Filter
Top Products
Performance and Calibration Procedures
95
Current Priority Ripple and Noise
Periodic and random deviations (PARD) in the output combine to produce a residual ac current, as well
as an ac voltage superimposed on the dc output. PARD is specified as the rms output current in a
frequency range specified in Appendix A.
NOTE: The voltage limits in Current Priority Mode are not programmable.
Action Program Commands
1. Turn off the dc source and connect the output as shown in Figure B-1d
to an ac rms voltmeter. Remember to include a 50 ohm series resistor at
the dc source end of the cable. Also connect a 16k ohm load resistor
across the HI and LO terminals.
2. Turn on the dc source and program the Current Priority mode. Program
the current to the maximum value (0.5mA).
“OUTP ON,(@1)”
“SOUR:FUNC:MODE CURR,(@1)”
“CURR 0.0005,(@1)”
3.
Read back the N3280A status to be sure that it’s in the
CC mode. This
query should return a Bit value of “
8” for CC mode.
“STAT:OPER:COND? (@1)”
4. Divide the voltage reading ac rms voltmeter by 16k (the value of the
load resistor). The result should be within the limit in the performance
test record card under Current Priority PARD Current.
Transient Response Tests
Voltage Priority, Transient Recovery Time
This test measures the time for the output voltage to recover to within the specified value following a
50% change in the load current using an RC network of a 10
µF capacitor and 0.2 ohm resistor across the
output. The test must be performed in all three bandwidths: 10kHz, 20kHz, and 30kHz.
Action Program Commands
1. Turn off the dc source and connect the output as in Figure B-1e with
the oscilloscope across the HI and LO sense terminals. Remember to
connect the RC network (10
µF & 0.2 ohm).
“OUTP OFF,(@1)”
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), the current to the maximum value (0.5A), and the
bandwidth to 10kHz.
“OUTP ON,(@1)”
“SOUR:FUNC:MODE VOLT,(@1)”
“VOLT 10,(@1)”
“CURR:LIM 0.5,(@1)”
“VOLT:ALC:BWID 10000,(@1)”
3. Program the Electronic Load as follows:
Input current = 0.25A Transient current level = 0.5A
Transient frequency = 2kHz Current slew rate = 0.167A/
µs
Transient duty cycle = 50% Turn the transient generator on.
4. Adjust the oscilloscope for a waveform similar to that in Figure B-2.
The output voltage should return to within
±40mV in less than 60µs,
45µs, or 35µs following a 0.25A to 0.5A load change. Check both
loading and unloading transients by triggering on the positive and
negative slope. Record the voltage at time “t” in the performance test
record card under Voltage Priority Transient Response Voltage.
tttt
t
v
Loading
Transient
Unloading
Transient
v
t
5. Repeat steps 2 through 4 for the 20kHz and the 30kHz bandwidths.
“VOLT:ALC:BWID 20000,(@1)”
“VOLT:ALC:BWID 30000,(@1)”