter)

RS-232 adapter kit (contains 4 adapters)

9-pin M to 25-pin M for pc or printer 9-pin M to 25-pin M for pc or printer 9-pin M to 25-pin M for modem 9-pin M to 9-pin M for modem

Agilent Part Number

10833A 10833B 10833C 10833D 34398A

34399A

Description

The N3300A is a DC Electronic Load Mainframe used for design, manufacturing, and evaluation of dc power supplies, batteries, and power components. Other applications include use as a power circuit breaker or crowbar, high current function or pulse generator, fuel-cell and photovoltaic cell test, and de-energizing superconducting magnets.

The mainframe contains six slots for load modules. Load modules occupy either 1 or 2 slots depending on the power rating of the module. The mainframe can dissipate up to 300 watts per slot, to a total of 1800 watts for a fully loaded mainframe. Each individual module has its own channel number and contains its own input connector. The mainframe contains a processor, GPIB connector, RS-232 connector and interface circuits, trigger circuits, front-panel keypad and display, and other circuits common to all the load modules.

General Information - 2

The N3301A is a DC Electronic Load Mainframe that is functionally identical to the N3300A, but is a half-rack width with only two slots for load modules. The mainframe can dissipate up to 300 watts per slot, to a total of 600 watts for a fully loaded mainframe.

The N3302A, N3303A N3304A, N3305A and N3306A are electronic load modules that can be installed in the N3300A and N3301A mainframes. The module specific pages in Appendix A include specifications and other information pertinent to a particular model. Each module can operate independently in constant current (CC) mode, constant voltage (CV) mode, or constant resistance (CR) mode. In addition, each input can be turned on or off (open-circuited), or short-circuited.

Features and Capabilities

♦ Constant current (CC), constant voltage (CV), or constant resistance (CR) mode operation.

♦ Built-in GPIB and RS-232 interface programming with SCPI command language.

♦ Triggered input and measurement functions.

♦ Front panel control with keypad.

♦ Independent channel operation.

♦ Built-in pulse generator for continuous, pulsed, and toggled transient operation.

♦ Overvoltage, overcurrent, overpower, and overtemperature protection.

♦ Extensive selftest, status reporting and software calibration.

♦ Fan speed control for reduced acoustic noise under light load conditions.

Front Panel Controls

The front panel has keyboard controls for setting the input voltage, current and resistance. The panel display provides digital readouts of a number of functions including the inputs. Annunciators display the operating status of the electronic load. System keys let you perform system functions such as setting the GPIB address and recalling operating states. Front panel function keys access the electronic load function menus. Front panel Entry keys let you select and enter parameter values. Refer to chapter 5 for a complete description of the front panel controls.

Remote Programming

The electronic load may be remotely programmed via the GPIB bus and/or an RS-232 serial port. GPIB programming is done with SCPI (Standard Commands for Programmable Instruments) commands, which make the electronic load programs compatible with those of other GPIB instruments that are also SCPI compatible.

Local (front panel) control is in effect immediately after power is applied. The front panel keypad and display allow manual control of each individual module when the electronic load is used in bench test applications. Remote (computer) control goes into effect (front panel Rmt annunciator is on) as soon as the mainframe receives a command via the GPIB. A built-in GPIB interface and SCPI commands allow control and readback of all functions when the electronic load is used in computer controlled applications.

With remote control in effect, only the computer can control the electronic load; the front panel keypad has no effect. You can still use the front panel display to view the input voltage and current readings. To return the electronic load to local control, press the Local key. This will return the electronic load to local control, unless the local-lockout command has been received from the GPIB controller.

Most functions that can be performed remotely over the GPIB or RS-232 can also be performed from the front panel. Whenever possible the function menu commands reflect their corresponding SCPI commands. Thus, learning to operate the electronic load from the front panel will aid you when writing computer programs.

2 - General Information

Operating Modes

The three modes of operation are:

♦ Constant current (CC).

♦ Constant voltage (CV).

♦ Constant resistance (CR).

When programmed to a mode, a module remains in that mode until the mode is changed or until a fault condition, such as an overpower or overtemperature, occurs.

The current, resistance, and voltage mode parameters described in subsequent paragraphs can be programmed whether or not the mode is presently selected. When a mode is selected via the front panel or via the GPIB or RS-232, most of the associated parameters will take effect at the input (exceptions are noted in the mode descriptions).

Constant Current CC (Mode)

In this mode, the module will sink a current in accordance with the programmed value regardless of the input voltage (see Figure 2-1). The CC mode can be set with front panel keys or via the GPIB or RS-232. The CC mode parameters are discussed in the following paragraphs.

Figure 2-1. Constant Current Mode

Ranges

Current may be programmed in either of two overlapping ranges, a Low range and a High range. The low range provides better resolution at low current settings. The range can be set at the front panel or via the GPIB (CURR:RANG command). When you program a current value, the electronic load automatically selects the range that corresponds to the value that you program. If the value falls in a region where ranges overlap, the electronic load selects the Low range. If the present input setting is outside the Low range, the electronic load will automatically adjust the input setting to the highest value available in the Low range. If you subsequently program an input value that is outside the Low range, an OUT OF RANGE message will appear on the front panel display.

Immediate Current Level

The current level can be set at the front panel or via the GPIB (CURR command). If the CC mode is the active mode, the new setting immediately changes the input at a rate determined by the slew setting (described below). If the module is not in the CC mode, the new setting is saved for use when the mode is changed to CC.

General Information - 2

Triggered Current Level

A current level can be preset (stored in the electronic load) allowing the input to be updated when a trigger is received instead of immediately as described above.

If the CC mode is the active mode, the preset current level will become the actual value and the input will be updated when a trigger occurs. If the CC mode is not the active mode, the preset current level will become the actual value when a trigger occurs but there will be no effect on the input until the CC mode becomes active. Once a level is triggered, subsequent triggers will have no effect on the input unless another CURR:TRIG command is sent. The trigger sources available to the electronic load are described later in this chapter. The electronic load has a status reporting capability to keep track of pending triggers and other operating conditions. The status reporting capability is described in detail in the Programming Guide.

Transient Current Level

The transient current level can be set at the front panel or via the GPIB. The transient current level can be higher or lower than the main current level. The module input will switch between the main level and the transient level when transient operation is turned on.

Software Current Limit

The electronic load allows the user to set a current limit (0 to 102% of full scale) for each module via the GPIB (CURR:PROT command) which will shut down the input if the current limit is exceeded beyond a programmable time delay. Note that the software current limit is in effect for any mode of operation (not just the CC mode). The software current limit feature is described later in this chapter under Protection Features.

Slew Rate

The current slew rate determines the rate at which the input current to a module changes to a new programmed value. Current slew rates are programmed in amperes per second. Slew rates can be set at the front panel or via the GPIB (CURR:SLEW command). The programmed slew rate remains in effect for the immediate, triggered, and transient level changes previously described.

Any slew rate can be programmed provided that it falls between the fastest and the slowest slew rates shown in Figure 2-8A. If a value is programmed that is outside these limits, the module will automatically adjust the programmed value to either the fastest or the slowest slew rates shown in the figure.

Constant Resistance (CR) Mode

In this mode, the module will sink a current linearly proportional to the input voltage in accordance with the programmed resistance (see Figure 2-2). The CR mode can be set at the front panel or via the GPIB (MODE:RES command). The CR mode parameters are described in the following paragraphs.

Ranges

Resistance may be programmed in any of four overlapping ranges. The range can be set at the front panel or via the GPIB (RES:RANG command). When you program a resistance value, the electronic load automatically selects the range that corresponds to the value that you program. If the value falls in a region where ranges overlap, the electronic load selects the range with the highest resolution. If the present input setting is outside the range that you select, the electronic load will automatically adjust the input setting to the closest available value within the newly selected range. If you subsequently program an input value that is outside the newly selected range, an OUT OF RANGE message will appear on the front panel display.

2 - General Information

Figure 2-2. Constant Resistance Mode

Immediate Resistance Level

The resistance level can be set at the front panel or via the GPIB (RES command). If the CR mode is active, the new setting immediately changes the input at a rate determined by the voltage or current slew setting (see description below). If the module is not in the CR mode, the new setting is saved for use when the mode is changed to CR.

Triggered Resistance Level

A resistance level can be preset (stored in the electronic load) allowing the input to be updated when a trigger is received instead of immediately as described above.

If the CR mode is active, the preset resistance level will become the actual value and the input will be updated when a trigger occurs. If the CR mode is not the active mode, the preset resistance level will become the actual value when a trigger occurs but there will be no effect on the input until the CR mode becomes active. Once a level is triggered, subsequent triggers will have no effect on the input unless another RES:TRIG command is sent.

Transient Resistance Level

The transient resistance level can be set at the front panel or via the GPIB (RES:TLEV command). The transient level and the main level are used in transient operation, which is described later in this chapter.

Slew Rate

The resistance slew rate determines the rate at which the input resistance to a module changes to a new programmed value. Resistance slew rates are programmed in ohms per second. Slew rates can be set at the front panel or via the GPIB (RES:SLEW command). The programmed slew rate remains in effect for the immediate, triggered, and transient level changes previously described.

Constant Voltage (CV) Mode

In this mode, the module will attempt to sink enough current to control the source voltage to the programmed value (see Figure 2-3). The module acts as a shunt voltage regulator when operating in the CV mode. The CV mode can be set at the front panel or via the GPIB (MODE:VOLT command). The CV mode parameters are described in the following paragraphs.

Ranges

Voltage may be programmed in either of two overlapping ranges, a low range and a high range. The low range provides better resolution at low voltage settings. The range can be set at the front panel or via the GPIB

General Information - 2

(VOLT:RANG command). When you program a voltage value, the electronic load automatically selects the range that corresponds to the value that you program. If the value falls in a region where ranges overlap, the electronic load selects the Low range. If the present input setting is outside the Low range, the electronic load will automatically adjust the input setting to the highest value available in the Low range. If you subsequently program an input value that is outside the Low range, an OUT OF RANGE message will appear on the front panel display.

Figure 2-3. Constant Voltage Mode

Immediate Voltage Level

The voltage level can be set at the front panel or via the GPIB (VOLT command). If the CV mode is active, the new setting immediately changes the input at a rate determined by the voltage slew setting. If the module is not in the CV mode, the new setting is saved for use when the mode is changed to CV.

Triggered Voltage Level

The voltage level can be preset (stored in the electronic load) allowing the input to be updated when a trigger is received instead of immediately as described above.

If the CV mode is the active mode, the preset current level will become the actual value and the input will be updated when a trigger occurs. If the CV mode is not the active mode, the preset current level will become the actual value when a trigger occurs, but there will be no effect on the input until the CV mode becomes active. Once a level is triggered, subsequent triggers will have no effect on the input unless another VOLT:TRIG command is sent.

Transient Voltage Level

The transient voltage level can be set at the front panel or via the GPIB (VOLT:TLEV command). The module input will switch between the main level and the transient level when transient operation is turned on. The transient voltage level determines the higher voltage level.

Slew Rate

The voltage slew rate determines the rate at which the input voltage to a module changes to a new programmed value. Voltage slew rates are programmed in volts per second. Slew rates can be set at the front panel or via the GPIB (VOLT:SLEW command). The programmed slew rate remains in effect for the immediate, triggered, and transient level changes previously described.

Any slew rate can be programmed provided that it falls between the fastest and the slowest slew rates shown in Figure 2-8B. If a value is programmed that is outside these limits, the module will automatically adjust the programmed value to either the fastest or the slowest slew rates shown in the figure.

2 - General Information

Transient Operation

Transient operation enables the module to periodically switch between two load levels, as might be required for testing power supplies. A power supply's regulation and transient characteristics can be evaluated by monitoring the supply's output voltage under varying combinations of load levels, frequency, duty cycle, and slew rate. Transient operation can be turned on and off at the front panel or via the GPIB (TRAN ON and TRAN OFF commands). Before you turn on transient operation, you should set the desired mode of operation as well as all of the parameters associated with transient operation. Transient operation may be used in the CC, CR, or CV modes and can be continuous, pulsed, or toggled.

Continuous

Pulse

Toggled

Continuous Transient Operation

In continuous operation, a repetitive pulse train switches between two load levels. In the front panel, the transient commands are located under the TRAN key. Continuous transient operation is selected via the GPIB using the TRAN:MODE CONT command.

The two load levels in the transient operation are the previously described main level (immediate or triggered) and transient level for current, resistance, or voltage. The rate at which the level changes is determined by the slew rate (see slew rate descriptions for CV, CR, or CV mode as applicable). In addition, the frequency and duty cycle of the continuous pulse train are programmable. The frequency can be set from 0.25 to 10000 Hz at the front panel or via the GPIB (TRAN:FREQ command). The duty cycle can be set from 3% to 97% (0.25 Hz to 1 kHz) or from 6% to 94% (above 1 kHz) at the front panel or via the GPIB (TRAN:DCYC command).

Pulsed Transient Operation

Pulsed transient operation is similar to continuous operation with the following exceptions:

Generates a repetitive pulse stream the toggles between two load levels.

Generates a load change that returns to its original state after some time period.

Generates a repetitive pulse stream that toggles between two load levels. Similar to Continuous mode except that the transient points are controlled by explicit triggers instead of an internal transient generator.

a. In order to get a pulse, an explicit trigger is required. The trigger can be an external trigger signal

received via the TRIGGER input on the rear panel, the TRIG:SOUR function, the *TRG or TRIG commands, the ac line, the internal timer signal, or the front panel Trigger key.

b. One pulse results from each trigger. Therefore, frequency cannot be programmed. The main level,

transient level, and slew rate are programmed as described for continuous operation. The pulse width is programmable from 0.00005 to 4 seconds via the GPIB (TRAN:TWID command).

Toggled Transient Operation

Toggled transient operation causes the module input to alternate between two pre-defined levels as in continuous operation except that the transient points are controlled by explicit triggers instead of the internal transient generator. As in pulsed transient operation, the trigger signal can be an external trigger signal, the GPIB GET function, the *TRG command, the TRIG command, or the ac line or internal timer signals.

General Information - 2

List Operation

List mode lets you generate complex sequences of input changes with rapid, precise timing, which may be synchronized with internal or external signals. This is useful when running test sequences with a minimum amount of programming overhead.

You can program up to 50 settings (or steps) in the list, the time interval (dwell) that each setting is maintained, the number of times that the list will be executed, and how the settings change in response to triggers. All listed data is stored in a non-volatile memory when the *SAV command is executed. This means that the programmed data for any list will be retained when the electronic load is turned off. Note that lists data can only be saved in nonvolatile memory locations 0, 7, 8, or 9. List data will not be saved in other memory locations. Use the *RCL command to recall the saved state.

List steps can be either individually triggered, or paced by a separate list of dwell times which define the duration of each step. Therefore, each of the up to 50 steps has an associated dwell time, which specifies the time (in seconds) that the input remains at that step before moving on to the next step. See chapter 5 for detailed information about programming lists from the front panel.

Triggered Operation

The electronic load has various triggering modes to allow synchronization with other test equipment or events. The triggering circuits are located in the mainframe, and all modules receive the trigger simultaneously (although each module is programmed individually as to what operation, if any, will be triggered. As described previously, triggering can be used for the following applications:

Triggering a preset level

Triggering a transient pulse

Toggling

Triggers can be sent from the front panel by pressing the Trigger key. However you must first initiate the trigger function by executing the TRIG:IMMED command located in the Trigger Control menu.

Three triggering methods are available over the GPIB: the GET function, the *TRG common SCPI command, and the TRIG subsystem SCPI command (refer to Programming Guide). The SCPI TRIG subsystem allows you to select either the ac line frequency, internal timer, or TRIG command as the trigger source. There is also a TRIGGER connector on the rear panel for external trigger inputs.

Transfers all pending preset levels to the actual level. For the presently active mode, the new level appears at the input. For the modes which are not presently active, the preset levels will not take effect at the input until the applicable mode becomes active.

Generates a transient pulse of programmable width when pulsed transient operation is in effect.

Changes the input between the main level and the transient level when toggled transient operation is in effect.

*TRG and the TRIG command are both synchronous with other commands; that is, the modules are not triggered until pending operations are completed. GET, external triggers, ac-line triggers, and internal-timer triggers are all asynchronous; that is, the modules are triggered as soon as the trigger signal is received.

2 - General Information

If the ac line is selected via the GPIB as the trigger source, triggers will be generated once for each cycle of ac input power. An ac line frequency of 60 Hz produces a trigger period of 16.67 ms; 50 Hz line frequency produces a trigger period of 20 ms.

The rear-panel TRIGGER connector also provides a trigger output signal. This signal is generated synchronously with the trigger signal sent by the mainframe to the modules. The trigger output signal can be used to trigger an external device such as an oscilloscope, DVM, or another electronic load mainframe.

The electronic load has a status reporting capability to keep track of trigger operations. Refer to 'Status Reporting' in the Programming Guide.

Slew Rate and Minimum Transition Time

Slew rate is defined as the change in current, resistance, or voltage over time. A programmable slew rate allows a controlled transition from one load setting to another to minimize induced voltage drops on inductive power wiring, or to control induced transients on a test device (such as would occur during power supply transient response testing).

In cases where the transition from one setting to another is large, the actual transition time can be calculated by dividing the voltage or current transition by the slew rate. The actual transition time is defined as the time required for the input to change from 10% to 90% or from 90% to 10% of the programmed excursion. In cases where the transition from one setting to another is small, the small signal bandwidth of the load limits the minimum transition time for all programmable slew rates. Because of this limitation, the actual transition time is longer than the expected time based on the slew rate, as shown in Figure 2-7.

Voltage, Current, or Resistance

Change

100%

90%

10%

Slew Rate

Time

Expected Time

Actual Time

Figure 2-7. Risetime Transition Limitation

General Information - 2

Therefore, both minimum transition time and slew rate must be considered when determining the actual transition time. This is shown in Figure 2-8, which shows the minimum transition time for a given slew rate as a horizontal line, and at about a 13.3% or greater load change, the slew rate increases from the minimum transition time to the Maximum transition time at a 100% load change. The actual transition time will be either the minimum transition time, or the total slew time (transition divided by slew rate), whichever is longer.

Use the following formula to calculate the minimum transition time (MinTT) for a given slew rate:

MinTT (in seconds) =

__________8__________

slew rate (in amps/second)

Use the following formula to calculate the maximum transition time (MaxTT) for a given slew rate:

MaxTT (in seconds) =

__________60__________

slew rate (in amps/second)

NOTE: In voltage mode, all minimum transition times are based on a low-capacitance current source.

These transition times are affected by capacitive loading of the inputs. For example, a capacitance of 2.2 microfarads increases the 85 microsecond minimum transition time (shown in the table) to 110 microseconds.

Minimum

Transition

Time

8000µs

Maximum

60000

lew Rate

est

6000

e A

Rat

lew

Minimum

Transition

Time

8000µs

lew Rate

est

e A

Rat

lew

Maximum

60000

6000

∆

∆ ∆

Time

800µs

Time

800µs

600

Slew Rate B

120µs

astest

13.3% 16.7%

∆

Voltage (% of full scale)

∆ ∆

50% 100%

∆

600

Slew Rate B

e C

Rat

lew

13.3% 16.7%

∆

Current (% of full scale)

∆ ∆

50% 100%

∆ ∆

Figure 2-8. Transition Time Slew Rate Examples

2 - General Information

Input Control

Short On/Off

A module can simulate a short circuit at its input by turning the load on with full-scale current. The short circuit can be toggled on/off at the front panel using the SHORT command in the Func menu, or via the GPIB (INPUT:SHORT ON|OFF command). The short on/off change uses the slew rate setting of the active mode and range.

The actual value of the electronic short is dependent on the mode and range that are active when the short is turned on. In CV mode it is equivalent to programming zero volts. In CC mode it is equivalent to programming full-scale current for the present current range. In CR mode it is equivalent to programming the minimum resistance for the present resistance range.

Note that turning the short on in CV mode may cause the load to draw so much current that the software current limit operates, which may turn the input off.

Turning the short circuit on does not affect the programmed settings, and the load input will return to the previously programmed values when the short is turned off.

Input On/Off

A module's input can be toggled on/off at the front panel, or via the GPIB (INPUT ON|OFF command). The input on/off change does not use the slew rate setting so the input will change at the maximum slew rate.

Turning the input off (zero current) does not affect the programmed settings. The input will return to the previously programmed values when the input is turned on again. Note that the Input On/Off command supersedes the mode commands and Short On/Off command.

Protection Features

Each load module includes the following protection features:

• Overvoltage.

• Overcurrent (hardware and software).

• Overpower.

• Overtemperature.

• Reverse Voltage.

The appropriate bit(s) in the mainframe's status registers are set when any of the above protection features are active. Also, the Prot annunciator comes on and the front-panel alphanumeric display indicates which condition(s) have been detected. For example, if an overtemperature (OT) condition has been detected causing a module's input to be turned off (protection shutdown, PS), the display will indicate "PS OT".

Resetting Latched Protection

All of the protection features latch (remain set) when they are tripped, except for the hardware overcurrent and reverse voltage. The latched protection features can be reset via the GPIB (*RST or INP:PROT:CLE commands) or at the front panel. Of course, the condition that caused the protection feature to trip must be removed or it will trip again as soon as it is reset.

General Information - 2

Caution To protect the electronic load from possible damage, the input voltage must not exceed the

maximum input voltage rating specified in the module-specific pages supplied with each module. Never apply the ac line voltage to a module's input connectors.

Overvoltage

The overvoltage protection circuit is set at a predetermined voltage level, which cannot be changed. If the overvoltage circuit has tripped, the module will attempt to limit the voltage level by drawing current from the dc source. The module limits the value of current drawn such that the resulting power is within the power rating. The overvoltage (OV) and voltage fault (VF) status register bits are set when the OV condition occurs, and will remain set until they are reset as previously described.

An overvoltage condition does not cause the module's input to be turned off. However, a Fault signal (pin A6) output at the module's rear-panel control connector will indicate when either an overvoltage condition or a reverse voltage condition has occurred. The Fault signal is latched true (high TTL level) when the VF bit in the status register goes true. The Fault output signal can be used to trip an external circuit breaker or control a relay in order to disconnect the electronic load input from the source it is testing when an overvoltage or a reverse voltage condition occurs.

Overcurrent

The electronic load includes both hardware and software overcurrent protection features.

Hardware. When operating in the CR or CV mode, it is possible for a module to attempt to sink more current than it is rated for. Under this condition, the load current will be limited by a current limit circuit, which is set at a value slightly above the current rating of the module. It protects both the electronic load and the device under test from operating too far beyond specified limits. The hardware current limit circuit does not turn the module's input off. The overcurrent (OC) bit in the status register is set when an OC condition occurs, and is reset when the OC condition is removed.

Software. In addition to the hardware overcurrent protection circuit, the electronic load allows the user to define a current protection limit in software which will shut down a module's input if the limit is exceeded. This feature can only be programmed via the GPIB. It is turned on/off using the CURR:PROT:STATE ON|OFF command. The software current limit level (in amps) is set using the CURR:PROT command. A programmable delay (in seconds) before trip is also provided with the CURR:PROT:DEL command. If the software overcurrent limit is exceeded and persists beyond the specified delay time, the module is turned off. Also, for these conditions, the OC and PS (protection shutdown) status register bits are set and will remain set until the OC condition is removed and the bits are reset as previously described.

Overpower

The power-limit boundary is set by software that monitors the input current and voltage. If the input power exceeds the power limit, the load module sets the overpower status bit, which will reset if the overpower condition ceases. If the overpower condition persists for 3 seconds, the load module's input circuit turns off, and the OP and PS status bits are both latched on. The input circuit remains off, and the OP and PS status bits remain set, until protection clear occurs. Of course, if the overpower condition is not corrected, the load will turn off again.

Overtemperature

Each module has an overtemperature (OT) protection circuit, which will turn off the input if the internal temperature exceeds safe limits. If the OT circuit activates, the OT and PS status register bits are set and will

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