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A-5
Fi
g
ure A-5. Load Transient Response Time Waveform
PARD(Ripple and Noise)
Definition: PARD is the Periodic and Random Deviation of
the dc output volta
g
e from its avera
g
e value, over a specified
bandwidth and with all other parameters maintained constant.
Constant volta
g
e 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 frequenc
y
limit
are treated as drift.
PARD(RMS) Measurement
The rms measurement is not an ideal representation of the
noise, since fairl
y
hi
g
h output noise spikes of short duration
could be present in the ripple and not appreciabl
y
increase
the rms value.
Test Parameter:
Measured Variable: Output Volta
g
e(rms)
Expected Results: Less than 200 µV rms
Test Procedure:
a. Connect the test equipment as shown in Fi
g
ure A-6.
b. Turn the suppl
y
's power on and turn CURRENT con-
trol full
y
clockwise.
c. Turn up output volta
g
e to the full rated value. Check
that the suppl
y
's CV indicator remains li
g
hted.
Reduce VOLTAGE control if not li
g
hted.
d. Check that the rms noise volta
g
e at the true rms volt-
meter is less than 200BµV.
Fi
g
ure A-6. CV PARD RMS Measurement Test Setup
PARD(Peak-to-Peak) Measurement
The peak-to-peak measurement is particularl
y
important for
applications where noise spikes could be detrimental to a
sensitive load, such as lo
g
ic circuitr
y
.
Test Parameter:
Measured Variable: Output volta
g
e(peak-to-peak)
Expected Results: Less than 1 mV p-p (20 Hz-20 MHz)
Test Procedure: