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Verification and Performance Tests - 2
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e. Divide the voltage drop (DVM reading) across the current monitoring resistor by its resistance to convert to
amps and record this value (Iout). Also, record the current reading that appears on the front panel display. The
readings should be within the limits specified in the performance test record card for the appropriate model
under CC PROGRAMMING @ FULL-SCALE.
Current Sink (-CC) Operation
This test verifies current sink operation and readback.
a. Turn off the supply and connect the output as shown in Figure 2-1a, except connect a dc power supply in place
of the electronic load as indicated. Connect the DMM across the current shunt.
b. Set the external power supply to 5 V and the current limit approximately 20% above the full scale current rating
of the supply under test.
c. Turn on the supply under test and program the output voltage to zero and full scale output current. The current
on the UUT display should be approximately full scale current negative.
d. Divide the voltage drop across the current monitoring resistor by its resistance to obtain the current sink value in
amps and subtract this from the current reading on the display. The difference between the readings should be
within the limits specified in the performance test record chart under CURRENT SINK READBACK.
Low Range Current Readback Accuracy
This test verifies the readback accuracy of the 20 milliampere current range.
a. Turn off the supply and connect the output as shown in Figure 2-1b. Set the DMM to operate in current mode.
b. Turn on the supply under test and program the output voltage to zero and full scale output current. The current
on the UUT display should be approximately 0 mA.
c. Record the current reading on the DMM and the reading on the front panel display. The difference between the
two readings should be within the limits specified in the performance test record chart under 20mA RANGE
CURRENT READBACK ACCURACY @ 0A.
d. Program the output voltage to 20V and record the current reading on the DMM and the reading on the front
panel display. The difference between the readings should be within the limits specified in the performance test
record chart for the appropriate model under 20mA RANGE CURRENT READBACK ACCURACY @ 20mA
e. Turn off the supply and connect the output and an external supply as shown in Figure 2-1c. Set the DMM to
operate in current mode.
f. Turn on the external supply and program it to 20 V and 1 amp. Then program the supply under test to zero volts
and 1 amp. The UUT display should read approximately −20 mA.
c. Record the current reading on the DMM and the reading on the front panel display. The difference between the
two readings should be within the limits specified in the performance test record chart under 20mA RANGE
CURRENT READBACK ACCURACY @ −20 mA.
CC Load and Line Regulation
These tests (CC Load Effect and CC Source Effect given below) are tests of the dc regulation of the power supply's
output current. To insure that the values read are not the instantaneous measurement of the ac peaks of the output
current ripple, several dc measurements should be made and the average of these readings calculated. An example of
how to do this is given below using an Agilent 3458A System Voltmeter programmed from the front panel. Set up
the voltmeter and execute the "Average Reading" program follows:
a. Program 10 power line cycles per sample by pressing NPLC 1 0 ENTER .
b. Program 100 samples per trigger by pressing (N Rdgs/Trig) 1 0 0 ENTER .