Agilent Technologies N3280A manual Ripple and Noise Tests, Voltage Priority Ripple and Noise

B - Performance and Calibration Procedures

Ripple and Noise Tests

Voltage Priority Ripple and Noise

Periodic and random deviations (PARD) in the output (ripple and noise) combine to produce a residual ac voltage superimposed on the dc output voltage. PARD is specified as the rms or peak-to-peak output voltage in the frequency range specified in Appendix A.

Action

1.Turn off the dc source and connect the output as shown in Figure B-1d to an oscilloscope (ac coupled) between the HI and LO terminals. (You can use the Model URE3 P-P Voltmeter in place of the scope.)

Remember to include a 50 ohm series resistor at the dc source end of the cable. Also connect a 20 ohm load resistor across the HI and LO terminals. Set the scope's bandwidth limit to 20 MHz. Use shielded cable < 1 meter in length if possible. Attach the cable as close to the dc source connector as possible.

2.Turn on the dc source and program the Voltage Priority mode (this is the default mode). Program the output voltage to the full-scale value (10.0V), and the current limit to the maximum value (0.5125A).

3.Note that the waveform on the oscilloscope should not exceed the peak- to-peak limit in the performance test record card under Voltage Priority PARD Voltage (peak to peak).

4.Disconnect the oscilloscope and connect an ac rms voltmeter in its place. The rms voltage reading should be within the rms limit in the performance test record card for the appropriate model under Voltage Priority PARD Voltage (rms).

5.Program the output voltage to the maximum positive value (+10.25V), and the current limit to 0.45A.

6.Read back the N3280A status to be sure that it’s in the +CL mode. This query should return a Bit value of “2” for +CL mode.

If it is not in +CL mode, decrease the current limit setting slightly.

7.Divide the voltage reading of the ac rms voltmeter by 20 (the value of the load resistor). The result should be within the limit in the performance test record card under Voltage Priority PARD Current Limit.

8.Program the output voltage to the maximum negative value (–10.25V).

9.Read back the N3280A status to be sure that it’s in the −CL mode. This query should return a Bit value of “4” for −CL mode.

If it is not in −CL mode, decrease the current limit setting slightly.

10.Divide the voltage reading of the ac rms voltmeter by 20 (the value of the load resistor). The result should be within the limit in the performance test record card under Voltage Priority PARD Current Limit.

Program Commands

“*RST”

“OUTP ON,(@1)” “VOLT 10,(@1)” “CURR:LIM 0.5125,(@1)”

“VOLT 10.25,(@1)” “CURR:LIM 0.45,(@1)”

“STAT:OPER:COND? (@1)”

“VOLT −10,(@1)”

“STAT:OPER:COND? (@1)”

94