4-Wire Remote Sensing; Sense Mode Selection - Keithley 2651A Reference Manual

Section 2: General operation

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.
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

Sense mode selection

The sense mode can be set for 2-wire local or 4-wire remote connections.
The default sense setting is 2-wire local.
2-44
Model 2651A High Power System SourceMeter® Instrument Reference Manual
Contact check measurements
Figure 13: Model 2651A four-wire connections (remote sensing)
SENSE/GUARD
S
LO G
S LO
NOTE
(on page 2-37) for more details.
OUTPUT
LO
S
G G G HI
40V, 50A MAX.
S HI
DUT
<1 kΩ
LO
NOTE
HI
HI
2651A-901-01 Rev. A / March 2011