User Manual

6-20 Source-Measure Concepts 2400 Series SourceMeter
®
User’s Manual
Figure 6-12 shows the limit lines for the V-Source. The voltage source limit line
represents the maximum source value possible for the presently selected voltage
source range. For example, if on the 20V source range, the voltage source limit
line is at 21V. The current compliance limit line represents the actual compliance
in effect. Remember that compliance can be real or range. (See “Compliance
limit,” page 6-2.) These limit lines are boundaries that represent the operating lim-
its of the SourceMeter for this quadrant of operation. The operating point can be
anywhere inside (or on) these limit lines. The limit line boundaries for the other
quadrants are similar.
Figure 6-12
V-Source limit lines
Current compliance boundaries
Where within the boundaries the SourceMeter operates depends on the load
(DUT) that is connected to the output. Figure 6-13 shows operation examples for
resistive loads that are 2k and 800, respectively. For these examples, the
SourceMeter is programmed to source 50V and limit 50mA.
In Figure 6-13A, the SourceMeter is sourcing 100V to the 2k load and subse-
quently measures 25mA. As shown, the load line for 2k intersects the 50V volt-
age source line at 25mA.
Figure 6-13B shows what happens if the resistance of the load is decreased to
800. The DUT load line for 800k intersects the current compliance limit line
placing the SourceMeter in compliance. In compliance, the SourceMeter will not
be able to source its programmed voltage (50V). For the 800k DUT, the
SourceMeter will only output 40V (at the 50mA limit).
Notice that as resistance decreases, the slope of the DUT load line increases. As
resistance approaches infinity (open output), the SourceMeter will source virtually
50V at 0mA. Conversely, as resistance increases, the slope of the DUT load line
decreases. At zero resistance (shorted output), the SourceMeter will source virtu-
Current Compliance
Limit Line
Voltage Source
Limit Line
V Source
I Measure