2600S-901-01 Rev. C / January 2008
Return to
8-15
Series 2600 System SourceMeter® Instruments Reference Manual
Section 8: Source-Measure Concepts
Load considerations
The boundaries the SourceMeter operates in depends on the load (DUT) that is connected to the
output.
shows operation examples for resistive loads that are 2k
Ω
and 800
Ω
,
respectively. For these examples, the SourceMeter is programmed to source 10V and limit 10mA.
A, the SourceMeter is sourcing 10V to the 2k
Ω
load and subsequently measures
5mA. As shown, the load line for 2k
Ω
intersects the 10V voltage source line at 5mA.
B shows what happens if the resistance of the load is decreased to 800
Ω
. The DUT
load line for 800
Ω
intersects the current compliance limit line placing the SourceMeter in
compliance. In compliance, the SourceMeter will not be able to source its programmed voltage
(10V). For the 800
Ω
DUT, the SourceMeter will only output 8V (at the 10mA 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 10V at 0mA. Conversely,
as resistance increases, the slope of the DUT load line decreases. At zero resistance (shorted
output), the SourceMeter will source virtually 0V at 10mA.
Regardless of the load, current will never exceed the programmed compliance of 10mA.
Figure 8-10
Current Limit
Load Line
Voltage Source
Load Line
V-Source (V
S
)
I-Meter
(I
M
)
5mA
10mA
10V
2k
W
DUT Load Line (R)
I
M
= V
S
/ R
V
S
= I
M
R
= 10V/2k
W
= 5mA
A) Normal V-source operation
Current
Limit
Load Line
Operating
Point
Voltage
Source
I-Meter
(I
M
)
10mA
10V
= (10mA) (800
W
)
= 8V
B) V-Source in compliance
8V
800
W
DUT Load Line (R)
V-Source (V
S
)
Operating
Point
V-Source operating examples
