Agilent Technologies 6571A, Service Manual

Page: 19 / 161

Verification 19
Constant Current (CC) Tests
Test Setup
Connect the appropriate current monitoring resistor (see Table 2-l) as shown in Figure 2-1B. The accuracy of the resistor
must be as specified in the table.
Test Procedures
The test procedures are given in Table 2-5. The tests are independent and may be performed in any order. The CC tests are:
•
Current Programming and Readback Accuracy.
•
Current Sink (-CC) Operation.
•
CC Load Effect.
•
CC Source Effect.
•
CC Noise (PARD).
Table 2-5. Constant Current (CC) Tests
Action Normal Result
Current Programming and Readback Accuracy
This test verifies that the current programming and readback are within specification.
1 Turn off the power supply and connect the current monitoring resistor as
shown in Figure 2-1B. Connect a DVM across the resistor.
2 Turn on the power supply and program the output for 5 volts and 0
amperes.
3 Short the load.
4 Observe the DVM voltage reading. Divide this by the resistance of the
current monitor resistor. Record the result as the Low Current value. Value within specified Low Current
limits.
5 Record the front panel display readback. Value within specified readback limits.
6 Program output current to full scale (see Table 2-2).
7 Repeat Steps 4 and 5. Both current readings within specified
High Current and readback limits.
Current Sink (CC-) and Readback Accuracy
This test verifies current sink operation and readback accuracy.
1 Turn off the power supply. Connect the output as shown in Figure 2-1B,
except replace the Electronic Load with the external test supply specified
in Table 2-1.
2 Set the external supply to 5 volts and its current limit to the -CC value of
the power supply under test (see Table 2-2).
3 Turn on the power supply under test and program its output voltage to 0.