Keithley 7701 User Manual page 25

Biasing and measuring DUT (dual multiplexing)
WARNING Multiple channel operation is required for the following application. Multiple channel
operation should only be performed by experienced test engineers who recognize the
dangers associated with multiple channel closures.
This application demonstrates how to use the Model 7701 as a dual multiplexer to bias and measure 16 DUT. An external
source powers DUT, while the DMM of the Model 27xx measures the output of the DUT. To prevent overloading of the exter-
nal source, each DUT is powered (and measured) separately.
Figure 15 shows the connections for this application. The external source is connected to the Multiplexer 2 terminals of the
switching module, and DUT is connected to channels 1 through 16. Channels 17 through 32 are used to connect external
power to each DUT.
For this application, channels 33, 34, and 35 are to be controlled as follows:
• Closing channel 33 isolates the input measurement channels 1 through 16 (Multiplexer 1) from the external source
channels 11 through 20 (Multiplexer 2). It also connects the DUT to the external source. This channel must remain
closed while testing DUT.
• Opening channel 34 isolates the external source from the backplane of the Model 2750. This channel must remain
open while testing DUT.
• Closing channel 35 connects an input channel (1 through 16) to the DMM. This channel must remain closed while
testing DUT.
In Figure 15, channels 1 and 17 are closed to test DUT 1. The test for the other DUTs is similar except that different source and
measure channels are closed. Closed channels for each DUT test are listed as follows:
Tested Device
DUT 1
DUT 2
DUT 3
DUT 4
DUT 5
DUT 6
DUT 7
DUT 8
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Closed Channels Tested Device
1, 17, 33, and 35 DUT 9
2, 18, 33, and 35 DUT 10
3, 19, 33, and 35 DUT 11
4, 20, 33, and 35 DUT 12
5, 21, 33, and 35 DUT 13
6, 22, 33, and 35 DUT 14
7, 23, 33, and 35 DUT 15
8, 24, 33, and 35 DUT 16
Closed Channels
9, 25, 33, and 35
10, 26, 33, and 35
11, 27, 33, and 35
12, 28, 33, and 35
13, 29, 33, and 35
14, 30, 33, and 35
15, 31, 33, and 35
16, 32, 33, and 35