Section 2: General operation Model 2651A High Power System SourceMeter® Instrument Reference Manual
2-44 2651A-901-01 Rev. A / March 2011
4-wire remote sensing
When sourcing and/or measuring voltage in a low-impedance test circuit (see the figure below), there
can be errors associated with IR drops in the test leads. Voltage source and measure accuracy are
optimized by using 4-wire remote sense connections. When sourcing voltage, 4-wire remote sensing
ensures that the programmed voltage is delivered to the DUT. When measuring voltage, only the
voltage drop across the DUT is measured.
Use 4-wire remote sensing for the following source-measure conditions:
• Sourcing and/or measuring voltage in low impedance (<1 kΩ) test circuits.
• Enforce voltage compliance limit directly at the DUT.
NOTE
When sourcing voltage in remote sense, make sure the sense leads are connected to the DUT. If a
sense lead becomes disconnected, an erroneous voltage will be sensed, and the Model 2651A will
increase the output voltage to compensate. You can use contact check to verify that the sense leads
are connected. Refer to Contact check measurements (on page 2-37) for more details.
Figure 13: Model 2651A four-wire connections (remote sensing)
LO
DUT
<1 kΩ
S LO
GGGG
S
LO
SENSE/GUARD
S
HI
LO HI
OUTPUT
40V, 50A MAX.
HI
S HI
Sense mode selection
The sense mode can be set for 2-wire local or 4-wire remote connections.
NOTE
The default sense setting is 2-wire local.
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