Keithley 2651A Reference Manual page 210

Model 2651A High Power System SourceMeter® Instrument Reference Manual
The following figure shows a voltage sweep on a resistive load of 800 Ω. For this example, the
System SourceMeter instrument is programmed to sweep voltage to 10 V, limit current (6 mA) and
limit power (50 mW). When sweeping, the actual source output will vary according to the programmed
source value until the current limit is reached. As the figure shows, the output will source the
programmed value until placed in current compliance at the 6 mA limit. The sweep will then continue
(programmed I-source values will increase along the green sweep points line), but the output will
remain at the same value as when the instrument went into voltage compliance. This continues until
the programmed source value sweeps to a high enough level that the power limit line is reached (50
mW). At this point, the current and voltage will start to decrease, lowering the current and voltage
values along the DUT load line. When the last point is swept (10 V), the actual output would be 4 V
(at 5 mA).
Source I measure I, source V measure V
The High Power System SourceMeter
sourcing a voltage, you can measure voltage. Conversely, if you are sourcing current, you can
measure the output current. For these measure-source operations, the measure range is the same as
the source range.
This feature is valuable when operating with the source in compliance. When in compliance, the
programmed source value is not reached. Thus, measuring the source lets you measure the actual
output level.
2651A-901-01 Rev. A / March 2011
Figure 76: Model 2651A V-source load considerations while sweeping V
V-source sweep operation in current and power compliance
10 mA
I-meter
5 mA
(I )
M
X
Sweep
points line
5 V 10 V
Programmed V-source
(V )
S
®
Instrument can measure the function it is sourcing. When
Section 4: Theory of operation
Current
compliance
limit line
Power
compliance
limit line
4-13