User manual

F-2 Contact Check Function 2400 Series SourceMeter
®
User’s Manual
Introduction
This appendix contains information on the contact check function available with
the Models 2400-C, 2410-C, 2420-C, 2425-C, 2430-C, and 2440-C SourceMe-
ters.
Overview
Description
The contact check function prevents measurements that may be in error due to
excessive resistance in the force or sense leads when making remotely sensed
(Kelvin) measurements. There are many potential sources for this resistance,
including poor contact at the DUT, failing relay contacts on a switching card, and
wires that are too long or thin. This is shown schematically in Figure F-1, where
R
C
is the resistance of the mechanical contact at the DUT, and R
S
is the series
resistance of relays and cables. The contact check process performs a differential
resistance measurement between each source lead and it's corresponding sense
(Kelvin) lead. The resultant resistance is then compared to the programmed limit
and a pass or fail result is determined. This process takes place in as short as
350uS and delivers no energy to the device under test.