Agilent Technologies 6622A Service Manual page 36

g. Program the output voltage in a loop which alternately
programs the output voltage between 0.4 V and the
High Range Full Scale Voltage value (20 .V for
40WLV/80WLV outputs or 50 V for 40WHV/80WHV
outputs) by running the following program:
10 OUTPUT 705;"VSET < ch >, < 20 or 50 >"
20 WAIT 0.05
30 OUTPUT 705;"VSET <ch>, .4"
40 WAIT 0.05
50 GOTO 10
60 END
The tested output's CV annunciator should remain on at all
times while the test is in progress.
h. Observe Channel A on the oscilloscope and adjust for a
stationary waveform by using Channel A as the trigger
source set to trigger on a positive edge. Be sure to
trigger as close as possible to the time when the output
voltage just begins to rise.
i. On Channel A, observe the output voltage transition
from the scope's bottom horizontal line to the High
Range Full Scale Voltage. Look for a smooth
exponential waveform with no "kinks" or aberrations.
Perform a time constant check by insuring that the
output voltage rises to about 63% of the High Range
Full Scale Voltage
(40WLV/80WLV outputs) or 750 µs. (40WHV/80WHV
outputs). Refer to the Channel A waveform shown in
Figure 3-7.
j. Now observe Channel B on the oscilloscope while
maintaining the trigger on Channel A as in step h. Note
the series supply bucks out the Full Scale Output
Voltage and that the waveform is clamped at
approximately -0.6 V and rises to the top horizontal line
when the output voltage is at full scale. The diodes (see
Figure 3-6) prevent gross overload of Channel B (which
is set at 50 mV division) allowing examination of the
"tail" of the exponential waveform. The output voltage
should be within 20 mV of its final settling value on the
top horizontal line is less than 2 msec. for 40WLV
/80WLV outputs and within 50 mV in less than 6 msec.
for 40WHV/80WHV outputs.
k. Repeat steps a through j for each output in your supply.
3-18 Transient Recovery Time. This test measures the time
for the output voltage to recover to within the specified
value following a change from a low current value to the
Low Range Full Scale Current value.
a. Turn off the supply and connect the output to be tested
as shown in Figure 3-8.
b. Turn on the supply and select the output to be tested
(OUTPUT SELECT key on the front panel).
NOTE
in less than 250
c. Program the selected output's voltage to the Low Range
Full Scale Voltage value and the current to the Low
Range Maximum Programmable Current value (see
Table 3-2).
d. With R2 disconnected, adjust R1 for 300 mA (for
40WLV/80WLV outputs) or 150 mA (for 40WHV/
80WHV outputs) as indicated on the front panel
display.
µsec.
e. Connect R2 and adjust to read the Low Range Full Scale
current value on the front panel display. Note that the
CV annunciator should be on. If it is not on, readjust R2
until it is on.
f. Set the oscilloscope to 50 mv/div, ac coupled, 10
us/div, internal trigger, normal, and - slope.
g. Turn on the load switch to perform the transient
response test. Alternatively, remove R1 and modulate
an electronic load between 300 mA (40WLV/80WLV
outputs) or 150 mA (40WHV/80WHV outputs) and the
Low Range Full Scale Current value. Note that if an
electronic load is used, the load's current rise time must
be less than 25 µsec to perform an adequate test. If a
load with longer rise time is used, the transient
response recovery time may appear to be out of
specification.
h. Adjust the oscilloscope trigger level for a stationary
waveform as shown in Figure 3-9 and check that the
loading transient is within 75 mV of its final value in
less than 75 , µs.
i. Change the oscilloscope settings to + slope and repeat
steps g and h for the unloading transient (see Figure 3-
9).
j. Repeat steps a through i for each output in your supply.
3-8