Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-23
Dual multiplexer application
This application demonstrates how to use the Model 7700 as a dual multiplexer to bias and
measure 10 DUT. An external source powers the DUT, while the DMM of the Model 2750
measures the output of the DUT. To prevent overloading of the external source, each DUT
is powered (and measured) separately.
Figure 2-9 shows the connections for this application. The external source is connected to
the Sense terminals of the switching module, and DUT is connected to channels 1 through
10. Channels 11 through 20 are used to connect external power to each DUT.
For this application, the 2-pole/4-pole relay and backplane isolation relays of the switch-
ing module are to be controlled as follows:
• Closing channel 23 isolates the input measurement channels (1 through 10) from
the external source channels (11 through 20). It also connects the DUT to the exter-
nal source. This channel must remain closed while testing DUT.
• Opening channel 24 isolates the external source from the backplane of the Model
2750. This channel must remain open while testing DUT.
• Closing channel 25 connects an input channel (1 through 10) to the DMM.
In Figure 2-9, channels 1 and 11 are closed to test DUT 1. A more detailed view of the test
for DUT 1 is shown in Figure 2-10. The test for the other DUTs is similar except that dif-
ferent source and measure channels are closed. Closed channels for each DUT test are
listed as follows:
NOTE Do not use this application to measure the temperature of the DUT using a
thermocouple with the INTernal or EXTernal reference junction selected. The
SIMulated reference junction will instead be used resulting in invalid readings.
The “ERR” annunciator will turn on to indicate that the integrity of the
temperature reading is questionable.
Tested
device Closed channels
Tested
device Closed channels
DUT 1 1, 11, 23 and 25 DUT 6 6, 16, 23 and 25
DUT 2 2, 12, 23 and 25 DUT 7 7, 17, 23 and 25
DUT 3 3, 13, 23 and 25 DUT 8 8, 18, 23 and 25
DUT 4 4, 14, 23 and 25 DUT 9 9, 19, 23 and 25
DUT 5 5, 15, 23 and 25 DUT 10 10, 20, 23 and 25
2750-900-01.book Page 23 Wednesday, August 3, 2011 7:56 AM
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