Keysight e3620a, Operating And Owners Manual

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A-4
Figure A-6. Ripple and Noise rms Measurement Test
Setup
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.
To measure the ripple and noise of the peak-to-peak value on
each output supply output:
a. Connect the test equipment across the output of the V1
supply as shown in Figure A-6 , but replace the true rms
voltmeter with the oscilloscope.
b. Turn on the supply and push the V1 METER switch in.
c. Adjust the output of the V1 supply to 25.0 volts.
d. Set the oscilloscope to AC mode and bandwidth to 20 MHz.
e. Check that the peak-to-peak noise is less than 1.5 mV.
f.
Repeat steps (a) through (e) for the V2 supply.
Common Mode Current (CMI)
Definition : Common mode current is that AC current compo-
nent which exists between any or all supply or output lines
and chassis ground.
To measure the common mode current:
a. Connect the full load for the V1 output terminal.
b. Connect a 100 k

resistor(R
S
) and a 2200 pF capacitor
in parallel between V1 - terminal and chassis ground.
c. Connect the DVM across R
S
. Operate the DVM in AC
voltage mode.
d. Turn on the supply.
e. Record the voltage across R
S
and convert it to current by
dividing this voltage by R
S
.
f. Check that the current is less than 1

A.
g. Repeat steps (a) through (f) for the V2 supply.
Load Transient Response Time
Definition : This is the time for the output voltage to return to
within a specified band around its voltage following a change
from full load to half load or half load to full load.
To measure the load transient response time:
a. Connect the test equipment across the output of the V1
supply as shown in Figure A-5 , but replace the DVM with
the oscilloscope. Operate the electronic load in constant
current mode.
b. Turn on the supply and push the V1 METER switch in.
c. Turn up V1 output voltage to 25.0 volts.
d. Set the electronic load to transient operation mode
between one half of supply's full rated value and supply's
full rated value at a 1 kHz rate with 50% duty cycle.
e. Set the oscilloscope for AC coupling, internal sync and
lock on either the positive or negative load transient.
f. Adjust the oscilloscope to display transients as shown in
Figure A-7 .
g. Check that the pulse width (t
2
-t
1
) of the transients at 15
mV from the base line is no more than 50

sec as shown.
h. Repeat steps (a) through (g) for the V2 supply.
Stability (Drift)
Definition: The change in output voltage (DC to 20 Hz) for
the first 8 hours following a 30-minute warm-up period with
constant input line voltage, constant load resistance and con-
stant ambient temperature.
To measure the stability:
a. Connect the test equipment across the output of the V1
supply as shown in Figure A-5 .
b. Operate the electronic load in constant current mode and
set its current to 1.000 A.
c. Turn on the supply and push the V1 METER switch in.
d. Turn up V1 output voltage to 25.0 volts as read on the
digital voltmeter.
e. After a 30-minute warm-up, note the voltage on DVM.
f.
The output voltage reading should deviate less than 0.1%
plus 5 mV from the reading obtained in step (e) over a
period of 8 hours.
g. Repeat steps (a) through (f) for the V2 supply.