Section 4: Theory of operation
2606B System SourceMeter® Instrument Reference Manual
4-10
2606B-901-01 Rev. B / May 2018
Current source operation in voltage compliance
The following figure shows what happens if the resistance of the load is increased to 200
Ω. The DUT
load line for 200
Ω intersects the voltage compliance limit line, placing the instrument in voltage
compliance. In compliance, the instrument cannot source its programmed current (100 mA). For the
200
Ω DUT, the instrument only outputs 50 mA (at the 10 V limit).
Notice that as resistance increases, the slope of the DUT load line increases. As resistance increases
and approaches infinity (open output), the 2606B sources virtually 0 mA at 10 V. Conversely, as
resistance decreases, the slope of the DUT load line decreases. At zero resistance (shorted output),
the 2606B sources 100 mA at virtually 0 V.
Figure 87: Current source operation in voltage compliance
Current source operation in power compliance
The following figure shows the results when a power limit of 600 mW is applied. As the instrument
attempts to output the programmed source value of 100 mA, the power limited voltage compliance
limit line is reached, placing the instrument in power compliance. The instrument enforces the power
compliance limit by setting the voltage compliance limit line to the new power limited voltage
compliance limit line setting (in this case, 6 V). In compliance, the instrument cannot source its
programmed current (100 mA). For a 200
Ω DUT, the instrument only outputs 30 mA (at the 6 V limit).
In this example, voltage will never exceed the programmed compliance of 10 V or the programmed
power compliance of 600 mW under any load.