Technical data

76 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
±20 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.