Keysight U8001A - Page 74

5 Service Guide
74 Keysight U8001A/U8002A User’s and Service Guide
CC noise
CC noise is specified as the RMS output current in a frequency range 20 Hz to
20 MHz with the power supply in constant current operation.
Procedures:
1 Power off the power supply and connect the output to be tested as shown in
Figure 5-2(D) to an AC/DC converter and load resistor (10
Ω for U8001A and
6
Ω for U8002A).
2 Power on the power supply.
3 When the display is in the limit mode, program the output voltage to maximum
programmable value and output current to full rated value, i.e. 3 A for U8001A
and 5 A for U8002A.
4 Enable the output.
5 Make sure that the power supply is in CC mode. If not, adjust the resistive load
so that the output voltage drops slightly until the power supply is in CC mode.
6 Configure the differential amplifier as follow:
– Set to AC mode (positive and negative) to removes the DC component
– Set to differential mode
– Set gain to x10
– Set attenuation to 1
– Set low pass filter to 20 MHz bandwidth limit to filter out input signal which
contains higher frequency
– Set to zero precision voltage generator
– Set input impedance to 1 M
Ω
7 Configure the RMS voltmeter as follow:
– Set high pass filter to10 Hz
– AC coupling
8 Divide the reading of the RMS voltmeter by 10 and then multiply the result by
5 to get the RMS noise measurement. The result should not exceed the RMS
limits of 3 mA
RMS
.