A-5
Figure A-5. Load Transient Response Time Waveform
PARD(Ripple and Noise)
Definition: PARD is the Periodic and Random Deviation of
the dc output voltage from its average value, over a specified
bandwidth and with all other parameters maintained constant.
Constant voltage PARD is measured in the root-mean-
square(rms) or peak-to-peak(pp) values over a 20 Hz to 20
MHz bandwidth. Fluctuations below the lower frequency limit
are treated as drift.
PARD(RMS) Measurement
The rms measurement is not an ideal representation of the
noise, since fairly high output noise spikes of short duration
could be present in the ripple and not appreciably increase
the rms value.
Test Parameter:
Measured Variable: Output Voltage(rms)
Expected Results: Less than 200
µ
V rms
Test Procedure:
a.
Connect the test equipment as shown in Figure A-6.
b.
Turn the supply's power on and turn CURRENT con-
trol fully clockwise.
c.
Turn up output voltage to the full rated value. Check
that the supply's CV indicator remains lighted.
Reduce VOLTAGE control if not lighted.
d.
Check that the rms noise voltage at the true rms volt-
meter is less than 200
B
µ
V.
Figure A-6. CV PARD RMS Measurement Test Setup
PARD(Peak-to-Peak) Measurement
The peak-to-peak measurement is particularly important for
applications where noise spikes could be detrimental to a
sensitive load, such as logic circuitry.
Test Parameter:
Measured Variable: Output voltage(peak-to-peak)
Expected Results: Less than 1 mV p-p (20 Hz-20 MHz)
Test Procedure:
