Keithley 6430 Instruction Manual page 120

5-12 Source-Measure Concepts
Where within the boundaries the SourceMeter operates depends on the load (DUT) that is
connected to its output. Figure 5-6 shows operation examples for resistive loads that are 50Ω
and 200Ω, respectively. For these examples, the SourceMeter is programmed to source 100mA
and limit 10V.
In Figure 5-6A, the SourceMeter is sourcing 100mA to the 50Ω load and subsequently mea-
sures 5V. As shown, the load line for 50Ω intersects the 100mA current source line at 5V.
Figure 5-6B shows what happens if the resistance of the load is increased to 200Ω. The DUT
load line for 200Ω intersects the voltage compliance limit line placing the SourceMeter in com-
pliance. In compliance, the SourceMeter will not be able to source its programmed current
(100mA). For the 200Ω DUT, the SourceMeter will only output 50mA (at the 10V limit).
Notice that as resistance increases, the slope of the DUT load line increases. As resistance
approaches infinity (open output), the SourceMeter will source virtually 0mA at 10V. Con-
versely, as resistance decreases, the slope of the DUT load line decreases. At zero resistance
(shorted output), the SourceMeter will source 100mA at virtually 0V.
Regardless of the load, voltage will never exceed the programmed compliance of 10V.