KEPCO MST Series - Manual (Page 43)

MST SERIES 061813
3-11
3.8.6 VOLTAGE REFERENCE ADJUST (R47)
This procedure adjusts the internal full scale reference voltage to produce the full scale output
voltage E
MAX
when the full scale voltage is programmed.
1. Issue commands from the host computer to set the UUT to Voltage Mode, program current
limit to I
MAX
, output voltage to E
MAX
and enable the output.
2. Verify VOLTAGE MODE and OUTPUT ENABLED indicators are on.
3. Connect the voltmeter to DC output connector (see Figure 2-3) pin 5, Sense 1 (+) and
pin 2, Sense 2 (–) and verify measured value is within ± 1 LSB (1/4096) of E
MAX
. If mea-
sured value exceeds the acceptable range, adjust potentiometer R47 to E
MAX
, within the
R47 adjustment tolerance of ± 0.5 LSB (1/8192) of E
MAX
.
3.8.7 CURRENT REFERENCE ADJUST (R48)
This procedure establishes the maximum value of the internal current reference voltage so that
the readback current matches the programmed current.
1. Turn off UUT and connect precision shunt across DC Output connector pin 6, Output 1 (+),
and pin 3, Output 2 (–).
2. Turn on UUT.
3. Issue commands from the host computer to set the UUT to Current Mode, program output
current (I
O
) to 0.99 x I
MAX
, voltage limit to E
MAX
and enable the output.
4. Verify that CURRENT MODE and OUTPUT ENABLED indicators are on.
5. Issue commands from the host computer to read back current.
6. Verify that the read back value (step 5) is within ± 1 LSB (4096) of the programmed value
(step 3). If readback value exceeds acceptable range, adjust R48 for readback value within
±0.5 LSB (1/8192) of the programmed value.
3.8.8 CURRENT (I
O
) FULL SCALE ADJUST (R52)
This procedure adjusts the gain of the current sensing amplifier so that the actual full scale out-
put current matches the programmed output current.
1. Issue commands from the host computer to set the UUT to Current Mode, program output
current (I
O
) to 0.99 x I
MAX
, voltage limit to E
MAX
and disable the output. The unit must be
operating for a minimum of 20 minutes in Current Mode with output disabled to avoid drift
due to temperature fluctuations.
2. Enable the output and verify that CURRENT MODE and OUTPUT ENABLED indicators are
on.
3. Record the output current as measured across the external shunt.