Tektronix PS280 User manual

User Manual
PS280 & PS283
DC Power Supplies
070-8355-03

Copyright Tektronix, Inc. 1991. All rights reserved.
Tektronix products are covered by U.S. and foreign patents, issued and
pending. Information in this publication supercedes that in all previously
published material. Specifications and price change privileges reserved.
Tektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000
TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.

WARRANTY
Tektronix warrants that this product will be free from defects in materials and
workmanship for a period of one (1) year from the date of shipment. If any such product
proves defective during this warranty period, Tektronix, at its option, either will repair the
defective product without charge for parts and labor, or will provide a replacement in
exchange for the defective product.
In order to obtain service under this warranty, Customer must notify Tektronix of the defect
before the expiration of the warranty period and make suitable arrangements for the
performance of service. Customer shall be responsible for packaging and shipping the
defective product to the service center designated by Tektronix, with shipping charges
prepaid. Tektronix shall pay for the return of the product to Customer if the shipment is to
a location within the country in which the Tektronix service center is located. Customer
shall be responsible for paying all shipping charges, duties, taxes, and any other charges for
products returned to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or
improper or inadequate maintenance and care. Tektronix shall not be obligated to furnish
service under this warranty a) to repair damage resulting from attempts by personnel other
than Tektronix representatives to install, repair or service the product; b) to repair damage
resulting from improper use or connection to incompatible equipment; or c) to service a
product that has been modified or integrated with other products when the effect of such
modification or integration increases the time or difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS
PRODUCT IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR
IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE
DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY
PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY.
TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY
INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS
ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.

PS280 & PS283 User Manual i
Table of Contents
General Safety Summary iii. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Getting Started 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing the Power Supply for Use 2. . . . . . . . . . . . . . . . . . . . .
Front Panel 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning On the Instrument 8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reference 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Constant Voltage/Constant Current Crossover 9. . . . . . . . . . . . .
Setting the Current Limit 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Modes 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Independent Modes 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tracking Modes 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix A: Specifications 25. . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B: Maintenance 29. . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing for Shipment 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix C: Replaceable Parts 33. . . . . . . . . . . . . . . . . . . . . . .
Standard Accessories 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents
ii PS280 & PS283 User Manual
List of Figures
Figure 1: Line Voltage Selectors, Power Input,
and Fuse Locations 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2: PS280 or PS283 Front Panel 4. . . . . . . . . . . . . . . . . . .
Figure 3: Constant Voltage/Constant Current Crossover 10. . . . . .
Figure 4: Independent Floating Application 12. . . . . . . . . . . . . . .
Figure 5: Independent Common Ground-Referenced
Application 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6: Independent Ground-Referenced Split Application 15. .
Figure 7: Three Ground-Referenced Negative Power Supplies 16
Figure 8: Three Ground-Referenced Positive Power Supplies 17.
Figure 9: Independent Positive Stacked Application 18. . . . . . . . .
Figure 10: Independent Negative Stacked Application 19. . . . . . .
Figure 11: Series Tracking Inside the PS280 or PS283 20. . . . . . .
Figure 12: Series Tracking Application 21. . . . . . . . . . . . . . . . . . .
Figure 13: Parallel Tracking Inside the PS280 or PS283 23. . . . .
Figure 14: Parallel Tracking Application 24. . . . . . . . . . . . . . . . .

PS280 & PS283 User Manual iii
General Safety Summary
Review the following safety precautions to avoid injury and prevent
damage to this product or any products connected to it.
Injury Precautions
Use Proper Power Cord
To avoid fire hazard, use only the power cord specified for this
product.
Avoid Electric Overload
To avoid electric shock or fire hazard, do not apply a voltage to a
terminal that is outside the range specified for that terminal.
Ground the Product
This product is grounded through the grounding conductor of the
power cord. To avoid electric shock, the grounding conductor must
be connected to earth ground. Before making connections to the
input or output terminals of the product, ensure that the product is
properly grounded.
Do Not Operate Without Covers
To avoid electric shock or fire hazard, do not operate this product
with covers or panels removed.
Use Proper Fuse
To avoid fire hazard, use only the fuse type and rating specified for
this product.

General Safety Summary
iv PS280 & PS283 User Manual
Do Not Operate in Wet/DampConditions
To avoid electric shock, do not operate this product in wet or damp
conditions.
Do Not Operate in Explosive Atmosphere
To avoid injury or fire hazard, do not operate this product in an
explosive atmosphere.
Product Damage Precautions
Use Proper Voltage Setting
Before applying power, ensure that the line selector is in the proper
position for the power source being used.
Provide Proper Ventilation
To prevent product overheating, provide proper ventilation.
Do Not Operate With SuspectedFailures
If you suspect there is damage to this product, have it inspected by
qualified service personnel.
Safety Terms and Symbols
Terms in This Manual
These terms may appear in this manual:
WARNING. Warning statements identify conditions or practices that
could result in injury or loss of life.

General Safety Summary
PS280 & PS283 User Manual v
CAUTION. Caution statements identify conditions or practices that
could result in damage to this product or other property.
Terms on the Product
These terms may appear on the product:
DANGER indicates an injury hazard immediately accessible as you
read the marking.
WARNING indicates an injury hazard not immediately accessible as
you read the marking.
CAUTION indicates a hazard to property including the product.
Symbols on the Product
The following symbols may appear on the product:
DANGER
High Voltage ProtectiveGround (Earth)Terminal ATTENTION Referto
Manual
Double
Insulated
Certifications and Compliances
CSA Certified Power Cords
CSA Certification includes the products and power cords appropriate
for use in the North America power network. All other power cords
supplied are approved for the country of use.

General Safety Summary
vi PS280 & PS283 User Manual

PS280 & PS283 User Manual 1
Getting Started
The Tektronix PS280 or PS283 Laboratory DC Power Supply is a
multifunction bench or portable instrument. This regulated power
supply provides a fixed 5 V output for powering logic circuits and
two variable outputs for a wide variety of test and experimental uses.
The PS280 or PS283 contains two identical, independently adjustable
DC power supplies that you can vary from 0 to 30 V. The current on
the PS280 variable power supplies varies from 0 to 2 A. The current
on the PS283 variable power supplies varies from 0 to 1 A. In all
other respects the instruments are identical. Unless otherwise noted,
descriptions and procedures in this manual apply to both instruments.
Front panel switches select one of three modes of operation:
HIndependent — In this mode, the output voltage and current of
each supply can be controlled independently.
HSeries — In this tracking mode, the variable outputs are
connected in series, and the controls of the master power supply
adjust the voltages or currents of both power supplies. Series
mode allows the power supplies to be varied from 0 to 60 V at 0
to 2 A for the PS280, or 0 to 1 A for the PS283.
HParallel — In this tracking mode, the variable outputs are
connected in parallel, and the controls of the master power supply
adjust the voltages or currents of both power supplies. Parallel
mode allows the power supplies to be varied from 0 to 4 A for the
PS280 at 0 to 30 V, or from 0 to 2 A at 0 to 30 V for the PS283.

Getting Started
2PS280 & PS283 User Manual
Preparing the Power Supply for Use
Check the following items prior to operating the Laboratory DC
Power Supply for the first time (see Figure 1 for locations of items 1
through 3):
1
3
2
Figure 1: Line Voltage Selectors, Power Input, and Fuse Locations
CAUTION. To prevent damage to the instrument, set the line voltage
selectors to the proper voltage setting and install the correct line
voltage fuse before operating the equipment.
1. Set the line voltage selectors to the input line voltage. These
selectors connect internal wiring for various line voltages. This
product is intended to operate from a power source that does not
supply more than 250 VRMS between the supply conductors or
between either supply conductor and ground. For line voltage
ranges, refer to Appendix A: Specifications on page 25.
WARNING. To prevent electrical shock, unplug the power cord and
disconnect the test leads from the circuit before checking or
replacing the fuse.
2. Check that the correct line fuse is installed. The line fuse
provides protection if the equipment malfunctions or an overload

Getting Started
PS280 & PS283 User Manual 3
occurs. Refer to Appendix C: Replaceable Parts on page 33 for
fuse part numbers.
WARNING. To prevent electrical shock, connect the power cord to a
properly grounded power source. The outside (ground) of this
connector is connected through the equipment to the power source
ground. Do not remove the ground lug from the power cord for any
reason.
3. Connect the input power cord. Use only the power cords specified
for this equipment. Refer to Appendix C: Replaceable Parts on
page 33 for power cord part numbers.

Getting Started
4PS280 & PS283 User Manual
Front Panel
Figure 2 shows the front-panel controls, connectors, and indicators
with brief descriptions following the figure.
13456 8
22
1918151211 13 17 219
27
20161410
Figure 2: PS280 or PS283 Front Panel
1. LED Display. Lights when the instrument is turned on. The
numbers indicate the voltage or current produced by the left
variable power supply.
2. AMPS/VOLTS Switch. This switch selects whether the LED
display for the left variable power supply shows the current or the
voltage. If the switch is pushed to the left, the display shows the
current. If the switch is pushed to the right, the display shows the
voltage.

Getting Started
PS280 & PS283 User Manual 5
3. AMPS Indicator. Lights when AMPS is selected with the
AMPS/VOLTS switch for the left variable power supply.
4. VOLTS Indicator. Lights when VOLTS is selected with
AMPS/VOLTS switch for the left variable power supply.
5. AMPS Indicator. Lights when AMPS is selected with the
AMPS/VOLTS switch for the right variable power supply.
6. VOLTS Indicator. Lights when VOLTS is selected with
AMPS/VOLTS switch for the right variable power supply.
7. AMPS/VOLTS Switch. This switch selects whether the LED
display for the right variable power supply shows the current or
the voltage. If the switch is pushed to the left, the display shows
the current. If the switch is pushed to the right, the display shows
the voltage.
8. LED Display. Lights when the instrument is turned on. The
numbers indicate the voltage or current produced by the right
variable power supply.
9. POWER Button. Turns on the instrument when pressed. When
pressed again, it turns off the instrument.
10.CURRENT Knob. Use this control to set the output current for
the right, variable power supply. If the instrument is in a tracking
mode, the left power supply is the slave and the CURRENT
knob has no effect.
11. C.C. Indicator. If this is lighted, the left variable power supply is
producing a constant current. See Figure 3 on page 10 for an
illustration of the constant voltage/constant current cross-
over point.
12.C.V. Indicator. If this is lighted, the left variable power supply is
producing a constant voltage. See Figure 3 on page 10 for an
illustration of the constant voltage/constant current cross-
over point.

Getting Started
6PS280 & PS283 User Manual
13.Output Terminals. These terminals for the left, variable power
supply allow you to plug in the test leads as follows:
HThe red terminal on the right is the positive polarity output
terminal. It is indicated by a + sign above it.
HThe black terminal on the left is the negative polarity output
terminal. It is indicated by a – sign above it.
HThe green terminal in the middle is the earth and chassis
ground.
14.VOLTAGE Knob. Allows you to set the output voltage for the
left variable power supply. If the instrument is in a tracking
mode, the left power supply is the slave and the VOLTAGE knob
has no effect.
15.TRACKING Buttons. These buttons select the test mode of the
instrument. The PS280 or PS283 features two tracking modes:
series and parallel. If both push-button switches are disengaged
(out), the two variable power supplies operate independently. If
the left switch is pushed in, the instrument operates in series
mode. If both switches are pushed in, the instrument operates in
parallel mode.
In series mode, the master power supply controls the voltage for
both power supplies, which can then range from 0 to 60 V. Refer
to Series on page 20 for further details.
In parallel mode, the master power supply controls both the
voltage and the current for both power supplies. The current can
then range from 0 to 4 A (0 to 2 A for the PS283). Refer to
Parallel on page 22 for further details.
16.CURRENT Knob. Use this control to set the output current for
the right, variable power supply. If the instrument is in a tracking
mode, the right power supply is the master and the CURRENT
knob affects both variable power supplies.

Getting Started
PS280 & PS283 User Manual 7
17.Output Terminals. These terminals for the right, variable power
supply allow you to plug in the test leads as follows:
HThe red terminal on the right is the positive polarity output
terminal. It is indicated by a plus (+) sign above it.
HThe black terminal on the left is the negative polarity output
terminal. It is indicated by a minus (–) sign above it.
HThe green terminal in the middle is the earth and chassis
ground.
18.C.C. Indicator. If this is lighted, the power supply is producing a
constant current. See Figure 3 on page 10 for an illustration of the
constant voltage/constant current crossover point.
19.C.V. Indicator. If this is lighted, the power supply is producing a
constant voltage. See Figure 3 on page 10 for an illustration of
the constant voltage/constant current crossover point.
20.VOLTAGE Knob. Allows you to set the output voltage for the
right variable power supply. If the instrument is in a tracking
mode, the right power supply is the master and the VOLTAGE
knob affects both variable power supplies.
21.Output Terminals. These terminals for the 5 V FIXED power
supply allow you to plug in the test leads as follows:
HThe red terminal on the right is the positive polarity output
terminal.
HThe black terminal on the left is the negative polarity output
terminal.
22.The overload indicator lights when the current on the 5 V FIXED
power supply becomes too large.

Getting Started
8PS280 & PS283 User Manual
Turning On the Instrument
After you have ensured that the PS280 or PS283 is set up for the
proper line voltage and has the proper fuse (refer to Preparing the
Power Supply for Use on page 2), you are ready to turn it on.
CAUTION. To avoid damaging the PS280 or PS283, do not use it
when the ambient air temperature exceeds 40°C. Also, allow
adequate space at the rear of the instrument to permit the heat sink
to radiate heat.
1. Ensure that the POWER button is disengaged (out) and that the
instrument is turned off.
2. Plug the power cord into an appropriate power source.
3. Turn both VOLTAGE knobs counterclockwise to the minimum
setting.
4. Press the POWER button. The LED displays light up.

PS280 & PS283 User Manual 9
Reference
This section tells how to set the PS280 or PS283 current limit. It also
explains the constant voltage/constant current crossover characteris-
tic of the instrument. Finally, the section includes procedures for
using the instrument in both independent and tracking modes and
provides examples of a variety of applications.
Constant Voltage/Constant Current Crossover
The PS280 or PS283 DC Power Supply features a constant
voltage/constant current automatic crossover. This feature permits
continuous operation in the transition from constant-voltage mode to
constant-current mode as the load changes. The intersection of the
constant-current and constant-voltage modes is called the crossover
point. Figure 3 on page 10 shows the relationship between the load
and the crossover point.
For example, if the load is such that the power supply is operating in
constant-voltage mode, the PS280 or PS283 provides a regulated
output voltage. The output voltage remains constant as the load
increases until the preset current limit is reached. Then the crossover
occurs. At that point, the output current becomes constant and the
output voltage drops in proportion to further load increases.
Crossover is indicated by the front panel red C.C. and green C.V.
indicator lights. If the C.V. indicator is lighted, the instrument is
operating in constant-voltage mode. If the C.C. indicator is lighted,
the instrument is operating in constant-current mode.
Crossover from the constant-current mode to the constant-voltage
mode also occurs automatically in response to a decrease in load. For
example, suppose you are charging a 12 V battery. Initially, the open
circuit voltage of the power supply is preset for 13.8 V. A low battery
places a heavy load on the power supply, and it operates in
constant-current mode. You adjust the instrument to charge the
battery at the rate of 1 A. As the battery becomes charged and its
voltage approaches 13.8 V, the load decreases to the point where the
battery no longer demands the full 1 A charging rate. The PS280 or
PS283 then crosses over to constant-voltage mode.

Reference
10 PS280 & PS283 User Manual
VO
Maximum
Output
Voltage
Constant Current
Range
Constant
Voltage
Range
Crossover Point
IOMaximum
Output Current
Figure 3: Constant Voltage/ConstantCurrentCrossover
Setting the Current Limit
Before you begin using the PS280 or PS283 to power a device, you
should set its current limit lower than the maximum safe current for
the device to be powered.
CAUTION. In order to avoid damaging your device with a current
overload, set the current limit on the PS280 or PS283 before you
connect it to your device.
1. Determine the maximum safe current for the device to be
powered.
2. With the test lead, temporarily short the positive and the negative
output terminals of the power supply together.