2-8
Connections
2-wire sensing
When using 2-wire sensing to source and/or measure voltage, the error associated with IR
drops in the test leads could be significant. The ratio between the test lead resistance and DUT
resistance determines the error that is introduced. If the error introduced by the IR drop of the
test leads is not acceptable, use 4-wire sensing.
For example, assume test lead resistance (R
L
) is 1
Ω
and the DUT resistance (R
DUT
) is
10k
Ω
. The error is calculated as follows:
Error = R
L
/ R
DUT
= 1
Ω
/ 10k
Ω
= 0.0001
= 0.01%
Notice that as the resistance of the DUT increases, the error decreases. For DUT above
1G
Ω
, guarding should also be used. See
Cable guard
.
Since current in a series circuit is the same at all points in the loop, remote sensing does not
improve I-Source or I-Measure accuracy. Thus, if sourcing current and measuring current, you
can use local sensing.
NOTE
For Measure Only (V or I) operation, 2-wire sensing must be used.
4-wire sensing
Voltage source and measure accuracy are optimized by using 4-wire sense connections.
When sourcing voltage, 4-wire 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 sensing for the following source-measure conditions:
•
The error contributed by test lead resistance for local sensing is not acceptable.
•
Optimum Ohms, V-Source, and/or V-Measure accuracy are required.
4-wire sensing specification clarifications
•
There is no hardware configurations needed to enable 4-wire sense. Simply hook up the
sense wires; otherwise, the Model 6430 will sense the voltage locally through resistors.
•
Specified accuracies for both source and measure are only achieved using 4-wire
sensing.
•
Sense wires must be no more than 10
Ω
per lead.
Summary of Contents for 6430
Page 26: ......
Page 32: ......
Page 78: ...2 14 Connections ...
Page 98: ...3 20 Basic Source Measure Operation ...
Page 138: ...5 30 Source Measure Concepts ...
Page 156: ...6 18 Range Digits Speed and Filters ...
Page 168: ...7 12 Relative and Math ...
Page 176: ...8 8 Data Store ...
Page 202: ...9 26 Sweep Operation ...
Page 248: ...11 22 Limit Testing ...
Page 310: ...16 6 SCPI Signal Oriented Measurement Commands ...
Page 418: ...17 108 SCPI Command Reference ...
Page 450: ...18 32 Performance Verification ...
Page 477: ...A Specifications ...
Page 489: ...B StatusandErrorMessages ...
Page 498: ...B 10 Status and Error Messages ...
Page 499: ...C DataFlow ...
Page 503: ...D IEEE 488BusOverview ...
Page 518: ...D 16 IEEE 488 Bus Overview ...
Page 519: ...E IEEE 488andSCPI ConformanceInformation ...
Page 523: ...F MeasurementConsiderations ...
Page 539: ...G GPIB488 1Protocol ...
Page 557: ......