3-26
Basic DMM Operation
Model 2701 User’s Manual
Constant-current source method
For the 100
Ω
to 1M
Ω
ranges, the Model 2701 uses the constant-current method to measure
resistance. The Model 2701 sources a constant current (I
SOUR
) to the DUT and measures
the voltage (V
MEAS
). Resistance (R
DUT
) is then calculated (and displayed) using the
known current and measured voltage (R
DUT
= V
MEAS
/I
SOUR
).
The constant-current method is shown in Figure 3-10. The test current sourced to the DUT
depends on the selected measurement range. For example, for the 100
Ω
range, the test cur-
rent is 1mA. Since the voltmeter of the Model 2701 has very high input impedance
(>10G
Ω
), virtually all the test current (1mA) flows through the DUT.
For DUT
≤
1k
Ω
, 4-wire ohms measurements should be used as shown in Figure 3-10B. The
voltage is measured at the DUT. This eliminates IR drop in the test leads, which could be
significant when measuring low ohm DUT.
2701-900-01.book Page 26 Wednesday, August 3, 2011 9:43 AM
Summary of Contents for 2701
Page 344: ...12 CommonCommands 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 366: ...15 SCPIReferenceTables 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 393: ...A Specifications 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 399: ...B Model7700ConnectionGuide 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 410: ...C StatusandErrorMessages 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 417: ...D SignalProcessing SequenceandDataFlow 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 430: ...E MeasurementConsiderations 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 450: ...G KE2700InstrumentDriver Examples 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...