Tektronix 2304 Users Guide

4

MODEL 2304

QuickS tart

USER’S GUIDE

230

HIGHSPEED

RECISION

READBACK

POWER SUPPLY

Safety Precautions

product and any associated instrumentation. Although some instruments and
accessories would normally be used with non-hazardous voltages, there are situa­tions where hazardous conditions may be present.

shock hazards and are familiar with the safety precautions required to avoid possi­ble injury. Read the operating information carefully before using the product.

may be present on cable connector jacks or test fixtures. The American National
Standards Institute (ANSI) states that a shock hazard exists when voltage levels
greater than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to

expect that hazardous voltage is present in any unknown circuit before measuring.

Standard IEC 664, digital multimeter measuring circuits (e.g., Keithley Models 175A,
199, 2000, 2001, 2002, and 2010) measuring circuits are Installation Category II. All
other instruments’ signal terminals are Installation Category I and must not be con­nected to mains.

properly grounded power receptacle. Inspect the connecting cables, test leads, and
jumpers for possible wear, cracks, or breaks before each use.

instruments while power is applied to the circuit under test. ALWAYS remove power
from the entire test system and discharge any capacitors before: connecting or dis­connecting cables or jumpers, installing or removing switching cards, or making
internal changes, such as installing or removing jumpers.

side of the circuit under test or power line (earth) ground. Always make measure­ments with dry hands while standing on a dry, insulated surface capable of with­standing the voltage being measured.

the operating instructions located in the manual.

1000 volts or more, including the combined effect of normal and common mode
voltages. Use standard safety precautions to avoid personal contact with these
voltages.

personal injury or death. Always read the associated information very carefully
before performing the indicated procedure.

the instrument. Such damage may invalidate the warranty.

test cables.

The following safety precautions should be observed before using this

This product is intended for use by qualified personnel who recognize

Exercise extreme caution when a shock hazard is present. Lethal voltage

As described in the International Electrotechnical Commission (IEC)

Before operating an instrument, make sure the line cord is connected to a

For maximum safety, do not touch the product, test cables, or any other

Do not touch any object that could provide a current path to the common

The symbol on an instrument indicates that the user should refer to

The symbol on an instrument shows that it can source or measure

The WARNING heading in a manual explains dangers that might result in

The CAUTION heading in a manual explains hazards that could damage

Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all

HIGH SPEED PRECISION READBACK POWER SUPPLY

This guide is designed to familiarize users of the Keithley Model 2304 High
Speed Power Supply with the basic operating features available from the instru­ment’s front panel and via the GPIB Bus. The sequence of instructions reflects the
order in which the instrument would be configured for a typical application. As
users become more familiar with the Model 2304, it may not be necessary to follow
this sequence so strictly. For each Model 2304 operating mode, an example set of
bus commands is provided. For a reading to be performed and returned via the bus,
the :read? command must be sent after the instrument is configured to the desired
mode. While the SCPI command strings are generic, the exact programming syntax
will depend on the programming language used in the test environment.

2304 HIGH SPEED POWER SUPPLY

POWER

Figure 1. Model 2304 front panel

The Model 2304 has three operating (display) modes:

> ACTUAL V AND I — This mode reads back the actual output voltage

and current. The instrument defaults to this mode at power up.

> DVM INPUT — This mode displays the DC voltage applied to the

power supply’s DVM input.

> PULSE CURRENT — This mode is used to display high, low, or average

pulse-current measurements or to return up to 5000 measurements
from the measurement buffer, i.e., for digitizing a current waveform.

Setting the output voltage and current limit:

DISPLAY

LOCAL

MENU

ENTER

OPERATE

SET

1

Output voltage can be set from 0 to 20V. There are two ranges for current
output — 5A and 5mA. The current range can be checked or changed using the
CURRENT RANGE selection of the MENU.

3

MODEL 2304

1. Press the SET key to select the Output Settings Mode. A blinking cursor
will appear in the voltage field of the display.

2. Use the , , , buttons to key in the desired output voltage
value, then press SET. The blinking cursor will move to the current field
of the display.

3. Use the , , , buttons to key in the desired current limit, then
press SET to exit the Output Settings Mode. The display will return to
the actual V and I display mode.

GPIB commands for setting the output voltage and current limit:

:source:voltage xx.xxx ; set output voltage,

xx.xxx is between 0 and 20

:source:current:limit x.xxxx ; set output current limit,

x.xxxx is between 0 and 5

and

:sense:current:range minimum ; set to 5 mA range

or

:sense:current:range maximum ; set to 5 A range

Turning supply output on/off

2

The output of the Model 2304 is turned on and off using the front panel
OPERATE button. The word “ON” appears on the display when the output is turned
on. When the output is turned off, “OFF” is displayed.

GPIB commands for turning the supply output on/off:

:output on ; turn the supply output on

:output off ; turn the supply output off

4

HIGH SPEED PRECISION READBACK POWER SUPPLY

WARNING:NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.

WARNING:NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.

CAUTION:FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.

CAUTION:FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.

Selecting the operating (display) mode:

3

Actual V and I Mode:

This mode sets the instrument to display steady-state readback current
and voltage and to return current or voltage measurements over the GPIB bus. If
using the front panel controls, press the DISPLAY button and select the ”Actual V
and I” mode using the and buttons.

GPIB1,2 commands for selecting the Actual V and I mode:

:sense:function “voltage” ; selects voltage

measurement function

:sense:average xx ; the number of readings to

average per measurement, up
to 10 (optional command)

or

:sense:function “current” ; selects current

measurement function

:sense:average xx ; the number of readings to

average per measurement, up
to 10 (optional command)

ISOLATION FROM EARTH:

22 VOLTS MAX.

____

+++

SOURCE SENSE

OUTPUT

0-20V, 0-5A

SOURCE

DVM IN

LINE FUSE

SLOWBLOW

2.5A, 250V

LINE RATING

100-240VAC

50, 60 HZ

185VA MAX

+

MADE IN

U.S.A.

IEEE-488

(CHANGE IEEE ADDRESS

WITH FRONT PANEL MENU)

REMOTE
DISPLAY

OPTION

Figure 2. Rear panel of the Model 2304.Note the location of the digital voltmeter

inputs.

5

MODEL 2304

External

Quick

Disconnect

Test

Circuitry

Connector

+

DVM

Input

DVM +
DVM –

–

Source –
Source –

Output

Sense –
Sense +

DUT

Source +
Source +

Figure 3. Typical method of connecting the Model 2304 to a DUT.

DVM Input Mode:

This operating mode configures the Model 2304 to display the voltage
applied to the DVM input terminals and to return these readings via the bus. If using
the front panel controls, press the DISPLAY button and select DVM INPUT using the

and buttons.

GPIB commands for selecting the DVM Input Mode:

:sense:function “dvmeter” ; selects voltage

measurement function

:sense:average xx ; the number of readings to

average per measurement, up to 10

6

HIGH SPEED PRECISION READBACK POWER SUPPLY

Pulse Current Mode:

The Pulse Current Mode sets the instrument to display high, low, or aver­age pulse-current measurements and to return these readings over the bus. The
Model 2304 can perform current measurements on dynamic loads. The built-in
measurements include:

1. Peak measured current — Measures the peak (high) current of the
pulse train.

2. Idle measured current — Measures the idle (low) current of the pulse
train.

3. Average transmitted current — Measures the average current of the
pulse train.

Figure 4illustrates the high, low, and average measurements of a pulse.
The high measurement is triggered on the rising edge of the pulse and an integra­tion is performed for the time specified for the high measurement. The falling edge
of the pulse triggers the low measurement and an integration is performed for the
time specified for the low measurement. An average measurement is triggered on
the rising edge and the integration covers both the high and low periods of the
pulse, as specified by the average measurement time settings. The Model 2304 com­putes one measurement parameter (high, low or average) at a time. The desired
measurement mode can be selected with the and buttons on the front panel.

Figure 4. Pulse current measurement

7

MODEL 2304

Notes:

1. For a reading to be performed and returned via the bus, the :read?
command must be sent after the instrument is configured to the
desired mode.

2. The function “voltage,” “current,” “pcurrent,” and “dvmeter ” in the

:sense:function command must be in quotes.

Trigger level— To avoid false pulse detection, use a trigger level of up to

5A. All pulses, noise, or other transients below the set trigger level will be ignored.
Note: Pulsed current levels must exceed 5mA(the minimum trigger threshold) to be

detected.

Trigger delay— An optional trigger delay can be used to allow leading
edge pulse overshoot to settle. The integration period will not start until the trigger
delay period expires.

Integration times— The three integration time periods for pulse measure­ments can be set automatically or manually by the user.

1. The PULSE HIGH TIME, PULSE LOW TIME, and PULSE AVG TIME can
be set manually from 33µs to 833ms. Make sure an integration period
does not extend into the wrong portion of the pulse or into the next
pulse. For example, if the pulse is high for 600µs, the high integration
time must be less than 600µs. If not, the instrument will integrate a low
portion of the pulse, making the high pulse measurement erroneous.

Always factor in trigger delay when determining integration times.

2. When the PULSE AUTO TIME operation is performed, the instrument
measures the high and low periods of the first detected pulse and sets
appropriate integration times. The three integration times apply for all
subsequent pulse measurements until another PULSE AUTO TIME is
performed or the times are changed manually. The PULSE AUTO TIME
feature can detect pulses from 80µs to 833ms.

Pulsed Average readings count — The average readings count specifies how
many measurements (integrations) are performed and averaged for each displayed
reading. This is a different setting than the average readings count specified for
“Actual V and I” and “DVM meter.”

8

HIGH SPEED PRECISION READBACK POWER SUPPLY

Front Panel Pulse-current measurement procedure:

1. Set the output voltage and current limit.

2. Using the PULSE CURRENT selection of the MENU, set the trigger
level and delay (optional), integration times, and average readings
count (optional).

Important! — For maximum transient performance, always use the
ENHANCED output mode, available from the OUTPUT RESPONSE
selection from the MENU and make certain the output sense leads are
connected across the load.

3. Press OPERATE.

4. Press the DISPLAY key and select the PULSE CURRENT display type.

5. Use the and buttons to display the desired pulse measurement:
PULSE HIGH, PULSE LOW, or PULSE AVERAGE.

NOTE:With the output on, pulses will not be detected
if the trigger level is too low (an “A/D PULSE TRIG NOT DETECTED” or
“OVERFLOW” message will be displayed). Perform the following
procedure to find an appropriate trigger level.

Determining correct trigger level:

1. Turn the output on. If the trigger level is too low or too high, the “A/D
PULSE TRIG NOT DETECTED” message will be displayed briefly. If the
message does not appear, pulses are being detected, indicating that
the trigger level is valid. If so, it is unnecessary to complete this
procedure.

2. Go into the MENU, select PULSE CURRENT, then TRIGGER LEVEL.

3. Change the PULSE TRIG LEVEL and press ENTER. If the trigger level is
still too low or too high, the “A/D PULSE TRIG NOT DETECTED”
message will appear on the display again. It may take a few seconds for
the message to appear.

4. If the message appears, repeat Step 3 until a valid trigger level is found.

5. Use the MENU key to back out of the menu structure and display
pulse-current measurements.

9

MODEL 2304

GPIB commands for making pulse-current measurements:

:sense:function “pcurrent” ; selects pulsed current

measurement function

:sense:pcurrent:synchronize: tlevel x.xxxx

; specify trigger level
x.xxxx, up to 5 amps

:sense:pcurrent:average x ; number of readings to

average per measurement, up
to 100 (optional command)

:output:response enhanced ; select enhanced output

for pulsed current
measurements

:output on ; turn on supply output

and

:sense:pcurrent:time:high .xxxxxx

; specify integration time
(in sec) for high pulse
measurements

:sense:pcurrent:time: low .xxxxxx

; specify integration time
(in sec) for low pulse
measurements

:sense:pcurrent:time: high .xxxxxx

; specify integration time
(in sec) for average pulse
measurements

or

:sense:pcurrent:time:auto ; Model 2304 sets

integration times

and

:sense:pcurrent:mode high ; set up Model 2304 to

calculate and return high
pulse value

or

10

HIGH SPEED PRECISION READBACK POWER SUPPLY

:sense:pcurrent:mode low ; set up Model 2304 to

calculate and return low
pulse value

or

:sense:pcurrent:mode average ; set up Model 2304 to

calculate and return
average pulse value

:sense:pcurrent:synchronize: delay .xxxxx

; specify trigger delay in
sec, 0.1 sec maximum in 10
µs increments (optional
command)

GPIB commands to digitize a current waveform and transfer the readings via the bus:

:sense:function “pcurrent” ; selects pulsed current

measurement function

:sense:pcurrent:synchronize:
tlevel x.xxxx ; specify trigger level, up

to 5 amps

:sense:pcurrent:synchronize:
state off ; turn the trigger

synchronization off

:sense:pcurrent:average xxxx ; number of readings to

store in the buffer, up to
5000

:output:response enhanced ; select enhanced output

for pulsed current
measurements

:output on ; turn on supply output

:read:array? ; command used to return

the last array of readings

Note: This command must be used in place of the :read? command.

Conversion rate is ≈3600 rdgs/s.

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Keithley Instruments,Inc.• 28775 Aurora Road • Cleveland, Ohio 44139
440-248-0400 • Fax: [phone] • http://www.keithley.com

© Copyright 1998 Keithley Instruments, Inc.
Printed in the U.S.A. Part No. 2304-903-01 Rev A /1-98

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