User Manual

2400 Series SourceMeter
®
User’s Manual Source-Measure Concepts 6-17
Figure 6-9 shows the limit lines for the I-Source. The current source limit line rep-
resents the maximum source value possible for the presently selected current
source range. For example, if on the 100mA current source range, the current
source limit line is at 105mA. The voltage compliance limit line represents the
actual compliance that is 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 limits 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 6-9
I-Source limit lines
Voltage compliance boundaries
Where within the boundaries the SourceMeter operates depends on the load
(DUT) that is connected to its output. Figure 6-10 shows operation examples for
resistive loads that are 200Ω and 800Ω, respectively. For these examples, the
SourceMeter is programmed to source 100mA and limit 40V. (See Section 3,
“Basic source-measure procedure.”)
In Figure 6-10A, the SourceMeter is sourcing 100mA to the 200Ω load and subse-
quently measures 20V. As shown, the load line for 200Ω intersects the 100mA
current source line at 20V.
Figure 6-10B shows what happens if the resistance of the load is increased to
800Ω. The DUT load line for 800Ω intersects the voltage compliance limit line plac-
ing the SourceMeter in compliance. In compliance, the SourceMeter will not be
able to source its programmed current (100mA). For the 800Ω DUT, the SourceM-
eter will only output 50mA (at the 40V 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 40V. Conversely, as resistance decreases, the slope of the DUT load line
Voltage Compliance
Limit Line
Current Source
Limit Line
I Source
V Measure