Keithley 3730

Section
5: Basic Digital Multimeter (DMM) Operation Series 3700 System Switch/Multimeter
User's Manual
5
-34 Document Number: 3700S-900-
01 Rev. A / August 2007
The follow schematic provides a simplified view of the Series 3700 four-wire dry-circuit open
lead detection.
Figure 5-21: Simplified Dry-Circuit open V-clamp feedback loop schematic
Dry-clamp open lead detector (dry-circuit)
A hardware detector is used to detect an open input lead. The hardware detector uses a internal
circuit to monitor the voltage on the V
DRY-CLAMP
terminal. The circuit will abort the A/D in < 100sec
and return an overflow reading if the voltage is greater than 1V.
VMEAS open voltage (dry-circuit)
If either Input Sense HI or Sense LO V
MEAS
is outside the enclosed table voltages, the A/D will
abort in <100sec and return an overflow reading.
Range
V
MEAS
SHI or SLO High Limit Open
Lead Detection
V
MEAS
SHI or SLO Low Limit Open
Lead Detection
1
> 27mV
<
-10mV
10
-2k
> 20mV
<
-10mV
Calculated measurement open voltage (dry-circuit)
A calculated measurement, which exceed 120% of the range, will return an overflow reading.