Section 4: Theory of operation
Model 2657A High Power System SourceMeter® Instrument Reference Manual
4-16
2657A-901-01 Rev. B/December 2012
I-source sink operating boundaries
The quadrant within which the Model 2657A operates depends on the device-under-test (DUT)
connected to the Model 2657A output. The following example illustrates this operation by using the
Model 2657A configured to provide a constant current to discharge a 1000 V power source (a
battery).
When using the I-Source as a sink, always set the voltage compliance limit and configure
(on page 2-65) to levels that are higher than the external voltage level. Failure to do
so could result in excessive current flow into the Model 2657A and incorrect measurements.
Figure 82: Sourcing current sink operation example
The voltage compliance limit applies both to positive and negative voltages. For example, if you set
the voltage compliance limit to 1500 V, the voltage limit applies to ±1500 V.
For this example, the Model 2657A is programmed to source
−
50 mA (the constant current) and to
limit voltage to 1500 V. When the SMU turns on, it begins sinking current as determined by the
programmed I-source level (-50 mA), causing a decrease in the battery voltage. If the battery were
ideal and could be charged negatively, its voltage would then continue to decrease until it is
negatively charged at
−
1500 V (shown by the green arrow in the following figure), at which point the
SMU would be in voltage compliance.
CAUTION
I
SMU
+
-
2657A
SMU
+
-
1000 V
-50 mA
NOTE
Summary of Contents for 2657A
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