56 U8001A/U8002A User’s and Service Guide
5Service Guide
Constant Current (CC) Verification
Current Programming and Readback Accuracy
This test is to verify that the current programming and
readback accuracy are within published specifications. The
accuracy of the current monitoring resistor must be 0.1% or
better.
Procedures:
1 Power- off the power supply and connect a 0.01
Ω current
shunt monitoring resistor (R
M
) across the output to be tested
and a DMM across the current monitoring resistor (R
M
).
2 Power on the power supply.
3 When the power supply is in limit mode, program the output
voltage to maximum programmable value and the current to
0 A.
4 Enable the output.
5 Wait for a few seconds for the output of the power supply to
settle. Make sure that the power supply is in CC mode.
6 Divide the voltage drop (DMM reading) across the current
monitoring resistor (R
M
) by its resistance to convert to amps
and record this value (I
O
). This value should be within the
limit of 0 A ±20 mA.
7 When the power supply is in meter mode, record the current
reading displayed on the front display of the power supply.
This value should be within the limit of I
O
±10 mA.
8 Disable the output.
9 When the power supply is in limit mode, program the output
current to full rated value, i.e. 3 A for U8001A and 5 A for
U8002A.
10 Enable the output.
11 Wait for a few seconds for the output of the power supply to
settle. Make sure that the power supply is in CC mode.
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