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Service Guide

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The Agilent Technologies E3631A is a high performance 80 watt-triple output DC power supply with GPIB and RS-232 interfaces. The combination of benchtop and system features in this power supply provides versatile solutions for your design and test requirements.

Convenient bench-top features

• Triple output

• Easy-to-use knob control for voltage and current settings

• Highly visible vacuum-fluorescent display for voltage and current meters

• Tracking operation for ±25V outputs

• Excellent load and line regulation and low ripple and noise

• Operating states storage

• Portable, ruggedized case with non-skid feet

Flexible system features

• GPIB (IEEE-488) and RS-232 interfaces are standard

• SCPI (Standard Commands for Programmable Instruments) compatibility

• I/O setup easily done from front-panel

Agilent E3631A Triple Output DC Power Supply

The Front Panel at a Glance

1 Meter and adjust selection keys 2 Tracking enable/disable key 3 Display limit key 4 Recall operating state key 5 Store operating state/Local key 6 Error/Calibrate key

7 I/O Configuration / Secure key 8 Output On/Off key 9 Control knob 10 Resolution selection keys 11 Voltage/current adjust selection key

1 Meter and adjust selection keys Select the output voltage and current of any one

supply (+6V, +25V, or -25V output) to be monitored on the display and allow knob adjustment of that supply.

2 Tracking enable / disable key Enables / disables the track mode of

±25V supplies.

3 Display limit key Shows the voltage and current limit values on the display and allows

knob adjustment for setting limit values.

4 Recall operating state key Re calls a prev iously stor ed ope r atin g stat e from locati on

"1", "2", or "3".

5 Store operating state / Local key

Stores an operating state in location "1", "2", or

"3" / or returns the power supply to local mode from remote interface mode.

6 Error / Calibrate key

Displays error codes generated during operations, self-test and calibration / or enables calibration mode (the power supply must be unsecured before performing calibration).

7 I/O Configuration / Secure key

Configures the power supply for remote interfaces

/ or secure and unsecure the power supply for calibration.

8 Output On/Off key Enables or disables all three power supply outputs. This key

toggles between two states.

9 Control knob Increases or decreases the value of the blinking digit by turning

clockwise or counter clockwise.

10 Resolution selection keys Move the flashing digit to the right or left.

11 Voltage/current adjust selection key Selects the knob function to voltage control

or current control.

The key can be used as the "Local" key when the power supply is in the remote

interface mode.

You can enable the "calibration mode" by holding down this key when you turn on

the power supply.

You can use it as the "Secure" or "Unsecure" key when the power supply is in the

calibration mode.

Front-Panel Voltage and Current Settings

You can set the voltage and current from the front panel using the following method.

Use the voltage/current adjust selection key, the resolution selection keys, and the control knob to change the limiting or limitings value of voltage or current.

1 Press the key after turning on the power supply.

2 Set the knob to the voltage control mode or current control mode using the voltage/

current adjust selection key.

3 Move the blinking digit to the appropriate position using the resolution selection keys.

4 Change the blinking digit to the desired value using the control knob.

5 Press the key to enable the output. After about 5 seconds, the

display will go to the output monitor mode automatically to display the voltage and current at the output.

Display Limit

Output On/Off

Note All front panel keys and controls can be disabled with remote interface commands.

The Agilent E3631A must be in "Local" mode for the front panel keys and controls to function.

Display Annunciators

Adrs Power supply is addressed to listen or talk over a remote interface. Rmt Power supply is in remote interface mode. +6V Displays the output voltage and current for +6V supply. Knob is active for

+6V supply.

+25V Displays the output voltage and current for +25V supply. Knob is active for

-25V Displays the output voltage and current for -25V supply. Knob is active for

CAL power supply is in calibration mode. Track The outputs of +25V and -25V supplies are in track mode. Limit The display shows the voltage and current limit value of a selected supply. ERROR Hardware or remote interface command errors are detected and also the

OFF The three ouputs of the power supply are disabled. Unreg The displayed output is unregulated (output is neither CV nor CC). CV The displayed output is in constant-voltage mode. CC The displayed output is in constant-current mode.

+25V supply.

-25V supply.

error bit has not been.

To review the display annunciators, hold down key as you

Display Limit

turn on the power supply.

The Rear Panel at a Glance

1 Power-line voltage setting 2 Power-line fuse-holder assembly 3 AC inlet

Use the front-panel key to:

• Select the GPIB or RS-232 interface (see chapter 3).

• Set the GPIB bus address (see chapter 3).

• Set the RS-232 baud rate and parity (see chapter 3).

I/O Config

4 Power-line module 5 GPIB (IEEE-488) interface connector 6 RS-232 interface connector

In This Book

Specifications Chapter 1 lists the power supply’s specifications and describes how to interpret these specifications.

Quick Start

familiar with the front-panel features.

Calibration Procedures Chapter 3 provides performance verification and calibration procedures.

Theory of Operation Chapter 4 describes block and circuit level theory related to the operation of the power supply.

Service Chapter 5 provides guidelines for returning your power supply to Agilent Technologies for servicing, or for servicing it yourself.

Replaceable Parts Chapter 6 contains a detailed parts list of the power supply.

Backdating Chapter 7 describes the difference between this manual and older issues of this manual.

Chapter 2 prepares the power supply for use and helps you get

Schematics Chapter 8 contains the power supply's schematics, disassembly drawings, and component locator drawings.

If you have questions relating to the operation of the power supply, call 1-800-452-4844 in the United States, or contact your nearest Agilent Technologies Sales Office.

Chapter 1 Specifications

Performance Specifications - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15 Supplemental Characteristics - - - - - - - - - - - - - - - - - - - - - - - - - - - 17

Chapter 2 Quick Start

To prepare the power supply for use - - - - - - - - - - - - - - - - - - - - - - 23 To check the rated voltages of the power supply - - - - - - - - - - - - 25 To check the rated currents of the power supply - - - - - - - - - - - - 27 To use the power supply in constant voltage mode - - - - - - - - - - 29 To use the power supply in constant current mode - - - - - - - - - - 31 To use the power supply in track mode- - - - - - - - - - - - - - - - - - - - 33 To store and recall the instrument state - - - - - - - - - - - - - - - - - - - 34 To rack mount the power supply - - - - - - - - - - - - - - - - - - - - - - - - - 36

Chapter 3 Calibration Procedures

Agilent Technologies Calibration Services - - - - - - - - - - - - - - - - - 41 Calibration Interval- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 41 Automating Calibration Procedures - - - - - - - - - - - - - - - - - - - - - - 42 Recommended Test Equipment - - - - - - - - - - - - - - - - - - - - - - - - - - 42 Test Considerations - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 43 Performance Verification Tests - - - - - - - - - - - - - - - - - - - - - - - - - - 44

Self-Test - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 44 Performance Verification Tests- - - - - - - - - - - - - - - - - - - - - - - - - 44

Measurement Techniques- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45

Setup for Most Tests - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45 Electronic Load - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 46 Current-Monitoring Resistor - - - - - - - - - - - - - - - - - - - - - - - - - - - 46 Programming - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 46 Voltage and Current Values - - - - - - - - - - - - - - - - - - - - - - - - - - - - 46

Constant Voltage (CV) Verifications - - - - - - - - - - - - - - - - - - - - - - 47

Constant Voltage Test Setup - - - - - - - - - - - - - - - - - - - - - - - - - - - 47 Voltage Programming and Readback Accuracy - - - - - - - - - - - - 47 CV Load Regulation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49 CV Line Regulation- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 50 Normal Mode Voltage Noise (CV Ripple and Noise) - - - - - - - - 51 Common Mode Current Noise- - - - - - - - - - - - - - - - - - - - - - - - - - 52 Load Transient Response Time - - - - - - - - - - - - - - - - - - - - - - - - - 53

Contents

Chapter 3 Calibration Procedures (continued)

Constant Current (CC) Verifications - - - - - - - - - - - - - - - - - - - - - - 54

Constant Current Test Setup - - - - - - - - - - - - - - - - - - - - - - - - - - - 54 Current Programming and Readback Accuracy - - - - - - - - - - - - 54 CC Load Regulation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 56 CC Line Regulation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 57 Normal Mode Current Noise (CC Ripple and Noise) - - - - - - - - 58

Performance Test Record for Agilent E3631A - - - - - - - - - - - - - - - 59

CV Performance Test Record- - - - - - - - - - - - - - - - - - - - - - - - - - - 59 CC Performance Test Record- - - - - - - - - - - - - - - - - - - - - - - - - - - 60

Calibration Security Code - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 61

To Unsecure the Power Supply for Calibration - - - - - - - - - - - - 62

To Unsecure the Power Supply Without the Security Code - - - 64 Calibration Count - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 65 Calibration Message - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 65 General Calibration/Adjustment Procedure - - - - - - - - - - - - - - - - - 66 Aborting a Calibration in Progress - - - - - - - - - - - - - - - - - - - - - - - - 71 Calibration Record for Agilent E3631A - - - - - - - - - - - - - - - - - - - - 72 Error Messages - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 73 Calibration Program - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 75

Chapter 4 Theory of Operation

Block Diagram Overview - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 81 AC Input and Bias Supplies - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 83 Floating Logic - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 84 D-to-A Converter - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 86 A-to-D Converter - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 87 Power Mesh and Control- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 88 Earth-Referenced Logic - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 90 Front Panel - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 90

Chapter 5 Service

Operating Checklist - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 93

Is the Power Supply Inoperative? - - - - - - - - - - - - - - - - - - - - - - - 93

Does the Power Supply Fail Self-Test? - - - - - - - - - - - - - - - - - - - 93 Types of Service Available - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 94

Standard Repair Service (worldwide) - - - - - - - - - - - - - - - - - - - - 94

Express Exchange (U.S.A. only) - - - - - - - - - - - - - - - - - - - - - - - - 94

Contents

Chapter 5 Service (continued)

Repacking for Shipment - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 95 Electrostatic Discharge (ESD) Precautions - - - - - - - - - - - - - - - - 96 Surface Mount Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 96 To Replace the Power-Line Fuse - - - - - - - - - - - - - - - - - - - - - - - - - 96 Troubleshooting Hints - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 97

Unit is Inoperative - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 97 Unit Reports Errors 740 to 748 - - - - - - - - - - - - - - - - - - - - - - - - - 97 Unit Fails Self-Test - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 97 Bias Supplies Problems - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 98

Self-Test Procedures- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 99

Power-On Self-Test - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 99 Complete Self-Test - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 99

Chapter 6 Replaceable Parts

Replaceable Parts - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 104

To Order Replaceable Parts- - - - - - - - - - - - - - - - - - - - - - - - - - - 104 Backdating and Parts Changes - - - - - - - - - - - - - - - - - - - - - - - - 104 E3631-60002 Top PCB Assembly - - - - - - - - - - - - - - - - - - - - - - - 105 E3631-60003 VFD Assembly- - - - - - - - - - - - - - - - - - - - - - - - - - - 111 E3631-60002 Bottom PCB Assembly - - - - - - - - - - - - - - - - - - - - 112 E3631-60002 Front Frame Assembly - - - - - - - - - - - - - - - - - - - - 116 E3631A Power Supply Assembly - - - - - - - - - - - - - - - - - - - - - - - 116 Manufacturer’s List - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 117

Chapter 7 Backdating - - - - - - - - - - - - - - - - - - - - - - - - - 119

Chapter 8 Schematics

Mechanical Disassembly - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 123 E3631-60002 Component Locator - - - - - - - - - - - - - - - - - - - - - - - 124 E3631-60003 Component Locator - - - - - - - - - - - - - - - - - - - - - - - 125 E3631-60004 Component Locator - - - - - - - - - - - - - - - - - - - - - - - 126 AC Input and Bias Supplies Schematic - - - - - - - - - - - - - - - - - - - 127 Floating Logic Schematic - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 128 ADC and DAC Schematic - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 129 25V Power Circuit Schematic- - - - - - - - - - - - - - - - - - - - - - - - - - - 130 +6V Power Circuit and Isolation Schematic - - - - - - - - - - - - - - - 131 Earth-Referenced Logic Schematic - - - - - - - - - - - - - - - - - - - - - - 132 Display and Keyboard Schematic - - - - - - - - - - - - - - - - - - - - - - - 133

Contents

Specifications

The

performance

are warranted in the temperature range of 0 to 40°C with a resistive load.

Supplemental

performance determined either by design or testing. Chapter 3 "Calibration Procedures" contains procedures for verifying the performance specifications. All specifications apply to the three outputs unless otherwise specified.

specifications are listed in the following pages. Specifications

characteristics, which are not warranted but are descriptions of

Chapter 1 Specifications

Performance Specifications

Output Ratings (@ 0°C - 40°C) +6V Output 0 to +6 V ; 0 to 5 A

+25V Output 0 to +25 V ; 0 to 1 A

-25V Output 0 to -25 V ; 0 to 1 A

[1]

Programming Accuracy

+6V Output

Voltage 0.1% + 5 mV 0.05% + 20 mV 0.05% + 20 mV Current 0.2% + 10 mA 0.15% + 4 mA 0.15% + 4 mA

12 months (@ 25°C ± 5°C), ±(% of output + offset)

+25V Output -25V Output

Readback Accuracy

to actual output @ 25°C ± 5°C), ±(% of output + offset)

Voltage 0.1% + 5 mV 0.05% + 10 mV 0.05% + 10 mV Current 0.2% + 10 mA 0.15% + 4 mA 0.15% + 4 mA

Ripple and Noise (with outputs ungrounded, or with either output terminal grounded, 20 Hz to 20 MHz)

Voltage <0.35 mV rms <0.35 mV rms <0.35 mV rms

Current <2 mA rms <500 mA rms <500 mA rms Common mode current <1.5 mA rms

Load Regulation, Change in output voltage or current for any load change within ratings Voltage <0.01% + 2 mV

Current <0.01% + 250 mA

Line Regulation, Change in output voltage and current for any line change within ratings Voltage <0.01% + 2 mV

Current <0.01% + 250 mA

[1]

12 months (over GPIB and RS-232 or front panel with respect

+6V Output

<2 mV p-p <2 mV p-p <2 mV p-p

+25V Output -25V Output

±(% of output + offset)

[1]

Accuracy specifications are after an 1-hour warm-up and calibration at 25°C

Chapter 1 Specifications

Performance Specifications

Programming Resolution

+6V Output

Voltage 0.5 mV 1.5 mV 1.5 mV Current 0.5 mA 0.1 mA 0.1 mA

Readback Resolution

+6V Output

Voltage 0.5 mV 1.5 mV 1.5 mV Current 0.5 mA 0.1 mA 0.1 mA

Meter Resolution

+6V Output

Voltage 1 mV 10 mV 10 mV Current 1 mA 1 mA 1 mA

Transient Response Time

Less than 50 msec for output recover to within 15 mV following a change in output current from full load to half load or vice versa

+25V Output -25V Output

Command Processing Time

Programming Commands : Maximum time for output to change after receipt of APPLy and SOURce commands : <50 msec

Readback Command : Maximum time to readback output by MEASure? command : <100 msec

The Other Commands : < 50 msec

Tracking Accuracy

±25V outputs track each other within ± (0.2% of output + 20 mV).

The

Chapter 1

Specifications

Supplemental Characteristics

Output Programming Range (maximum programmable values)

+6V Output +25V Output -25V Output

Voltage 0 to 6.18 V 0 to 25.75 V 0 to -25.75 V Current 0 to 5.15 A 0 to 1.03 A 0 to 1.03 A

Temperature Coefficient, ±(% of output + offset) Maximum change in output/readback per °C after a 30-minute warm-up

+6V Output +25V Output -25V Output

Voltage 0.01% + 2 mV 0.01% + 3 mV 0.01% + 3 mV Current 0.02% + 3 mA 0.02% + 0.5 mA 0.02% + 0.5 mA

Stability, ±(% of output + offset) Following a 30-minute warm-up, change in output over 8 hours under constant load,

line, and ambient temperature

+6V Output +25V Output -25V Output

Voltage 0.03% + 1 mV 0.02% + 2 mV 0.02% + 2 mV Current 0.1% + 3 mA 0.05% + 1 mA 0.05% + 1 mA

Voltage Programming Speed

Maximum time required for output voltage to settle within 1% of its total excursion (for resistive load). Excludes command processing time.

+6V Output +25V Output -25V Output

Full load Up 11 msec 50 msec 50 msec Full load Down 13 msec 45 msec 45 msec

No load Up 10 msec 20 msec 20 msec No load Down 200 msec 400 msec 400 msec

Isolation

The 0-6V supply is isolated from the ±25V supply up to ±240 Vdc. Maximum isolation voltage from any terminal to chassis ground ±240 Vdc.

AC Input Ratings (selectable via rear panel selector) std 115 Vac ± 10%, 47 to 63 Hz

opt 0E3 230 Vac ± 10%, 47 to 63 Hz opt 0E9 100 Vac ± 10%, 47 to 63 Hz

Maximum Input Power

350 VA with full load

Chapter 1 Specifications

Supplemental Characteristics

Cooling

Fan cooled

Operating Temperature

0 to 40°C for full rated output. At higher temperatures, the output current is derated linearly to 50% at 55°C maximum temperature.

Output Voltage Overshoot

During turn-on or turn-off of ac power, output plus overshoot will not exceed 1 V if the output control is set to less than 1 V. If the output control is set to 1 V or higher, there is no overshoot.

Programming Language

SCPI (Standard Commands for Programmable Instruments)

State Storage Memory

Three (3) user-configurable stored states

Recommended Calibration Interval

1 year

Dimensions

212.6 mmW x 132.6 mmH x 348.2 mmD (8.4 x 5.2 x 13.7 in)

*See the next page for detailed information.

Weight

Net 8.2 kg (18 lb) Shipping 11 kg (24 lb)

Chapter 1 Specifications

Supplemental Characteristics

Figure 1-1. Dimensions of Agilent E3631A Power Supply

Chapter 1 Specifications

Supplemental Characteristics

Quick Start

One of the first things you will want to do with your power supply is to become acquainted with its front panel. Written procedures in this chapter prepare the power supply for use and familiarize you with most front-panel operations.

• The power supply is shipped from the factory configured in the front-panel

operation mode. At power-on, the power supply is automatically set to operate in the front-panel operation mode. When in this mode, the frontpanel keys can be used. When the power supply is in remote operation mode, you can return to front-panel operation mode at any time by pressing the

Local

key if you did not previously send the front-panel lockout command. A change between front-panel and remote operation modes will not result in a change in the output parameters.

• When you press the key (the Lmt annunciator blinks), the

display of the power supply goes to the limit mode and the present limit values of the selected supply will be displayed. In this mode, you can also observe the change of the limit values when adjusting the knob. If you press

Display Limit

the key again or let the display time-out after several seconds, the power supply will return the display to the meter mode (the Lmt annunciator turns off). In this mode, the actual output voltage and current will be displayed.

• All outputs of the power supply can be enabled or disabled from the front panel using the key. When the output of the power supply is off, the OFF annunciator turns on and the three outputs are disabled.

• The display provides the present operating status of the power supply with annunciators and also informs the user of error codes. For example, the +6V supply is operating in CV mode and controlled from the front panel, then the CV and +6V annunciators will turn on. If, however, the power supply is remotely controlled, the Rmt annunciator will also turn on, and when the power supply is being addressed over GPIB interface, the Adrs annunciator will turn on. see

Display Limit

Output On/Off

"Display Annunciators"

on page 5 for more information.

Throughout this chapter the key to be pressed is shown in the left margin.

Power

Output On/Off

Chapter 2 Quick Start

To prepare the power supply for use

The following steps help you verify that the power supply is ready for use.

1 Check the list of supplied items.

Verify that you have received the following items with your power supply. If anything is missing, contact your nearest Agilent Technologies Sales Office.

One appropriate power cord for your location.

One User's Guide.

This Service Guide.

Certificate of Calibration.

2 Verify that the correct power-line voltage setting is selected and that

the correct power-line fuse is installed.

The line voltage is set to 100, 115 or 230 Vac from the factory according to the input power option selected when you ordered the power supply. Change the voltage setting if it is not correct for your location (see the next page for detailed information). For 100 or 115 Vac operation, the correct fuse is 2.5 AT (Agilent part number 2110-0913) and for 230 Vac operation, the correct fuse is 2 AT (Agilent part number 2110-0587).

3 Connect the power cord and turn on the power supply.

A power-on self-test occurs automatically when you turn on the power supply. The front-panel display will light up while the power supply performs its power-on self- test. After performing the self-test, the power supply will go into the power-on / reset state; a ll outp u ts are d i sabled (the OFF annunciator turns on); the display is selected for the +6V supply (the +6V annunciator turns on); the knob is selected for voltage control.

4 Enable the outputs

Press the key to enable the outputs. The OFF annunciator turns off and the +6V and CV annunciators are lit. The blinking digit can be adjusted by turning the knob. Notice that the display is in the meter mode. "Meter mode" means that the display shows the actual output voltage and current.

Output On/Off

Chapter 2 Quick Start

To prepare the power supply for use

1 Remove the power cord.

Remove the fuse-holder assembly with a flat-blade screwdriver from the rear panel.

3 Rotate the power-line voltage

selector until the correct voltage appears.

2 Install the corect line fuse.

Remove the power-line voltage selector from the power-line

100 or 115 Vac, 2.5 AT fuse 230 Vac, 2 AT fuse

4 Replace the power-line voltage

selector and the fuse-holder assembly in the rear panel.

100, 115 or 230 Vac

Install the correct fuse and verify that the correct line voltage appears in the window.

Power

Output On/Off

Chapter 2 Quick Start

To check the rated voltages of the power supply

The following procedures check to ensure that the power supply develops its rated voltage outputs with no load and properly responds to operation from the front panel.

For each step, use the keys shown on the left margins.

1 Turn on the power supply.

The power supply will go into the power-on / reset state; all outputs are disabled (the OFF annunciator turns on); the display is selected for the +6V supply (the

+6V annunciator turns on); and the knob is selected for voltage control.

2 Enable the outputs.

The OFF annunciator turns off and the +6V and CV annunciators are lit. The

blinking digit can be adjusted by turning the knob. Notice that the display is in the meter mode. "Meter mode" means that the display shows the actual output voltage and current.

3 Check that the front-panel voltmeter properly responds to knob

control for +6V supply.

Turn the knob clockwise or counter clockwise to check that the voltmeter responds to knob control and the ammeter indicates nearly zero.

4 Ensure that the voltage can be adjusted from zero to the maximum

rated value.

Adjust the knob until the voltmeter indicates 0 volts and then adjust the knob until the voltmeter indicates 6.0 volts.

You can use the resolution selection keys to move the blinking digit to the right or

left when setting the voltage.

Chapter 2 Quick Start

To check the rated voltages of the power supply

+25V

-25V

5 Check the voltage function for the +25V supply.

Select the meter and adjust selection key for the +25V supply. The CV annunciator is still lit and the +25V annunciator will turn on. Repeat steps (3) and (4) to check the voltage function for the +25V supply.

6 Check the voltage function for the -25V supply.

Select the meter and adjust selection key for the -25V supply. The CV annunciator is still lit and the -25V annunciator will turn on. Repeat steps (3) and (4) to check the voltage function for the -25V supply.

Power

Output On/Off

Display Limit

Vol/Cur

Chapter 2 Quick Start

To check the rated currents of the power supply

The following procedures check to ensure that the power supply develops its rated current outputs with a short and properly responds to operation from the front panel.

For each step, use the keys shown on the left margin.

1 Turn on the power supply.

The power supply will go into the power-on / reset state; all outputs are disabled (the OFF annunciator turns on); the display is selected for the +6V supply (the

+6V annunciator turns on); and the knob is selected for voltage control.

2 Connect a short across (+) and (-) output terminals of +6V supply with

an insulated test lead.

3 Enable the outputs.

The OFF annunciator turns off and the +6V annunciator turns on. The CV or CC ann un ci at or is li t d ep en din g o n t he re si st an ce of th e t es t l ea d. Th e blinking

digit can be adjusted by turning the knob. Notice that the display is in the meter mode. "Meter mode" means that the display shows the actual output voltage and current.

4 Adjust the voltage limit value to 1.0 volt.

Set the display to the limit mode (the Lmt annunciator will be blinking). Adjust the voltage limit to 1.0 volt to assure CC operation. The CC annunciator will light.

5 Check that the front-panel ammeter properly responds to knob control

for the +6V supply.

Set the knob to the current control, and turn the knob clockwise or counter clockwise when the display is in the meter mode (the Lmt annunciator is off). Check that the ammeter responds to knob control and the voltmeter indicates nearly zero (actually, the voltmeter will show the voltage drop caused by the test lead).

Chapter 2 Quick Start

To check the rated currents of the power supply

+25V

-25V

Note

6 Ensure that the current can be adjusted from zero to the maximum

rated value.

Adjust the knob until the ammeter indicates 0 amps and then until the ammeter indicates 5.0 amps.

7 Check the current function for the +25V supply.

Disable the outputs by pressing the key and connect a short

Output On/Off

across (+) and (COM) output terminals of the ±25V supply with an insulated test lead. Repeat steps (3) through (6) after selecting the meter and adjust selection key for the +25V supply.

8 Check the current function for the -25V supply.

Disable the outputs by pressing the key and connect a short

Output On/Off

across (-) and (COM) output terminals of the ±25V supply with an insulated test lead. Repeat steps (3) through (6) after selecting the meter and adjust selection key for the -25V supply.

If an error has been detected during the output checkout procedures, the ERROR annunciator will turn on. See "Error Messages" for more information, starting on page 113 in chapter 5 of the User's Guide.

You can use the resolution selection keys to move the blinking digit to the

right or left when setting the current.

Power

Output On/Off

Display Limit

Chapter 2 Quick Start

To use the power supply in constant voltage mode

To set up the power supply for constant voltage (CV) operation, proceed as follows.

For each step, use the keys shown on the left margin.

1 Connect a load to the desired output terminals.

With power-off, connect a load to the desired output terminals.

2 Turn on the power supply.

The power supply will go into the power-on / reset state; all outputs are disabled (the OFF annunciator turns on); the display is selected for the +6V supply (the

+6V annunciator turns on); and the knob is selected for voltage control.

3 Enable the outputs.

The OFF annunciator turns off and the +6V and CV annunciators are lit. The

blinking digit can be adjusted by turning the knob. Notice that the display is in the meter mode. "Meter mode" means that the display shows the actual output voltage and current.

To set up the power supply for +25V supply or -25V supply operation, you should press the or key to select the display and adjust for +25V supply or -25V supply before proceeding to the next step.

4 Set the display for the limit mode.

Notice that the Lmt annunciator blinks, indicating that the display is in the limit mode. When the disp lay is in the limit mode, you can see the voltage and current limit values of the selected supply.

+25V -25V

In constant voltage mode, the voltage values between meter mode and limit mode are the same, but the current values are not. Further if the display is in the meter mode, you cannot see the change of current limit value when adjusting the knob. We recommend that you should set the display to "limit" mode to see the change of current limit value in constant voltage mode whenever adjusting the knob.

Chapter 2 Quick Start

To use the power supply in constant voltage mode

Vol/Cur

Display Limit

Note

5 Adjust the knob for the desired current limit.

Check that the Lmt annunciator still blinks. Set the knob for current control. The second digit of ammeter will be blinking. Adjust the knob to the desired current limit.

6 Adjust the knob for the desired output voltage.

Set the knob for voltage control. The second digit of the voltmeter will be blinking. Adjust the knob to the desired output voltage.

7 Return to the meter mode.

Display Limit

key or let the display time-out after several seconds to return

to the meter mode. Notice that the Lmt annunciator turns off and the display returns to the meter mode. In the meter mode, the display shows the actual output voltage and current of the selected supply.

8 Verify that the power supply is in the constant voltage mode.

If you operate the +6V supply in the constant voltage (CV) mode, verify that CV and +6V annunciators are lit. If you operate the power supply for +25V supply or -25V supply, the +25V or -25V annunciator will turn on. If the CC annunciator is lit, choose a higher current limit.

During actual CV operation, if a load change causes the current limit to be exceeded, the power supply will automatically crossover to constant current mode at the preset current limit and the output voltage will drop proportionately.

You can use the resolution selection keys to move the blinking digit to the right or

left when setting the voltage and current.

Power

Output On/Off

Display Limit

Chapter 2 Quick Start

To use the power supply in constant current mode

To set up the power supply for constant current (CC) operation, proceed as follows.

For each step, use the keys shown on the left margin.

1 Connect a load to the output terminals of the desired supply.

With power-off, connect a load to the desired output terminals.

2 Turn on the power supply.

The power supply will go into the power-on / reset state; all outputs are disabled (the OFF annunciator turns on); the display is selected for the +6V supply (the

+6V annunciator turns on); and the knob is selected for voltage control.

3 Enable the outputs

The OFF annunciator turns off and the +6V and CV annunciators are lit. The

blinking digit can be adjusted by turning the knob. Notice that the display is in the meter mode. "Meter mode" means that the display shows the actual output voltage and current.

To set up the power supply for +25V supply or -25V supply operation, you should press the or key to select the display and adjust for +25V supply or -25V supply before proceeding to the next step.

4 Set the display for the limit mode.

+25V -25V

In constant current mode, the current values between meter mode and limit mode are the same, but the voltage values are not. Further if the display is in the meter mode, you cannot see the change of voltage limit value when adjusting the knob. We recommend that you should set the display to "limit" mode to see the change of voltage limit value in constant current mode whenever adjusting the knob.

Chapter 2 Quick Start

To use the power supply in constant current mode

Vol/Cur

Display Limit

Note

5 Adjust the knob for the desired voltage limit.

Check that the knob is still selected for voltage control and the Lmt annunciator blinks. Adjust the knob for the desired voltage limit.

6 Adjust the knob for the desired output current.

Set the knob for current control. The second digit of the ammeter will be blinking. Adjust the knob to the desired current output.

7 Return to the meter mode.

Press the key or let the display time-out after several seconds

Display Limit

to return the meter mode. Notice that the Lmt annunciator turns off and the display returns to the meter mode. In the meter mode, the display shows the actual output voltage and current of the selected supply.

8 Verify that the power supply is in the constant current mode.

If you operate the +6V supply in the constant current (CC) mode, verify that CC and +6V annunciators are lit. If you operate the power supply for +25V supply or -25V supply, the +25V or -25V annunciator will turn on. If the CV annunciator is lit, choose a higher voltage limit.

During actual CC operation, if a load change causes the voltage limit to be exceeded, the power supply will automatically crossover to constant voltage mode at the preset voltage limit and the output current will drop proportionately.

You can use the resolution selection keys to move the blinking digit to the right or

left when setting the voltage and current.

Track

Chapter 2 Quick Start

To use the power supply in track mode

The ±25V supplies provide 0 to ±25 V tracking outputs. In the track mode, two voltages of the ±25V supplies track each other to within ±(0.2% of output + 20 mV) for convenience in varying the symmetrical voltages needed by operational amplifiers and other circuits using balanced positive and negative inputs.

To operate the power supply in the track mode, proceed as follows:

1 Set the +25V supply to the desired voltage as described in previous

section "To use the power supply in constant voltage mode" (see page 29 for detailed information).

2 Enable the track mode.

Track

The key must be depressed for at least 1 second to enable the track mode. When the track mode is first enabled, the -25V supply will be set to the same voltage level as the +25V supply. Once enabled, any change of the voltage level in either the +25V supply or the -25V supply will be reflected in other supply. The current limit is independently set for each of the +25V or the -25V supply and is not affected by the track mode.

3 Verify that ±25V supplies track each other properly.

You can verify that the voltage of the -25V supply tracks that of the +25V supply within ±(0.2% of output + 20 mV) from the front-panel display by comparing the voltage values of the +25V supply and the -25V supply.

In the track mode, if the CC annunciator is lit when the display is selected for the +25V supply, choose a higher current limit for the +25V supply. If the CC annunciator is lit when the display is selected for the

-25V supply, choose a higher current limit for the -25V supply.

Store

Chapter 2 Quick Start

To store and recall the instrument state

You can store up to three different operating states in non-volatile memory. This also enables you to recall the entire instrument state with just a few key presses from the front panel.

The memory locations are supplied from the factory for front panel operation with the following states: display and knob selection for +6V output; *RST

values of voltage and current limits for three outputs; output disabled; and track off state. *RST values for +6V supply are 0 V and 5 A and 0 V and 1 A for the ±25V supplies.

The following steps show you how to store and recall an operating state.

1 Set up the power supply for the desired operating state.

The storage feature "remembers" the display and knob selection state, the limit values of voltage and current for three outputs, output on/off state, and track mode state.

2 Turn on the storage mode.

Three memory locations (numbered 1, 2, and 3) are available to store the operating states. The operating states are stored in non-volatile memory and are remembered when being recalled.

Store 1

This message appears on the display for approximately 3 seconds.

3 Store the operating state in memory location "3".

Turn the knob to the right to specify the memory location 3.

Store 3

To cancel the store operation, let the display time-out after 3 seconds or press any other function key except the key. The power supply returns to the normal operating mode and to the function pressed.

Store

Chapter 2 Quick Start

To store and recall the instrument state

Store

Recall

4 Save the operating state.

The operating state is now stored. To recall the stored state, go to the following steps.

done

This message appears on the display for approximately 1 second.

5 Turn on the recall mode.

Memory location "1" will be displayed in the recall mode.

recall 1

This message appears on the display for approximately 3 seconds.

6 Recall the stored operating state.

Turn the knob to the right to change the displayed storage location to "3".

recall 3

If this setting is not followed within 3 seconds with a key stroke, the power supply returns to normal operating mode and will not recall the instrument state 3 from memory.

7 Restore the operating state.

The power supply should now be configured in the same state as when you stored the state on the previous steps.

Recall

done

This message appears on the display for approximately 1 second.

Chapter 2

Quick Start

To rack mount the power supply

The power supply can be mounted in a standard 19-inch rack cabinet using one of three optional kits available. A rack-mounting kit for a single instrument is available as Option 1CM (P/N 5062-3957). Installation instructions and hardware are included with each rack-mounting kit. Any Agilent Technologies System II instrument of the same size can be rack-mounted beside the Agilent E3631A power supply. To rack mount the power supply, follow these procedures.

Remove the front and rear bumpers before rack-mounting the power supply.

Front

To remove the rubber bumper, stretch a corner and then slide it off.

To rack mount a single instrument, order adapter kit 5063-9243.

Rear (bottom view)

Chapter 2

Quick Start

To rack mount the power supply

To rack mount two instruments of the same depth side-by-side, order lock-link kit 5061-9694 and flange kit 5063-9214.

To install two instruments in a sliding support shelf, order suport shelf 50639256, and slide kit 1494-0015.

Chapter 2 Quick Start

To rack mount the power supply

Calibration Procedures

This chapter contains procedures for verification of the power supply's performance and calibration (adjustment). The chapter is divided into the following sections:

• Agilent Technologies Calibration Services, page 41

• Calibration Interval, page 41

• Automating Calibration Procedures, page 42

• Recommended Test Equipment, page 42

• Test Considerations, page 43

• Performance Verification Tests, page 44

• Measurement Techniques, page 45

• Constant Voltage (CV) Verifications, page 47

• Constant Current (CC) Verifications, page 54

• Performance Test Record for Agilent E3631A, page 59

• Calibration Security Code, page 61

• Calibration Count, page 65

• Calibration Message, page 65

• General Calibration/Adjustment Procedure, page 66

• Aborting a Calibration in Progress, page 71

• Calibration Record for Agilent E3631A, page 72

• Error Messages, page 73

• Calibration Program, page 75

The performance verification tests for constant voltage (CV) and constant current (CC) operations use the power supply's specifications listed in chapter 1, Specifications, starting on page 13.

Chapter 3 Calibration Procedures

Agilent Technologies Calibration Services

Closed-Case Electronic Calibration The power supply features closedcase electronic calibration since no internal mechanical adjustments are required for normal calibration. The power supply calculates correction factors based upon the input reference value you enter. The new correction factors are stored in non-volatile memory until the next calibration adjustment is performed. (Non-volatile memory does not change when power has been off or after a remote interface reset.)

Agilent Technologies Calibration Services

When your power supply is due for calibration, contact your local Agilent Technologies Service Center for a low-cost calibration. The Agilent E3631A power supply is supported on calibration processes which allow Agilent Technologies to provide this service at competitive prices.

Calibration Interval

The power supply should be calibrated on a regular interval determined by the accuracy requirements of your application. A 1-year interval is adequate for most applications. Agilent Technologies does not recommend extending calibration intervals beyond 1 year for any application. Agilent Technologies recommends that complete re-adjustment should always be performed at the calibration interval. This will increase your confidence that the Agilent E3631A will remain within specification for the next calibration interval. This criteria for re-adjustment provides the best long-term stability.

Chapter 3

Calibration Procedures

Automating Calibration Procedures

You can automate the complete verification procedures outlined in this chapter if you have access to programmable test equipment. You can program the instrument configurations specified for each test over the remote interface. You can then enter readback verification data into a test program and compare the results to the appropriate test limit values.

You can also enter calibration constants from the remote interface. Remote operation is similar to the local front-panel procedure. You can use a computer to perform the adjustment by first selecting the required setup. The calibration value is sent to the power supply and then the calibration is initiated over the remote interface. The power supply must be unsecured prior to initiating the calibration procedure. An Agilent BASIC program for calibration over the GPIB interface is listed at the end of this chapter.

For further details on programming the power supply, see chapters 3 and 4 in the Agilent E3631A User's Guide.

Recommended Test Equipment

The test equipment recommended for the performance verification and adjustment procedures is listed below. If the exact instrument is not available, use the accuracy requirements shown to select substitute calibration standards.

Table 3-1 Recommended Test Equipment

Instrument Requirements

GPIB Controller Full GPIB capabilities

Oscilloscope 100 MHz Agilent 54602A

RMS Voltmeter 20 MHz Measure rms ripple & noise Digital Voltmeter

Electronic Load

Resistive Loads (RL) Current monitoring

Resistor (Shunt)

Resolution: 0.1 mV Accuracy: 0.01%

Voltage Range: 50 Vdc Current Range: 10 Adc Open and Short Switches Transient On/Off

1.2Ω, 100 W 25Ω, 100 W

0.1Ω, 0.01% Constant current test setup

Recommended

Model

Agilent 82341C interface card

Agilent 34401A Measure dc voltages

Agilent 6063A

Programming and readback accuracy

Display transient response and ripple & noise waveform

Measure load and line regulations and transient response time.

Measure ripple and noise

Use

Chapter 3 Calibration Procedures

Test Considerations

To ensure proper instrument operation, verify that you have selected the correct power-line voltage prior to attempting any test procedure in this chapter. See page 24 in chapter 2 for more information.

• Assure that the calibration ambient temperature is stable and between 20°C and 30°C.

• Assure ambient relative humidity is less than 80%.

• Allow a 1-hour warm-up period before verification or calibration.

• Keep cables as short as possible, consistent with the impedance requirements.

Caution The tests should be performed by qualified personnel. During performance

verification tests, hazardous voltages may be present at the outputs of the power supply.

Chapter 3 Calibration Procedures

Performance Verification Tests

The performance verification tests use the power supply's specifications listed in chapter 1, "Specifications", starting on page 13.

You can perform two different levels of performance verification tests:

• Self-Test A series of internal verification tests that provide high

confidence that the power supply is operational.

• Performance Verification Tests These tests can be used to verify the

power supply's specifications following repairs to specific circuits. The performance test procedures must be performed on each output.

Self-Test

A powe r-on self-test occurs automatically when you turn on the power supply. This limited test assures you that the power supply is operational.

The complete self-test is enabled by pressing the key (actually any front panel keys except the key) and the power-line switch simultaneously and then continuing to press the key for 5 seconds. The complete self-test will be finished in 2 more seconds.

You can also perform a self-test from the remote interface (see chapter 3 in the Agilent E3631A User's Guide).

• If the self-test is successful, "PASS" is displayed on the front panel.

• If the self-test fails, "FAIL" is displayed and the ERROR annunciator turns

on. If repair is required, see chapter 5, "Service", starting on page 91, for further details.

• If self-test passes, you have a high confidence that the power supply is operational.

Error

Recall

Performance Verification Tests

These tests can be used to verify the power supply's specifications following repairs to specific circuits. The following sections explain all verification procedures in detail. All of the performance test specifications are shown in each test.

Chapter 3

Calibration Procedures

Measurement Techniques

Setup for Most Tests

Most tests are performed at the front terminals as shown in the following figure. Measure the dc voltage directly at the (+) and (-) terminals on the front panel.

Figure 3-1. Performance Verification Test Setup

Electronic Load

Many of the test procedures require the use of a variable load resistor capable of dissipating the required power. Using a variable load resistor requires that switches be used to connect, disconnect, and short the load resistor. An electronic load, if available, can be used in place of a variable load resistor and switches. The electronic load is considerably easier to use than load resistors. It eliminates the need for connecting resistors or rheostats in parallel to handle power, it is much more stable than carbon-pile load, and it makes easy work of switching between load conditions as is required for the load regulation and load transient response tests. Substitution of the electronic load requires minor changes to the test procedures in this chapter.

General Measurement Techniques

To achieve best results when measuring load regulation, peak to peak voltage, and transient response time of the power supply, measuring devices must be connected through the hole in the neck of the binding post at (A) while the

Chapter 3

Calibration Procedures

Measurement Techniques

load resistor is plugged into the front of the output terminals at (B). A measurement made across the load includes the impedance of the leads to the load. The impedance of the load leads can easily be several orders of the magnitude greater than the power supply impedance and thus invalidate the measurement. To avoid mutual coupling effects, each measuring device must be connected directly to the output terminals by separate pairs of leads.

Front Panel Terminal Connections (Side View)

Current-Monitoring Resistor

To eliminate output current measurement error caused by the voltage drops in the leads and connections, connect the current monitoring resistor between the (-) output terminal and the load as a four-terminal device. Connect the current-monitoring leads inside the load-lead connections directly at the monitoring points on the resistor element (see RM in Figure 3-1).

Programming

Most performance tests can be performed only from the front panel. However, a GPIB or RS-232 controller is required to perform the voltage and current programming accuracy and readback accuracy tests.

The test procedures are written assuming that you know how to program the power supply either from the front panel or from an GPIB or RS-232 controller. Complete instructions on front panel and remote programming are given in the Agilent E3631A User's Guide.

Voltage and Current Values

The full-scale and maximum values of each supply are listed below. You can use this table when you test CV and CC performance verification tests.

Table 3-2 Power Supply Voltage and Current Values

Output

+6V Output +6 V +6.18 V 5 A 5.15 A +25V Output +25 V +25.75 1 A 1.03 A

-25V Output -25 V -25.75 1 A 1.03 A

Full-Scale

Voltage

Max. Prog.

Voltage

Full-Scale

Current

Max. Prog.

Current

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

Constant Voltage Test Setup

If more than one meter or a meter and an oscilloscope are used, connect each to the (+) and (- ) terminals b y a sepa rate pai r of leads to a void mutua l coupling effects. Use coaxial cable or shielded 2-wire cable to avoid noise pick-up on the test leads.

Voltage Programming and Readback Accuracy

This test verifies that the voltage programming and GPIB or RS-232 readback functions are within specifications. Note that the readback values over the remote interface should be identical to those displayed on the front panel.

You should program the power supply over the remote interface for this test to avoid round off errors.

Turn off the power supply and connect a digital voltmeter between the (+) and

(-) terminals of the output to be tested as shown in Figure 3-1.

Turn on the power supply. Enable the outputs and select the desired output to

be tested by sending the commands:

OUTP ON INST {P6V|P25V|N25V}

Program the selected output to zero volts and maximum programmable

current (see Table 3-2) by sending the commands:

VOLT 0 CURR 5.15 CURR 1.03

Record the output voltage reading on the digital voltmeter (DVM). The readings

should be within the limits specified below for each output tested. Also, note that the CV, Adrs, Lmt, and Rmt annunciators are on.

Output Programming Accuracy

+6V 0 ± 5 mV

+25V 0

-25V 0

± 20 mV ± 20 mV

for the +6V supply or for the ±25V supply

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

Readback the output voltage of the selected output over the remote interface

by sending the command:

MEAS:VOLT? {P6V|P25V|N25V}

Record the value displayed on the controller. This value should be within the

limits specified below for each output tested.

Output Programming Accuracy

+6V DVM ± 5 mV

+25V DVM

-25V -(DVM

Program the selected output's voltage to full scale value by sending the

± 10 mV

± 10 mV)

commands.

VOLT 6.0 VOLT 25.0

Record the output voltage reading on the digital voltmeter (DVM). The readings

for the +6V supply or

for the ± 25V supply

should be within the limits specified below for each output tested.

Output Programming Accuracy

+6V 6 V ± 11 mV

+25V 25 V

-25V -(25 V

Readback the output voltage of the selected output over the remote interface

± 32.5 mV

± 32.5 mV)

by sending the command:

MEAS:VOLT? {P6V|P25V|N25V}

Record the value displayed on the controller. This value should be within the

limits specified below for the output to be tested.

Output Programming Accuracy

+6V DVM ± 11 mV

+25V DVM

-25V -(DVM

Repeat steps (1) through (10) for the remaining outputs.

± 22.5 mV

± 22.5 mV)

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

CV Load Regulation

This test measures the change in the output voltage resulting from a change in the output current from full to no load.

Turn off the power supply and connect a digital voltmeter between the (+) and

(-) terminals of the output to be tested as shown in Figure 3-1.

Turn on the power supply and select the desired output to be tested using the

meter and adjust selection key on the front panel. Enable the outputs and set the display to the limit mode. When the display is in the limit mode, program the current of the selected output to the maximum programmable value and the voltage to the full-scale value (see Table 3-2).

Operate the electronic load in constant current mode and set its current to the

full scale value of the output to be tested (see Table 3-2). Check that the front panel CV annunciator remains lit. If not lit, adjust the load so that the output current drops slightly until the CV annunciator lights. Record the output voltage reading on the digital voltmeter.

Operate the electronic load in open mode (input off). Record the output voltage

reading on the digital voltmeter again. The difference between the digital voltmeter readings in steps (3) and (4) is the CV load regulation. The difference of the readings should be within the limit specified below for each output tested.

Output Programming Accuracy

+6V 2.6 mV

+25V 4.5 mV

-25V 4.5 mV

Repeat steps (1) through (4) for the remaining outputs.

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

CV Line Regulation

This test measures the change in output voltage that results from a change in ac line voltage from the minimum value (10% below the nominal input voltage) to maximum value (10% above the nominal input voltage).

Turn off the power supply and connect a digital voltmeter between the (+) and

(-) terminals of the output to be tested as shown in Figure 3-1.

Connect the ac power line through a variable voltage transformer.

Turn on the power supply and select the desired output to be tested using the

Operate the electronic load in constant current mode and set its current to the

full scale value (see Table 3-2) of the output to be tested. Check that the front panel CV annunciator remains lit. If not lit, adjust the load so that the output current drops slightly until the CV annunciator lights.

Adjust the transformer to low line voltage limit (104 Vac for nominal 115 Vac,

90 Va c f or no mi nal 10 0 V ac , o r 20 7 V ac fo r n omin al 23 0 Vac ). Re co rd th e o ut pu t reading on the digital voltmeter.

Adjust the autotranformer to high line voltage (127 Vac for nominal 115 Vac,

110 Vac for nominal 100 Vac, or 253 Vac for nominal 230 Vac). Record the voltage reading on the digital voltmeter. The difference between the digital voltmeter readings in steps (5) and (6) is the CV line regulation. The difference of the readings should be within the limit specified below for each output tested.

Output Difference

+6V 2.6 mV

+25V 4.5 mV

-25V 4.5 mV

Repeat steps (1) through (6) for the remaining outputs.

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

Normal Mode Voltage Noise (CV Ripple and Noise)

The normal mode voltage noise is in the form of ripple related to the line frequency plus some random noise. The normal mode voltage noise is specified as the rms or peak-to-peak output voltage in a frequency range from 20 Hz to 20 MHz.

Turn off the power supply and connect the output to be tested as shown in Figure

3-1 to an oscilloscope (ac coupled) between (+) and (-) terminals. Set the oscilloscope to AC mode and bandwidth limit to 20 MHz. Connect a resistive load (1.2 for +6V supply and 25 for ±25V supplies) as shown in Figure 3-1 (see Table 3-2).

Turn on the power supply and select the output to be tested using the meter

and adjust selection key on the front panel. Enable the outputs and set the display to the limit mode. When the display is in the limit mode, program the current of the selected output to the maximum programmable value and the voltage to the full-scale value (see Table 3-2).

Check that the front panel CV annunciator remains lit. If not lit, adjust the load

down slightly.

Note that the waveform on the oscilloscope does not exceed the peak-to-peak

limit of 2 mV for each of the three outputs.

Disconnect the oscilloscope and connect an AC rms voltmeter in its place. The

rms voltage reading does not exceed the rms limit of 0.35 mV for each of the three outputs.

Repeat steps (1) through (5) for the remaining outputs.

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

Common Mode Current Noise

The common mode current is that ac current component which exists between any or all outputs or output lines and chassis ground. Common mode noise can be a problem for very sensitive circuitry that is referenced to earth ground. When a circuit is re ference d to earth grou nd, a low level lin e-relate d ac curr ent will flow from the output terminals to earth ground. Any impedance to earth ground will create a voltage drop equal to the output current flow multiplied by the impedance.

Turn off the power supply and connect a 100 k resistor (R

) and a 2200 pF

capacitor in parallel between the (-) terminal and chassis ground for +6V output or between the (COM) terminal and chassis ground for ±25V outputs.

Connect a digital voltmeter across R

Turn on the power supply and select the output to be tested using the meter

Record the voltage across R

and convert it to current by dividing by the

resistance (DVM reading/100 k). Note that the current is less than 1.5 A for each of the three outputs.

Repeat steps (1) through (4) for the remaining outputs.

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

Load Transient Response Time

This test measures the time for the output voltage to recover to within 15 mV of nominal output voltage following a load change from full load to half load, or half load to full load.

Turn off the power supply and connect the output to be tested as shown in Figure

3-1 with an oscilloscope. Operate the electronic load in constant current mode.

Turn on the power supply and select the output to be tested using the meter

and adjust selection key on the front panel. Enable the outputs and set the display to the limit mode. When the display is in the limit mode, program the current to the maximum programmable value and the voltage to the full-scale value (see Table 3-2).

Set the electronic load to transient operation mode between one half of the

output's full scale value and the output's full scale value at a 1 kHz rate with 50% duty cycle.

Set the the oscilloscope for ac coupling, internal sync, and lock on either the

positive or negative load transient.

Adjust the the oscilloscope to display transients as shown in Figure 3-2. Note

that the pulse width (t more than 50 msec for each of the three outputs.

Repeat steps (1) through (5) for the remaining outputs.

) of the transients at 15 mV from the base line is no

2-t1

Figure 3-2. Transient Response Time

Chapter 3 Calibration Procedures

Constant Current (CC) Verifications

Constant Current Test Setup

Follow the general setup instructions in the "Measurement Techniques" section starting on page 45 and the specific instructions will be given in the following paragraphs.

Current Programming and Readback Accuracy

This test verifies that the current programming and GPIB or RS-232 readback functions are within specifications. Note that the readback values over the remote interface should be identical to those displayed on the front panel. The accuracy of the current monitoring resistor must be 0.1% or better.

You should program the power supply over the remote interface for this test to avoid round off errors.

Turn off the power supply and connect a 0.1

9 current monitoring resistor (R

across the output to be tested and a digital voltmeter across the current monitoring resistor (R

Turn on the power supply. Enable the outputs and select the desired output to

be tested by sending the commands:

OUTP ON INST {P6V|P25V|N25V}

Program the selected output voltage to 5.0 volts and the current to 0 amps by

sending the commands:

VOLT 5 CURR 0

Divide the voltage drop (DVM reading) across the current monitoring resistor

) by its resistance to convert to amps and record this value (IO). This value

should be within the limits specified below for each output tested. Also, note that the CC, Adrs, Lmt, and Rmt annunciators are on.

Output Programming Accuracy

+6V 0 A ± 10 mA

+25V 0 A

-25V 0 A

± 4 mA ± 4 mA

)

Chapter 3 Calibration Procedures

Constant Current (CC) Verifications

Readback the output current from the selected output over the remote

interface by sending the command:

MEAS:CURR? {P6V|P25V|N25V}

Record the value displayed on the controller. This value should be within the

limits specified below for each output tested.

Output Readback Accuracy

+6V I

+25V I

-25V I

Program the selected output current to the full scale value (see Table 3-2) by

± 10 mA

± 4 mA

sending the commands:

CURR 5.0 CURR 1.0

Divide the voltage drop (DVM reading) across the current monitoring resistor

) by its resistance to convert to amps and record this value (IO). This value

for the +6V supply or for the ±25V supply

should be within the limits specified below for each output tested.

Output Programming Accuracy

+6V 5 A ± 20 mA

+25V 1 A

-25V 1 A

Readback the output current from the selected output over the remote

± 5.5 mA ± 5.5 mA

interface by sending the command:

MEAS:CURR? {P6V|P25V|N25V}

Record the value displayed on the controller. This value should be within the

limits specified below for each output tested.

Output Readback Accuracy

+6V I

+25V I

-25V I

Repeat steps (1) through (10) for the remaining outputs.

± 20 mA

± 5.5 mA

Chapter 3 Calibration Procedures

Constant Current (CC) Verifications

CC Load Regulation

Th is test m e asures th e change in ou tpu t curren t re sul tin g from a cha nge in th e load from full-scale output voltage to short circuit.

Turn off the power supply and connect the output to tested as shown in Figure

3-1 with the digital voltmeter connected across the 0.1 resistor (R

Turn on the power supply and select the desired output to be tested using the

meter and adjust selection key on the front panel. Enable the outputs and set the display to the limit mode. When the display is in the limit mode, program the voltage to the maximum programmable value and the current to the fullscale value (see Table 3-2).

Opera te the el ectronic load in constant voltag e mode and set its voltage to the

full scale value of the output to be tested (see Table 3-2). Check that the CC annunciator is on. If it is not, adjust the load so that the output voltage drops slightly. Record the current reading by dividing the voltage reading on the digital voltmeter by the resistance of the current monitoring resistor.

9 current monitoring

Operate the electronic load in short (input short) mode. Record the current

reading again by dividing the voltage reading on the digital voltmeter by the resistance of the current monitoring resistor. The difference between the current readings in step (3) and (4) is the load regulation current. The difference of the readings should be within the limit specified below for each output tested.

Output Difference

+6V 0.75 mA

+25V 0.35 mA

-25V 0.35 mA

Repeat steps (1) through (4) for the remaining outputs.

Chapter 3 Calibration Procedures

Constant Current (CC) Verifications

CC Line Regulation

This test measures the change in output current that results from a change in ac line voltage from the minimum value (10% below the nominal input voltage) to the maximum value (10% above nominal voltage).

Turn off the power supply and connect the output to be tested as shown in Figure

3-1 with the digital voltmeter connected across the current monitoring resistor

Connect the ac power line through a variable voltage transformer.

Turn on the power supply and select the desired output to be tested using the

meter selection key on the front panel. Enable the outputs and set the display to the limit mode. When the display is in the limit mode, program the voltage to the maximum programmable value and the current to the full-scale value (see Table 3-2).

Opera te the el ectronic load in constant voltag e mode and set its voltage to the

full scale value of the output to be tested (see Table 3-2). Check that the CC annunciator remains lit. If not lit, adjust the load so that the output voltage drops slightly until the CC annunciator lights.

Adjust the transformer to low line voltage limit (104 Vac for nominal 115 Vac,

90 Va c f or no mi nal 10 0 V ac , o r 20 7 V ac fo r n omin al 23 0 Vac ). Re co rd th e o ut pu t current reading by dividing the voltage reading on the digital voltmeter by the resistance of the current monitoring resistor.

Adjust the transformer to 10% above the nominal line voltage (110 Vac for a

100 Vac nominal input, 127 Vac for a 115 Vac nominal input or 253 Vac for a 230 Vac nominal input). Record the current reading again by dividing the voltage reading on the digital voltmeter by the resistance of the current monitoring resistor. The difference between the current readings in step (5) and (6) is the load regulation current. The difference of the readings should be within the limit specified below for each output tested.

Output Difference

+6V 0.75 mA

+25V 0.35 mA

-25V 0.35 mA

Repeat steps (1) through (6) for the remaining outputs.

Chapter 3 Calibration Procedures

Constant Current (CC) Verifications

Normal Mode Current Noise (CC Ripple and Noise)

The normal mode current noise is specified as the rms output current in a frequency range 20 Hz to 20 MHz with the power supply in constant current operation.

Turn off the power supply and connect the output to be tested as shown in Figure

3-1 with a load resistor (1.29 for +6V supply and 259 for ±25V supplies) across output terminals to be tested. Connect a rms voltmeter across the load resistor. Use only a resistive load for this test.

Turn on the power supply and select the output to be tested using the meter

selection key on the front panel. Enable the outputs and set the display to the limit mode. When the display is in the limit mode, program the current to fullscale value and the voltage to the maximum programmable value.

The output current should be at the full-scale rating with the CC annunciator

on. If not lit, adjust the load so that the output voltage drops slightly until the CC annunciator lights.

Divide the reading on the rms voltmeter by the load resistance to obtain rms

current. The readings should be within the limit specified below for each output tested.

Output Specification

+6V 2 mA

+25V 0.5 mA

-25V 0.5 mA

Repeat steps (1) through (4) for the remaining outputs.

Chapter 3 Calibration Procedures

Performance Test Record for Agilent E3631A

CV Performance Test Record

Test Description

CV Programming A ccuracy @ 0 volts

(DVM reading) +6V supply +25V supply

-25V supply

CV Readback Accuracy @ 0 volts

+6V supply +25V supply

-25V supply

CV Programming Accuracy @ Fu ll Sc al e

(DVM reading) +6V supply +25V supply

-25V supply

CV Readback Accuracy @ Full Scale +6V supply +25V supply

-25V supply

CV Load Regulation

+6V supply +25V supply

-25V supply

CV Line Regulation

+6V supply +25V supply

-25V supply

CV Ripple/Noise

+6V supply +25V supply

-25V supply

CV Current Noise (Common Mode) +6V supply +25V supply

-25V supply

Load Transient Response Time

+6V supply +25V supply

-25V supply

Actual Result

Specifications

Upper Limit Lower Limit

+0.0050 V +0.0200 V +0.0200 V

DVM + 0.0050 V DVM + 0.0100 V

-(DVM + 0.0100) V

6.0110 V

25.0325 V

-25.0325 V

DVM + 0.0110 V DVM + 0.0225 V

-(DVM + 0.0225) V

Maximum change: <2.6 mV <4.5 mV <4.5 mV

<2 mV p-p, 0.35 mV rms for each of the three outputs

<1.5 mA for each of the three outputs

<50 msec for each of three outputs

-0.0050 V

-0.0200 V

DVM - 0.0050 V DVM - 0.0100 V

-(DVM - 0.0100) V

5.9890 V

24.9675 V

-24.9675 V

DVM - 0.0110 V DVM - 0.0225 V

-(DVM - 0.0225) V

Chapter 3 Calibration Procedures

Performance Test Record for Agilent E3631A

CC Performance Test Record

Test Description

CC Programming Accuracy @ 0 amps (IO) +6V supply +25V supply

-25V supply

CC Readback Accuracy @ 0 amps +6V supply +25V supply

-25V supply

CC Programming Accuracy @ Full Scale (I +6V supply +25V supply

-25V supply

CC Readback Accuracy @ Full Scale +6V supply +25V supply

-25V supply

CC Load Regulation

+6V supply +25V supply

-25V supply

CC Line Regulation

+6V supply +25V supply

-25V supply

CC Ripple/Noise

+6V supply +25V supply

-25V supply

)

Actual Result

Specifications

Upper Limit Lower Limit

+0.0100 A +0.0040 A +0.0040 A

+ 0.0100 A

+ 0.0040 A

5.0200 A

1.0055 A

+ 0.0200 A

+ 0.0055 A

-0.0100 A

-0.0040 A

- 0.0100 A

- 0.0040 A

4.9800 A

0.9945 A

- 0.0200 A

- 0.0055 A

Maximum change: <0.75 mA <0.35 mA <0.35 mA

<2 mA <0.5 mA <0.5 mA

Chapter 3 Calibration Procedures

Calibration Security Code

This feature allows you to enter a security code (electronic key) to prevent accidental or unauthorized calibrations of the power supply. When you first receive your power supply, it is secured. Before you can calibrate the power supply, you must unsecure it by entering the correct security code. A procedure to unsecure the power supply is given on the following page.

• The security code is set to "HP003631" when the power supply is shipped

from the factory. The security code is stored in non-volatile memory, and does not change when power has been off or after a remote interface reset.

• To secure the power supply from the remote interface, the security code may contain up to 12 alphanumeric characters as shown below. The first character must be a letter, but the remaining characters can be letters or numbers. You do not have to use all 12 characters but the first character must always be a letter.

A _ _ _ _ _ _ _ _ _ _ _ (12 characters)

• To secure the power supply from the remote interface so that it can be unsecured from the front panel, use the eight-character format shown below. The first two characters must be "H P" and the remaining characters must be numbers. Only the last six characters are recognized from the front panel, but all eight characters are required. To unsecure the power supply

from the front panel, omit the "H P" and enter the remaining numbers as shown on the following pages.

H P _ _ _ _ _ _ (8 characters)

• If you forget your security code, you can disable the security feature by adding a jumper inside the power supply, and then entering a new code. See

the procedure on page 64.

Calibrate

Power

Chapter 3 Calibration Procedures

Calibration Security Code

To Unsecure the Power Supply for Calibration

The power supply can use a calibration security code to prevent unauthorized or accidental calibration. This procedure shows you how to unsecure the power supply for calibration from the front panel.

Turn on the front-panel calibration mode.

secured

Turn on the calibration mode by pressing the "Calibrate" key while simultaneously turning on the power supply then continue to hold the "Calibrate" key for about 5 seconds until a beep is heard.

If the power supply is secured, you will see the above message from the front panel for approximately one second. The "CAL MODE'' message is then displayed on the front panel.

Secure

Move to the security code by pressing the "Secure" key.

000000 code

Enter the security code using the knob and resolution selection keys.

003631 code

The security code is set to "HP003631" when the power supply is shipped from the factory. The security code is stored in non-volatile memory and does not change when the power has been off or after a remote interface reset.

To enter the security code from the front panel, enter only the last six digits. To enter the security code from the remote interface, you may enter up to 12 characters.

Use the resolution selection keys to move left or right between digits. Use the knob to change the digits. Notice that the security code may be different if the security code has been changed from the default setting.

Chapter 3 Calibration Procedures

Calibration Security Code

Secure

Power

Unsecure the power supply.

unsecured

The power supply is unsecured when you press the key. You will see the above message from the front panel for one second. The "CAL MODE" message is displayed on the front panel after above message.

Turn off the calibration mode.

Turn off the power supply to exit the calibration mode.

To re-secure the power supply (following calibration), perform this procedure again.

Secure

Chapter 3 Calibration Procedures

Calibration Security Code

To Unsecure the Power Supply Without the Security Code

To unsecure the power supply without the correct security code (when you forget the security code), follow the steps below. See "Electrostatic Discharge (ESD) Precautions" in chapter 5 before beginning this procedure.

Disconnect the power cord and all load connections from front terminals.

Remove the instrument cover. Refer to the disassembly drawing on page 123.

Connect the power cord and turn on the calibration mode by pressing the

"Calibrate" key while simultaneously turning on the power supply then continue to hold the "Calibrate" key for about 5 seconds until a beep is heard. Be careful not to touch the power line connections.

Apply a short between the two exposed metal pads on JP1 (located near main

controller U17 on the top board). The exposed metal pads are outlined with a small rectangular silkscreen. (See the component locator drawing for the E3631-60002 top PC board on page 124.)

While maintainin g the short, move to the security code and e nter any un secure

code in the calibration mode. The power supply is now unsecured.

Remove the short at JP1. (An error occurs if not removed.)

Turn off and reassemble the power supply.

Now you can enter a new security code. Be sure you take note of the new security code.

Chapter 3 Calibration Procedures

Calibration Count

The calibration count feature provides an independent "serialization" of your calibrations. You can determine the number of times that your power supply has been calibrated. By monitoring the calibration count, you can determine whether an unauthorized calibration has been performed. Since the value increments by one for each calibration parameter (see Table 3-3 on the next page), a complete calibration increases the value by 6 counts.

• The calibration count is stored in non-volatile memory and does not change when power has been off or after a remote interface reset. Your power supply was calibrated before it left the factory. When you receive the power supply, read the calibration count to determine its value.

• The calibration count increments up to a maximum of 32,767 after which it wraps around to 0. No way is provided to program or reset the calibration count.

Calibration Message

You can use the calibration message feature to record calibration information about your power supply. For example, you can store such information as the last calibration date, the next calibration due date, the power supply's serial number, or even the name and phone number of the person to contact for a new calibration.

You can record and read information in the calibration message from the remote interface only.

• The calibration message may contain up to 40 characters.

• The calibration message is stored in non-volatile memory and does not change when power has been off or after a remote interface reset.

Chapter 3 Calibration Procedures

General Calibration/Adjustment Procedure

The calibration procedures from the front panel are described in this section. For output voltage calibration, disconnect all loads from the power supply and connect a DVM across the output terminals to be calibrated. For output current calibration, disconnect all loads from the power supply, connect an appropriate current monitoring resistor across the output terminals to be calibrated, and connect a DVM across the terminals of the monitoring resistor.

The following table shows calibration parameters and points which should be used to calibrate the output voltage and current for each of the three outputs.

Table 3-3. Parameters for Calibration

Output Calibration Parameter

CAL SETUP 1 Voltage

+6V output

CAL SETUP 2 Current

CAL SETUP 3 Voltage

+25V output

CAL SETUP 4 Current

CAL SETUP 5 Voltage

-25V output

CAL SETUP 6 Current

Voltage/

Current

Calibration Point

mnemonic

V LO

V HI

I LO

I HI

V LO

V HI

V LO

I HI

V LO

V HI

I LO

I HI

Note You can terminate any CAL SETUP without changing its calibration constants by

turning off power.

Chapter 3 Calibration Procedures

General Calibration/Adjustment Procedure

To calibrate the output voltages and currents of the power supply from the front panel, proceed as follows:

Unsecure the power supply.

To calibrate the output voltage and current, you must unsecure the power supply according to the procedure given on page 62.

Disconnect all loads from the power supply and connect a DVM across

output terminals of the +6V output.

Calibrate

Power

Calibrate

Turn on the calibration mode.

cal mode

Turn on the calibration mode by pressing the "Calibrate" key while simultaneously turning on the power supply then continue to hold the "Calibrate" key for about 5 seconds until a beep is heard.

Make sure that the power supply is in "CV" mode. If the power supply is not in "CV" mode, an error occurs.

Move down a level to the voltage calibration mode for the +6V supply.

cal setup 1

The display shows the above message to indicate that the power supply is ready for the voltage calibration of +6V supply.

Select the first voltage calibration point for the +6V supply.

v lo +0.1111000 v

The display shows the first voltage calibration point for the +6V supply.

Read the DVM and change the first voltage value on the display to match

the measured voltage.

For example, if the DVM reading is 0.0860 V, adjust the voltage to 0.0860 V using the knob and resolution selection keys.

v lo +0.0860 v

Chapter 3 Calibration Procedures

General Calibration/Adjustment Procedure

Calibrate

Pressing the "Calibrate" key saves the change and selects the second

voltage calibration point for the +6V supply.

v hi +5.7000v

If the entered number is within an acceptable range, an "ENTERED" message appears for one second. The display now shows the second voltage calibration point for the +6V supply. If the entered number is not correct, an "INVALID DATA" message appears for one second and the display shows the first voltage calibration point again.

Read the DVM and change the second voltage value on the display to

match the measured voltage.

For example, if the DVM reads 5.9990 V, adjust the voltage to 5.9990 V using the knob and arrow keys.

v hi +5.9990v

Pressing the "Calibrate" key saves the new calibration constants for

the +6V output voltage and goes to the current calibration mode for the +6V supply.

cal setup 2

If the entered number is within an acceptable range, a "CALIBRATING" message appears for one second to indicate that the calibration is successful and that new calibration constants of "SETUP 1" are stored. Then, the display shows the above message to indicate that the power supply is ready for the current calibration for +6V supply.

If the entered number is not correct, an "INVALID DATA" message appears for one second and the display shows the second voltage calibration point again. If the calibration fails, a "CAL FAIL" message appears for one second and the display shows the "CAL SETUP 1" for the voltage calibration of the +6V supply again.

Chapter 3 Calibration Procedures

General Calibration/Adjustment Procedure

Connect an appropriate shunt (see Table 3-1 on page 42) across the +6V supply's output terminals, and connect a digital voltmeter across the shunt resistor for the current calibration.

Calibrate

Select the first current calibration point for the +6V supply.

i lo +0.100 a

The display shows the first current calibration point for the +6V supply.

Read the DVM and change the first current value on the display to

match the computed current (DVM reading

For example, if the computed value is 0.099 A, adjust the current to 0.099 A using the knob and arrow keys.

Notice that you should wait for the DVM reading to stabilize for accurate calibration.

¸ by shunt resistance).

i lo +0.099 a

Pressing the "Calibrate" key saves the change and selects the second

current calibration point for the +6V supply.

i hi +4.750 a

If the entered number is within an acceptable range, an "ENTERED" message appears for one second. The display now shows the second current calibration point for the +6V supply. If the entered number is not correct, an "INVALID DATA" message appears for one second and the display shows the first current calibration point again.

Chapter 3 Calibration Procedures

General Calibration/Adjustment Procedure

Read the DVM and change the second current value on the display to

match the computed current (DVM reading

For example, if the computed value is 4.999 A, adjust the current to 4.999 A using the knob and arrow keys.

Notice that you should wait for the DVM reading to stabilize for accurate calibration.

¸ by shunt resistance).

i hi +4.999 a

Calibrate

Pressing the "Calibrate" key saves the new calibration constants for

the +6V output current and goes to the voltage calibration mode for the +25V supply.

cal setup 3

If the entered number is within an acceptable range, a "CALIBRATING" message appears for one second to indicate that the calibration is successful and that new calibration constants of "SETUP 2" are stored. Then, the display shows the above message to indicate that the power supply is ready for the voltage calibration for +25V supply.

If the entered number is not correct, an "INVALID DATA" message appears for one second and the display shows the second voltage calibration point again. If the calibration fails, a "CAL FAIL" message appears for one second and the display shows the "CAL SETUP 2" for the current calibration of the +6V supply again.

Repeat steps (5) through (14) for the voltage and current calibration

of the +25V supply (replace +6V with +25V in all the text).

You can calibrate the output voltage and current of the +25V supply easily in the same manner. Notice that you should connect a shunt across (+) and (COM) terminals of the ±25V supply for the +25V supply current calibration.

Repeat steps (5) through (14) for the voltage and current calibration

of the -25V supply (replace +6V with -25V in all the text).

You can also calibrate the output voltage and current of the -25V supply easily in the same manner. Notice that you should connect a shunt across (-) and (COM) terminals of the ±25V supply for the -25V supply current calibration.

Chapter 3 Calibration Procedures

Aborting a Calibration in Progress

Sometimes it may be necessary to abort a calibration after the procedure has already been initiated. You can abort a calibration at any time by turning the power supply off from the front panel. When performing a calibration from the remote interface, you can abort a calibration by issuing a remote interface device clear message or by pressing the front-panel "Local" key.

Chapter 3 Calibration Procedures

Calibration Record for Agilent E3631A

Step Calibration Description

1 Unsecure the power supply (see page 62).

3 Move down menu to "CAL SETUP 1" (press "Calibrate" key). +6 supply

6 "CAL SETUP 2" now appears on the display (press "Calibrate" key). +6 supply

9 "CAL SETUP 3" now appears on the display (press "Calibrate" key). +25 supply

12 "CAL SETUP 4" now appears on the display (press "Calibrate" key). +25 supply

15 "CAL SETUP 5" now appears on the display (press "Calibrate" key). -25 supply

18 "CAL SETUP 6" now appears on the display (press "Calibrate" key). -25 supply

Turn on "CAL MODE"(simultaneously press "Calibrate" and "Power" keys) until a beep is heard.

"V LO 0.1000 V" appears on the display (change the display to match the DVM reading; then press ``Calibrate'' key).

"V HI +5.7000 V" appears on the display (change the display to match the DVM reading; then press "Calibrate" key).

"I LO 0.100 A" appears on the display (change the display to match the computed current through 0.19 resistor; then press "Calibrate" key).

"I HI +4.750 A" appears on the display (change the display to match the computed current through 0.19 resistor; then press "Calibrate" key).

"V LO 0.5000 V" appears on the display (change the display to match the DVM reading; then press "Calibrate" key).

"V HI +24.750 V" appears on the display (change the display to match the DVM reading; then press ``Calibrate'' key).

"I LO 0.100 A" appears on the display (change the display to match the computed current through 0.19 resistor; then press "Calibrate" key).

"I HI +0.950 A" appears on the display (change the display to match the computed current through 0.19 resistor; then press "Calibrate" key).

"V LO -0.5000 V" appears on the display (change the display to match the DVM reading; then press "Calibrate" key).

"V HI -24.750 V" appears on the display (change the display to match the DVM reading; then press "Calibrate" key).

"I LO 0.100 A" appears on the display (change the display to match the computed current through 0.19 resistor; then press "Calibrate" key).

"I HI +0.950 A" appears on the display (change the display to match the computed current through 0.19 resistor; then press "Calibrate" key).

Measurement

Mode (DVM)

Supply

being

Adjusted

V +6 supply

A +6 supply

V +25 supply

A +25 supply

V -25 supply

A -25 supply

Chapter 3 Calibration Procedures

Error Messages

The following tables are abbreviated lists of error messages for the E3631A. The errors listed are the most likely errors to be encountered during calibration and adjustment. A more complete list of error messages and descriptions is contained in chapter 5 of the E3631A User's Guide.

System Error Messages

Error Error Message

-330 Self-test failed

-350 Too many errors 501 Isolator UART framing error 502 Isolator UART overrun error 511 RS-232 framing error 512 RS-232 overrun error 513 RS-232 parity error 514 Command allowed only with RS-232 521 Input buffer overflow 522 Output buffer overflow 550 Command not allowed in local 800 P25V and N25V coupled by track system 801 P25V and N25V coupled by trigger subsystem

Self-Test Error Messages

Error Error Message

601 Front panel does not respond 602 RAM read/write failed 603 A/D sync stuck 604 A/D slope convergence failed 605 Cannot calibrate rundown gain 606 Rundown gain out of range 607 Rundown too noisy 608 Serial configuration readback failed 624 Unable to sense line frequency 625 I/O processor does not respond 626 I/O processor failed self-test 630 Fan test failed 631 System DAC test failed 632 P6V hardware test failed 633 P25V hardware test failed 634 N25V hardware test failed

Chapter 3 Calibration Procedures

Error Messages

Calibration Error Messages

Error Error Message

701 Cal security disabled by jumper 702 Cal secured 703 Invalid secure code 704 Secure code too long 708 Cal output disabled 711 Cal sequence interrupted 712 Bad DAC cal data 713 Bad readback cal data 740 Cal checksum failed, secure state 741 Cal checksum failed, string data 742 Cal checksum failed, store/recall data in location 1 743 Cal checksum failed, store/recall data in location 2 744 Cal checksum failed, store/recall data in location 3 745 Cal checksum failed, DAC cal constants 746 Cal checksum failed, readback cal constants 747 Cal checksum failed, GPIB address 748 Cal checksum failed, internal data

Chapter 3 Calibration Procedures

Calibration Program

This section contains an Agilent BASIC program for calibration over the GPIB interface. This program makes software adjustments to the E3631A power supply using a current shunt and a digital mutimeter which is connected to the controller. In this program a 0.01 ohm current shunt is used. Be sure to change the value of the variable "Current_shunt" to the value of the current shunt used and the GPIB address for the power supply and the digital voltmeter.

10 ! 20 ! This program makes software adjustments to the E3631A on the GPIB bus 30 ! using an Agilent 34401A and a current shunt. In the program a 0.01 ohm 40 ! current shunt is used to measure current. Be sure to change the value of 50 ! the variable ’Current_shunt’ to the value of the current shunt used. 60 ! 70 CLEAR SCREEN 80 DIM Cal_msg$[40], Sec_code$[40],Sec_code$[10] 90 REAL Dmm_rdg, Current_shunt 100 Current_shunt=.01 ! Current Shunt value in Ohms 110 Sec_Code$="HP003631" ! Assign the security code. 120 ASSIGN @Dmm TO 722 ! Assign address 22 to the Dmm. 130 ASSIGN @Psup TO 705 ! Assign address 5 to the power supply. 140 CLEAR 7 ! Clear GPIB, Dmm and Power Supply. 150 OUTPUT @Psup;"*CLS" ! Clear power supply errors. 160 OUTPUT @Dmm;"*RST" ! Clear Dmm. 170 OUTPUT @Psup;"*RST" ! Reset power supply. 180 OUTPUT @ Psup;"CAL:STR?" ! Read the calibration message. 190 ENTER @Psup;Cal_msg$ 200 PRINT TABXY(5,2),"Calibration message of Power Supply is: ";Cal_msg$ 210 ! 220 ! Set the Calibration security to off, and check to be sure 230 ! it is off. If not successful, print message to screen and end. 240 ! 250 OUTPUT @Psup;"CAL:SEC:STAT OFF, ";Sec_code$ 260 OUTPUT @Psup;"CAL:SEC:STAT?" 270 ENTER @Psup;A 280 IF A=1 THEN 290 PRINT TABXY(5,5),"****** Unable to Unsecure the Power supply ******" 300 GOTO 1430 310 END IF 320 ! 330 ! Perform the voltage calibration by stepping through one 340 ! power supply at a time. Alert the operator to hook up the 350 ! connection before calibrating. 360 ! 370 FOR I=1 TO 3 380 OUTPUT @Psup;"INST:NSEL ";I !Select the output to be calibrated. 390 ! Alert operator to connect lead

Chapter 3 Calibration Procedures

Calibration Program

...continued

400 PRINT TABXY(10,10),"*************************************************" 410 PRINT TABXY(10,11)," Using the annunciator, note the output selected." 420 PRINT TABXY(10,12)," Connect the selected output to the DMM. Observe" 430 PRINT TABXY(10,13)," Polarity." 440 PRINT TABXY(10,14),"*************************************************" 450 PRINT TABXY(10,15),"Press ’C’ to continue, or ’E’ to Exist, then" 460 PRINT TABXY(10,16),"press ’Enter’" 470 Ch$="C" 480 INPUT Ch$ 490 IF Ch$="E" OR Ch$="e" THEN GOTO 1420 500 OUTPUT @Psup;"OUTP ON" ! Turn on Power supply output. 510 CLEAR SCREEN 520 OUTPUT @Psup;"CAL:VOLT:LEVel MIN" ! Set output to minimum calibration 530 ! value 540 WAIT 1 ! Allow output to settle. 550 OUTPUT @Dmm;"MEAS:VOLT:DC? " ! Measure output with Dmm. 560 ENTER @Dmm;Dmm_rdg ! Sotre in variable Dmm_rdg. 570 PRINT Dmm_rdg 580 OUTPUT @Psup;"CAL:VOLT:DATA ";Dmm_rdg ! Send stored value to power 590 ! supply 600 OUTPUT @Psup;"CAL:VOLT:LEVel MAX" ! Set output to maximum cal value. 610 WAIT 1 ! Allow output to settle. 620 OUTPUT @Dmm;"MEAS:VOLT:DC?" ! Measure output with Dmm. 630 ENTER @Dmm;Dmm_rdg ! Store in variable Dmm_rdg. 640 PRINT Dmm_rdg 650 OUTPUT @Psup;"CAL:VOLT:DATA ";Dmm_rdg ! Send stored value to power 660 ! supply 670 OUTPUT @Psup;"OUTP OFF" 680 OUTPUT @Psup;"SYST:ERR?" 690 ENTER @Psup;Error$ 700 ! 710 ! Check to see if there is an error. If there is an error, 720 ! display the error and exit the program. 730 ! 740 IF Error$="+0,""No error""" THEN 750 PRINT "Voltage calibration complated for Power Supply ";I 760 ELSE 770 PRINT "ERROR:";Error$;" Power Supply ";I;" Voltage not Calibrated" 780 GOTO 1420 790 END IF 800 NEXT I 810 PRINT TABXY(10,5),"VOLTAGE CALIBRATION COMPLETE" 820 PRINT TABXY(10,7),"BEGIN CURRENT CALIBRATION" 830 ! 840 ! Perform the CURRENT calibration by stepping through one 850 ! power supply at a time. Alert the operator to hook up the 860 ! connection before calibrating. 870 ! 880 FOR I=1 TO 3 890 OUTPUT @Psup;"INST:NSEL ";I !Select the output to be calibrated. 900 ! Alert operator to connect lead

Chapter 3 Calibration Procedures

Calibration Program

...continued

910 PRINT TABXY(10,9),"***************************************************" 920 PRINT TABXY(10,10)," Connect a CURRENT SHUNT to the Dmm for measuring" 930 PRINT TABXY(59,10)," current." 940 PRINT TABXY(10,11)," Using the annunciator, note the output selected." 950 PRINT TABXY(10,12)," Connect the selected output to the shunt. Observe" 960 PRINT TABXY(60,12)," Polarity" 970 PRINT TABXY(10,13),"**************************************************" 980 PRINT TABXY(10,15),"Press ’C’to continue, or ’E’ to Exit, then" 990 PRINT TABXY(10,16),"press ’Enter’" 1000 Ch$="C" 1010 INPUT Ch$ 1020 IF Ch$="E" OR Ch$="e" THEN GOTO 1420 1030 OUTPUT @Psup;"OUTP ON" ! Turn on Power supply output. 1040 CLEAR SCREEN 1050 OUTPUT @Psup;"CAL:CURR:LEVel MIN" ! Set output to minimum cal value. 1060 WAIT 1 ! Allow output to settle. 1070 OUTPUT @Dmm;"MEAS:VOLT:DC? " ! Measure output with Dmm. 1080 ENTER @Dmm;Dmm_rdg ! Store in variable Dmm_rdg. 1090 Dmm_rdg=Dmm_rdg/Current_shunt ! Scale reading to amps. 1100 IF I=3 THEN DMM_rdg=-DMM_rdg ! For -25V, Current is positive 1110 PRINT Dmm_rdg 1120 OUTPUT @Psup;"CAL:CURR:DATA ";Dmm_rdg ! Send stored value to power 1130 ! supply 1140 OUTPUT @Psup;"CAL:CURR:LEVel MAX" ! Set output to maximum cal value. 1150 WAIT 1 ! Allow output to settle. 1160 OUTPUT @Dmm;"MEAS:VOLT:DC? " ! Measure output with Dmm. 1170 ENTER @Dmm;Dmm_rdg ! Store in variable Dmm_rdg. 1180 Dmm_rdg=Dmm_rdg/Current_shunt ! Scale reading to amps. 1190 IF I=3 THEN DMM_rdg=-DMM_rdg ! For -25V, Current is positive 1200 PRINT Dmm_rdg 1210 OUTPUT @Psup;"CAL:CURR:DATA ";Dmm_rdg ! Send stored value to power 1220 ! supply. 1230 OUTPUT @Psup;"OUTP OFF" ! Turn off Power supply output. 1240 OUTPUT @Psup;"SYST:ERR?" 1250 ENTER @Psup;Error$ 1260 ! 1270 ! Check to see if there is an error. If there is an error, 1280 ! display the error and exit the program. 1290 ! 1300 IF Error$="+0, No error""" THEN 1310 PRINT "Current calibration completed for Power Supply ";I 1320 ELSE 1330 PRINT "ERROR:";Error$;" Power Supply ";I;" Current not Calibrated" 1340 GOTO 1420 1350 END IF 1360 NEXT I 1370 CLEAR SCREEN 1380 PRINT TABXY(10,5),"CURRENT CALIBRATION COMPLETE" 1390 ! Create a time stamp and output to power supply 1400 Cal_msg$_"Last Calibrated "$DATE$(TIMEDATE)&" "&TIME$(TIMEDATE) 1410 OUTPUT @Psup;"CAL:STR """;Cal_msg$;"""" 1420 OUTPUT @Psup;"CAL:SEC:STAT ON, ";Sec_code$ 1430 END

Chapter 3 Calibration Procedures

Calibration Program

Theory of Operation

This chapter provides block diagram level descriptions of the power supply. The descriptions provide a basic understanding of circuit operation and are intended as an aid in troubleshooting. It is assumed in the following discussions that you are familiar with the operating and programming instructions presented in the E3631A User's Guide. Subjects covered include the following:

• Block Diagram Overview, page 81

• AC Input and Bias Supplies, page 83

• Floating Logic, page 84

• D-to-A Converter, page 86

• A-to-D Converter, page 87

• Power Mesh and Control, page 88

• Earth-Referenced Logic, page 90

• Front Panel, page 90

Chapter 4 Theory of Operation

Block Diagram Overview

This discussion pertains to the block diagram on the next page. The power supply's circuitry is divided into two major blocks: the floating circuitry and the ground referenced circuitry. All power mesh and control circuits, display circuit, and digital circuits are contained in the floating circuitry. This circuitry also contains the power supply's main controller. The ground referenced circuitry provides the interface between the user and the power supply.

The floating circuitry can be viewed in four pieces; the DAC system, the digital logic section (floating logic), the power mesh and control section (+6V and ±25V power circuits), and the front panel (display and keyboard) section.

The floating logic receives digital signals from the earth-referenced logic and the DAC converts them to analog signals which are sent to the power control circuits in order to program the power supply's output voltage and current. The power supply can also be commanded to send measurement and status data back to the remote interface controller and/or the VFD (vacuum fluorescent display) display on the front panel. The data is processed and sent back via the floating logic and earth-referenced logic.

The power mesh and control circuits contains voltage and current control circuits which allows the power supply to operate in either the constant voltage (CV) or constant current (CC) mode. The control circuits compare the power supply's output voltage or current with the programmed value and generates a control signal which varies the conduction of the series pass transistor to raise or lower the output as required.

The front panel circuits consist of VFD control, display high voltage drivers, and keyboard scanning. Communication between the front panel and floating logic circuits is accomplished through a 4-wire bi-directional serial interface.

The ground referenced circuitry uses a controller configured as a slave to the main controller. This controller establishes external I/O communication with the main controller through a bi-directional, optically isolated, serial communications link. The earth referenced controller controls low-level GPIB (IEEE-488) and RS-232 interface operation.

Separate reference and bias supplies are provided for the floating and ground reference circuitry. The front panel operates from the floating circuitry with its logic common different from the main controller logic common.

Chapter 4 Theory of Operation

Block Diagram Overview

Block Diagram

FLOATING CIRCUITRY

EARTH REFERENCED CIRCUITRY

Chapter 4 Theory of Operation

AC Input and Bias Supplies

Referring to the schematic shown on page 127, the ac mains are connected by a fused power module. This module incorporates the functions of mains connection, fusing, and line voltage selection (100/115/230 Vac). The line voltage selection function of the module selects which primary winding of power transformer T1 is energized. The transformer secondary windings are connected to the main pc board through connectors.

The bias supplies are consists of four sections; ±15 Vdc for the +6V power circuits; ±15 Vdc, +5 Vdc and -5.1 Vdc for the ±25V power circuits and floating logic; ±16.4 Vdc for the display; and +5 Vdc for the earth referenced logic. Power-on reset signals are provided by the +5 Vdc supply of the floating logic.

The ±15 Vdc for the +6V power circuits are produced by rectifiers CR15 and CR16, filter capacitors C43 and C44, and voltage regulators U24 and U25 on the bottom board. These supplies provide bias voltages for the +6V power circuits.

The ±16.4 Vdc for the display circuits are produced by rectifier CR20, filter capacitors C44 and C45, and voltage regulators U24 and U25 on the top board. A separate winding of T1 provides a center tapped 6 Vrms filament supply for the display.

The ±15 Vdc for the ±25V power circuits are derived from ±16.4 Vdc by diodes CR15 through CR18 on the top board. These supplies provide bias voltages for the ±25V power circuits.

The floating +5 Vdc and -5.1 Vdc supplies are produced from ±16.4 Vdc supplies. VR2 on the top board forms a clamp circuit to provide over voltage protection in the event of a regulator failure. The ADC REF signal is derived from +15 Vdc supply and the TURN_ON RESET signal is derived from +5 Vdc supply. The FAN FAIL signal is asserted when the fan current through R73 on the top board is not detected. The TURN_ON RESET signal holds the main controller and other logic in a reset state until after the +5 Vdc logic power is fully operational. This signal is generally active only following application of line power to the instrument.

The +5V dc earth referenced supply is produced by rectifier CR3, filter capacitor C15, and regulator U11 on the bottom board. The GPIB (IEEE-488) and RS-232 computer interfaces are powered from this supply.

Chapter 4 Theory of Operation

Floating Logic

Referring to the schematic shown on page 128, the floating common logic controls operation of the entire instrument. All output functions and bus command interpretation is performed in the main controller U17. The front panel and the earth referenced logic operate as slaves to U17. The floating common logic is comprised of the main controller U17, custom gate array U16, the program ROM U14, RAM U15, calibration EEPROM U18, and the 12 MHz clock oscillator Y1 on the top board . Non-volatile EEPROM U18 stores calibration constants, calibration secure code, and calibration count. Poweron reset is provided to the main controller by the voltage regulator U1 on the top board.

The main controller U17 is a 16-bit micro controller. It controls such features as receive and transmit serial port, timer/counter ports, an 8-bit pulse width modulated DAC port, and selectable input 10-bit successive approximation ato-d convert ports. A conventional address/data bus is used to transfer data between the main controller and external ROM and RAM. When the address latch enable (ALE) signal goes high, address data is present on the address/ data bus. ASIC U16 latches the address data and decodes the correct chip enable (low true) for external ROM and RAM accesses and for read/write accesses to the internal registers of U16. The system memory map is shown below.

0000H - 1FF7HU15 8k x 8 RAM 1FF8H - 1FFFHU16 Gate Array

- FFFFHU14 Program ROM

2000

Prog r am RO M U 14 co nta i n s fou r 64 k x 8 da t a ban k s of dat a . B a n k s are se lec t e d by controlling A16 and A17 ROM address bits directly from the main controller port bits.

Custom gate array U16 performs address latching and memory map decoding functions as discussed above. In addition, U16 contains a variety of internal read/write registers. The read (XRD) and write (XWR) signals transfer data out of and into U16 when it is addressed. There are four internal registers in U16: an internal configuration register, an 8 bit counter register, a serial transmit/ receive register, and an internal status register.

Th e c o u nt e r re g i st e r is u s e d to ca p t ur e th e A D C sl o p e cou n t at t he COM P i n p ut . The COMP input functions as both a clocked comparator and the slope counter input for the ADC. In both cases the counter register captures the lower 8 bits of a 24-bit counter. The upper 16 bits of the count are captured by the SYNC input to U17.

Chapter 4 Theory of Operation

Floating Logic

The serial register is used to send and receive serial data bytes from the main controller to the DAC system, or to communicate with the front panel controller. The serial register is multiplexed to these two circuits. The transmission rate is selected to 1.5 M bits/second for the DAC system and 93.75 k bits/second for communication with the front panel controller. The general serial interface is a 3-bit interface as shown below.

U18 Internal Signal Configuration Signals Front Panel Signals

Serial Clock Data OUT (send) Data IN (receive)

SERCK SERDAT SERRBK

XFPSK

FPDI

FPDO

Serial data is received simultaneously as serial data is clocked out. Front panel data is exchanged in both directions whenever a byte is sent from U16 on the top board. The input data of DAC is strobed to outputs by U17 signal SERSTB. Interrupts from the front panel are detected by U16 and signaled to the CHINT. The main controller FPINT signals the front panel controller that U16 has data to send.

The power supply's calibration correction data are stored in a 128 x 16 bit nonvolatile electrically erasable ROM U18 on the top board. This non-volatile ROM read/write data is accessed by a 4-bit serial protocol controlled by U17.

The main controller has an on-chip 10-bit successive approximation ADC. The FLASH input is used to sample the residual charge on the main integrating ADC output of U8 on the top board.

Port bits are also configured to measure the input power line frequency (LSENSE). Frequencies from 55 Hz to 66 Hz are measured as 60 Hz. All other line input frequencies are assumed to be 50 Hz.

The main controller communicates with the earth referenced controller U10 on the bottom board through an optically isolated (U1 and U2 on the bottom board) asynchronous serial link. Data is sent in an 11-bit frame at a rate of 187.5 k bits/ second. When the RS-232 interface is selected, data is sent across the isolated link at 93.75 k bits/second. The 11-bit data frame is configured for one start bit, eight data bits, one control bit, and one stop bit.

Chapter 4 Theory of Operation

D-to-A Converter

Referring to the schematic shown on page 129, all reference voltages of power circuits are derived from the inte rnal voltage reference of system DAC U 12 on the top board. The system DAC track/hold amplifier outputs are used to provide controllable reference voltages to three power circuits. The system DAC is programmed and responds to the main controller via internal 3-wire serial data bus SERCLK, SERRBK, and SERSTB. The system DAC is mutiplexed to 6 track/hold amplifiers through U13 on the top board. Each track/hold amplifier is refreshed approximately every 13 msec to maintain its output setting. Changes to track/hold amplifier outputs are accomplished by dwelling on that position for an extended period.

Chapter 4 Theory of Operation

A-to-D Converter

Referring to the schematic shown on page 129, the analog-to-digital converter (ADC) is used to change dc voltages into digital information. The circuitry consists of an integrator amplifier (U6 and U8), current steering switch U5, resistors (R5, R4, R15 and R16), voltage reference (U3A and U3B), ADC controller U16, and residue ADC U17 on the top board.

The ADC method used by the Agilent E3631A is called multislope III. Multislope III is a charge balancing continuously integrating analog-to-digital converter. The input voltage continuously forces charge onto the integrator capacitors C18 and C19 through R15 on the top board.

Switch U5 steers fixed positive or negative reference currents onto the integrator capacitors to cancel, or balance the accumulated input charge. The level shifted (R19 and R20 on the top board) output of the integrator is checked every 2.66 mA by the U1 6 CO M P input. Lo g ic state mac h i n es in U16 contr o l the U5 current steering to continuously seek an approximate 2.5 V level on the integrator amplifier output, FLASH. If the ADC input voltage ADC REF is between ±15 V, the integrator output (FLASH) will remain within the 0 V to 5 V range of the U17 on-chip ADC. An input greater than +15 V may cause the integrator output in U8 at pin 6 (U8-6) to saturate at about -15 V. An input less than -15 V may cause U8 to saturate with an output of about +15 V. The U17 ADC input (FLASH) is clamped to 0 V or 5 V by R21 and CR3 to protect U17.

The integrator amplifier is formed by U6 and U8. Resistors R10 and R11 affect the amplifier stability. Amplifier oscillation may occur if their values are incorrect. Amplifier U6 improves the offset voltage characteristics of integrator amplifier U8 on the top board.

Each analog-to-digital conversion occurs continuously. The ADC starts by clearing the integrator slope count in U16. At the end of the integration period, the slope count is latched. The slope count provides the most significant bits of the input voltage conve rsion. The lea st significant bits are converted by the on-chip ADC of U17.

Chapter 4 Theory of Operation

Power Mesh and Control

Refer to the schematics shown on page 130 and page 131.

For the ±25V power mesh and control circuit, a preregulator is added ahead of the series pass transistor to minimize the power dissipated in the series pass transistor by controlling the dc level across the input filter capacitor, depending on the output voltage.

To achieve this, tap switching is accomplished by a TRIAC and one bridge diode and the TRIAC control circuit in each power circuit; Q10 and CR29 on the top board for +25V power circuit, Q3 and CR7 on the top board for -25V power circuit. By turning on or off the TRIAC, these circuits allow the input capacitors (C54, C55, and C56 for +25V power circuit and C34, C35, and C36 for -25V power circuit) to charge to one of two discrete voltage levels, depending on the output voltage required. When the TRIAC is not fired, the bridge diode conducts and the low voltage of two discrete voltage levels is developed across the input filter capacitors.

The TRIAC control circuit determines whether TRIAC is to be fired by monitoring the output voltage and comparing this value against internally derived reference levels.

The series pass transistor is part of a feedback loop which consists of the driver and the Constant Voltage/Constant Current error amplifier. The feedback loop provides "fine and fast" regulation of the output while the preregulator feedback loop handles large, relatively slow, regulation demands.

The series pass transistor is made to alter its conduction to maintain a constant output voltage or current. The voltage developed across the current sampling resistors is the input to the constant current error amplifier. The constant voltage error amplifier obtains its input by sampling the output voltage of the supply. Any changes in output voltage or current are detected and amplified by the constant voltage or constant current error circuit and applied to the series pass transistor in the correct phase and amplitude to counteract the change in output voltage or current.

Chapter 4 Theory of Operation

Power Mesh and Control

Two error amplifiers are included in a CV/CC supply, one for controlling output voltage, the other for controlling output current. Since the constant voltage amplifier tends to achieve zero output impedance and alters the output current whenever the load resistance changes, while the constant current amplifier causes the output impedance to be infinite and changes the output voltage in response to any load resistance change, it is obvious that the two amplifiers can not operate simultaneously. For any given value of load resistance, the power supply must act either as a constant voltage source or as a constant current source - it can not be both; transfer between these two modes is accomplished at a value of load resistance equal to the ratio of the output voltage control setting to the output current control setting.

Full protection against any overload condition is inherent in the Constant Voltage/Constant Current design principle since there is not any load condition that can cause an output which lies outside the operating region. For either constant voltage or constant current operation, the proper choice of front panel voltage and current limit settings insures optimum protection for the load device as well as full protection for the power supply.

The diodes connected across the output terminals in reverse polarity protect the output electrolytic capacitor and the series pass transistors from the effects of a reverse voltage applied across the output terminals.

The +6V power mesh and control circuits are similar to those of the ±25V power ci rcui ts except t hat the th e T RIAC prere gula tor i s not use d. T he ac i nput , after passing through power transformer, is rectified and filtered. By feedback action, the series pass transistor alters its conduction to keep the regulated dc output voltage constant.

The +6V and the ±25V power mesh and control circuits are isolated from each other and the two outputs of the ±25V power mesh and control circuit share a common output terminal.

Chapter 4 Theory of Operation

Earth-Referenced Logic

Referring to the schematic shown on page 132, the earth referenced logic circuits schematic provides all rear panel input/output capability. Microprocessor U10 on the bottom board handles GPIB (IEEE-488) control through bus interface chip U8 and bus receiver/driver chips U6 and U7 on the bottom board. The RS-232 interface is also controlled through microprocessor U10. RS-232 transceiver chip U12 on the bottom board provides the required level shifting to approximate ±9 volt logic levels through on-chip charge-pump power supplies using C11 and C12 on the bottom board. Communication between the earth referenced logic interface circuits and the floating logic is accomplished through an optically-isolated bi-directional serial interface. Isolator U2 on the bottom board couples data from U10 to processor U17 on the top board. Isolator U1 on the bottom board couples data from U17 on the top board to microprocessor U10 on the bottom board.

Front Panel

Re fer rin g to the sche mati c shown o n pa ge 13 3, th e front panel cir cuit s consi st of vacuum fluorescent display control, display high voltage drivers, and keyboard scanning. Communication between the front panel and floating logic circuits is accomplished through a 4-wire bi-directional serial interface. The main controller U17 can cause a hardware reset to front-panel controller by signal IGFPRES. The front panel logic operates from -11.4 volts (logic 1) and -

16.4 volts (logic 0). The front panel logic high supply (-11.4 volts) is produced by the -16.4 volts bias supply and the voltage regulator U2 on the front panel board. The four serial communication signals are level shifted by the comparator U8 from the floating logic 0 V to 5 V levels to the -16.4 V to -11.4 V levels present on the front panel assembly. U6 acts as the serial shift register interface for the front-panel controller U7 on the front panel board.

Display anode and grid voltages are +16.4 volts for an "on" segment and -16.4 volts for an "off" segment. The -10.2 V cathode bias for the display is provided by filament winding center tap bias circuit VR3, R43, and C32 on the top board. Keyboard scanning is accomplished through a conventional scanned rowcolumn key matrix. Keys are scanned by outputing data at front-panel controller U7 port pins P0.0 through P0.3 to poll each key column for a key press. Column read-back data are read by the microprocessor at port pins P1.0 through P1.3 for decoding and communication to the floating logic circuits.

Service

This chapter discusses the procedures involved for returning a failed power supply to Agilent Technologies for service or repair. Subjects covered include the following:

• Operating Checklist, page 93

• Types of Service Available, page 94

• Repacking for Shipment, page 95

• Electrostatic Discharge (ESD) Precautions, page 96

• Surface Mount Repair, page 96

• To Replace the Power-Line Fuse, page 96

• Troubleshooting Hints, page 97

• Self-Test Procedures, page 99

Chapter 5 Service

Operating Checklist

Before returning your power supply to Agilent Technologies for service or repair check the following items:

Is the Power Supply Inoperative?

Verify that the ac power cord is connected to the power supply.

Verify that the front-panel power switch is depressed.

Verify that the power-line fuse is installed:

Use the 2.5 AT, 250 V fuse for 100 or 115 Vac operation. Use the 2 AT, 250 V fuse for 230 Vac operation.

Verify the power-line voltage setting.

See "To prepare the power supply for use" page 23.

Does the Power Supply Fail Self-Test?

Verify that the correct power-line voltage is selected.

See "To prepare the power supply for use" page 23.

Remove all load connections to the power supply.

Ensure that all terminal connections are removed while the self-test is performed.

Chapter 5 Service

Types of Service Available

If your power supply fails within three years of original purchase, Agilent Technologies will repair or replace it free of charge. If your unit fails after your three year warranty expires, Agilent will repair or replace it as a very competitive price. Agilent will make the decision locally whether to repair or replace your unit.

Standard Repair Service (worldwide)

Contact your nearest Agilent Technologies Service Center. They will arrange to have your power supply repaired or replaced.

Express Exchange (U.S.A. only)

You can receive a replacement Agilent E3631A via overnight shipment for low downtime.

Call 1-800-258-5165 and ask for "Express Exchange."

• You will be asked for your shipping address and a credit card number to guarantee return of your failed power supply.

• If you do not return your failed power supply within 45 days, your credit card will be billed for a new Agilent E3631A.

• If you choose not to supply a credit card number, you will be asked to send your failed unit to a designated Agilent Service Center. After the failed unit is received, Agilent will send your replacement unit.

Agilent Technologies will immediately send a replacement Agilent E3631A to

you via overnight shipment.

• The replacement unit will have a different serial number than your failed unit.

• If you can not accept a new serial number for the replacement unit, use the Standard Repair Service option described above.

• If your failed unit was "in-warranty,'' your replacement unit continues the original three year warranty period. You will not be billed for the replacement unit as long as the failed unit is received by Agilent Technologies.

• If your three year warranty has expired, Agilent will bill you for the Agile nt E3631A exchange price - less than a new unit price. Agilent warrants exchange units against defects for 90 days.

Chapter 5 Service

Repacking for Shipment

For the Express Exchange Service described on the previous page, return your failed Agilent E3631A to the designated Agilent Service Center using the shipping carton of the exchange unit. A shipping label will be supplied. Agilent will notify you when your failed unit has been received.

If the instrument is to be shipped to Agilent Technologies for service or repair, be sure to:

• Attach a tag to the power supply identifying the owner and indicating the required service or repair. Include the instrument model number and full serial number.

• Place the power supply in its original container with appropriate packaging material.

• Secure the container with strong tape or metal bands.

If the original shipping container is not available, place your unit in a container which will ensure at least 4 inches of compressible packaging material around all sides for the power supply. Use static-free packaging materials to avoid additional damage to your unit.

Agilent Technologies suggests that you always insure shipments.

Chapter 5 Service

Electrostatic Discharge (ESD) Precautions

Almost all electrical components can be damaged by electrostatic discharge (ESD) during handling. Component damage can occur at electrostatic discharge voltages as low as 50 volts.

The following guidelines will help prevent ESD damage when serving the power supply or any electronic device.

• Disassemble instruments only in a static-free work area.

• Use a conductive work area to dissipate static charge.

• Use a conductive wrist strap to dissipate static charge accumulation.

• Minimize handling.

• Keep replacement parts in original static-free packaging.

• Remove all plastic, styrofoam, vinyl, paper, and other static-generating materials from the immediate work area.

•Use only anti-static solder suckers.

Surface Mount Repair

Surface mount components should only be removed using soldering irons or disordering stations expressly designed for surface mount components. Use

of conventional solder removal equipment will almost always result in permanent damage to the printed circuit board and will void your Agilent Technologies factory warranty.

To Replace the Power-Line Fuse

The power-line fuse is located within the power supply's fuse-holder assembly on the rear panel (see page 24). For 100 or 115 Vac operation, you must use a

2.5 AT slow-blo w fuse (Agile nt part numbe r 2110 -0913) . For 230 Va c opera tion,

you must use a 2 AT slow-blow fuse (Agilent part number 2110-0587).

Chapter 5 Service

Troubleshooting Hints

This section provides a brief check list of common failures. Before troubleshooting or repairing the power supply, make sure that the failure is in the instrument rather than any external connections. Also make sure that the instrument is accurately calibrated. The power supply's circuits allow troubleshooting and repair with basic equipment such as a digit multimeter and a 100 MHz oscilloscope.

Unit is Inoperative

Verify that the ac power cord is connected to the power supply.

Verify that the front-panel power switch is depressed.

Verify that the power-line fuse is installed:

Use the 2.5 AT, 250 V fuse for 100 or 115 Vac operation.. Use the 2 AT, 250 V fuse for 230 Vac operation..

Verify the power-line voltage setting.

See "To prepare the power supply for use" page 23.

Unit Reports Errors 740 to 748

These errors may be produced if you accidentally turn off power the unit during a calibration or while changing a non-volatile state of the instrument. Recalibration or resetting the state should clear the error. If the error persists, a hardware failure may have occurred.

Unit Fails Self-Test

Verify that the correct power-line voltage setting is selected. Also, ensure that all terminal connections are removed while the self-test is performed. Failure of the DAC U12 on the top board will cause many self-test failures.

Chapter 5 Service

Troubleshooting Hints

Bias Supplies Problems

Check that the input to the voltage regulators of the bias supplies is at least 1 V greater than their output.

Circuit failures can cause heavy loads of the bias supplies which may pull down the regulator output voltages.

Check the voltages of bias supplies as tabulated below.

Table 5-1. Bias Supplies Voltages

Bias Supply Minimum Maximum Check At

+5V Floating

-5.1V Floating +15V Floating (±25V supplies)

-15V Floating (±25V supplies) +15 Floating (+6V supplies)

-15 Floating (+6V supplies) +5V Ground Ref.

Some circuits produce their own local bias supplies from the main bias supplies. Be sure to check that these local bias supplies are active. In particular, the ADC (analog-to-digital converter), ac input, and front panel sections have local bias supplies. Always check that the power supplies are free of ac oscillations using an oscilloscope. Failure of bias supplies will cause many selftest failures.

4.75 V

-4.75 V

14.25 V

-14.25 V

14.25 V

-14.25 V

4.75 V

5.25 V

-5.25 V

15.75 V

-15.75 V

15.75 V

-15.75

5.25 V

U1 pin 2 (on the top Board) Anode of VR4 (on the top Board) Cathode of CR16 (on the top Board) Anode of CR18 (on the top Board) U25 pin 2 (on the bottom Board) U24 pin 3 (on the bottom Board) U11 pin 3 (on the bottom Board)

Chapter 5 Service

Self-Test Procedures

Power-On Self-Test

Each time the power supply is powered on, a set of self-tests are performed. These tests check that the minimum set of logic and measurement hardware are functioning properly. The power-on self-test performs checks 601 through 604 and 624 through 634.

Complete Self-Test

Ho ld any fro n t panel k e y except t he "Error ' ' key fo r mo re t han 5 se con ds w hile turning on the power to perform a complete self-test. The power supply beeps when the test starts. The tests are performed in the order shown below.

601

602

603

604

Front Panel Does not respond The main controller U17 on the top board attempts to establish serial communications with the front panel controller U7 on the front panel board. During this test, U7 turns on all display segments. Communication must function in both directions for this test to pass. If this error is detected during power-on self-test, the power supply will beep twice. This error is only readable from the remote interface.

RAM read/write failed This test writes and reads a 55 board pattern to each address of ram U15 on the top board. Any incorrect

readback will cause a test failure. This error is only readable from the remote interface.

A/D sync stuck The main controller issues an A/D sync pulse to U17 and U16 on the top board to latch the value in the ADC slope counters. A failure is detected when a sync interrupt is not recognized and subsequent time-out occurs.

A/D slope convergence failed The input amplifier is configured to the measure zero (MZ) state in the 10 V range. This test checks whether the ADC integrator produces nominally the same number of positive and negative slope decisions (±10%) during a 20 ms interval.

and AAh checker

HP e3631 schematic

Specifications and Main Features

Frequently Asked Questions

User Manual

The Front Panel at a Glance

Front-Panel Voltage and Current Settings

Display Annunciators

The Rear Panel at a Glance

In This Book

Contents

Specifications

Performance Specifications

Supplemental Characteristics

Quick Start

To prepare the power supply for use

To check the rated voltages of the power supply

To check the rated currents of the power supply

To use the power supply in constant voltage mode

To use the power supply in constant current mode

To use the power supply in track mode

To store and recall the instrument state

To rack mount the power supply

Calibration Procedures

Agilent Technologies Calibration Services

Calibration Interval

Automating Calibration Procedures

Recommended Test Equipment

Test Considerations

Performance Verification Tests

Performance Verification Tests

Self-Test

Measurement Techniques

Setup for Most Tests

Current-Monitoring Resistor

Programming

Voltage and Current Values

Constant Voltage (CV) Verifications

Constant Voltage Test Setup

Voltage Programming and Readback Accuracy

CV Load Regulation

CV Line Regulation

Normal Mode Voltage Noise (CV Ripple and Noise)

Common Mode Current Noise

Load Transient Response Time

Constant Current (CC) Verifications

Constant Current Test Setup

Current Programming and Readback Accuracy

CC Load Regulation

CC Line Regulation

Normal Mode Current Noise (CC Ripple and Noise)

Performance Test Record for Agilent E3631A

CV Performance Test Record

CC Performance Test Record

Calibration Security Code

To Unsecure the Power Supply for Calibration

To Unsecure the Power Supply Without the Security Code

Calibration Count

Calibration Message

General Calibration/Adjustment Procedure

Aborting a Calibration in Progress

Calibration Record for Agilent E3631A

Error Messages

Calibration Program

Theory of Operation

Block Diagram Overview

AC Input and Bias Supplies

Floating Logic

D-to-A Converter

A-to-D Converter

Power Mesh and Control

Earth-Referenced Logic

Front Panel

Service

Operating Checklist

Is the Power Supply Inoperative?

Does the Power Supply Fail Self-Test?

Types of Service Available

Standard Repair Service (worldwide)

Express Exchange (U.S.A. only)

Repacking for Shipment