Technical data

Service Guide 5

U8001A/U8002A User’s and Service Guide 81

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- 7(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

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