2400 Series SourceMeter
®
User’s Manual Connections 2-9
Ohms guard
Use the guarded ohms connection schemes shown in Figure 2-5 for the following source-
measure operation:
• In-circuit resistance measurements on the DUT where other parasitic leakage
devices are present.
Note that ohms guard must be selected for this connection scheme. Ohms guard is not
available for the 1A range (source or measure). See “Guard selection,” page 2-12, to select
ohms guard and Section 4, “6-wire ohms measurements.”
Figure 2-5 shows how to make connections to measure the resistance of a single resistor
(DUT) in a resistor network. See Section 6, “Guard,” for more information on guarded
ohms measurements.
The basic connection scheme for guarded ohms measurements is shown in Figure 2-5A. If
the guard resistance path (R
G)
is
<1kΩ, IR drop in the GUARD test lead could be high
enough that the guard voltage at the resistor network is significantly less than the output
voltage at the DUT. This results in leakage current and will corrupt the measurement. To
cancel the effect of IR drop in the GUARD test lead, connect GUARD SENSE to the resis-
tor network as shown in Figure 2-5B. Guard sense ensures that the guard voltage at the
resistor network is the same as the output voltage at the DUT.
Note that if the DUT is <1kΩ, you should use the 4-wire measurement method (remote
sensing) by connecting SENSE HI and LO to the DUT and enabling remote sense (Figure
2-5C).
NOTE Guard current (I
G
) must never exceed 50mA. If it does, guard voltage will
become less than the output voltage and corrupt the measurement.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
Need help?
General
