Keithley 3720-ST User Manual

Series 3700A System Switch/Multimeter Reference Manual Section 8: Theory of operation
3700AS-901-01 Rev. D/June 2018 8-15
ISOUR open voltage
1 Ω through 1 MΩ ranges: A hardware detector detects an open input lead. The hardware detector
uses a comparator circuit to monitor the voltage on the ohm I
SOUR
V
OPEN-HI-LEAD
terminal.
• For the lower ohms ranges (1 Ω, 10 Ω, and 10 kΩ), open circuit voltage on the ohm I
SOUR VOPEN-HI-
LEAD
terminal is more than 7.1 V.
• For the higher ohms ranges (100 kΩ through 1 MΩ), open circuit voltage on the ohm I
SOUR VOPEN-HI-
LEAD
terminal is more than 12.8 V.
When an input lead (HI or LO) is open, as shown, voltage rises to the open-circuit level, then the A/D
will abort in less than 100 µsec and the "Overflow" message is displayed.
VMEAS open voltage
If either Input Sense HI or Sense LO V
MEAS
is outside the enclosed table voltages, the A/D stops in
less than 100 µs and returns 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 Ω to100 Ω
> 128 mV
< –10 mV
1 kΩ to 100 kΩ
> 1.28 V
< –100 mV
1 MΩ
> 12.8 V
< –1.0 V
Calculated measurement open voltage
A calculated measurement that exceeds 120 percent of the range returns an overflow reading.
Figure 115: 4-wire open detector with Series 3700A card

Keithley 3720-ST Specifications

General

Brand	Keithley
Model	3720-ST
Category	Multimeter
Language	English