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Constant Current (CC) Tests
CC Setup
Follow the general setup instructions in the Measurement Techniques paragraph and the specific
instructions given in the following paragraphs.
Current Programming and Readback Accuracy
This test verifies that the current programming and readback are within specification.
a.
Turn off the supply and connect the current monitoring resistor across the power supply output and
the DVM across the resistor as shown in Figure 2-1a. See "Current Monitoring Resistor" for
connection information.
b. Turn on the supply and program the output voltage to 5 V and the current to zero.
c.
Divide the voltage drop (DVM reading) across the current monitoring resistor by its resistance to
convert to amps and record this value (Iout). The reading should be within the limits specified in the
performance test record card for the appropriate model under CC PROGRAMMING @ 0 AMPS.
d. Set the current readback range to High and program the output current to 20mA. Repeat step C to get
the Iout. Record the current reading on the front panel display. The reading should be within the limits
specified in the performance test record card for the appropriate model under Current Readback
Accuracy @ 20mA (High Range).
e.
Program the output current to full-scale .
f.
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.
Verification and Performance Tests - 2
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