multicomp pro MP730889 - Measurement Tutorial; Loading Errors (DC Voltage)

Multicomp-pro
33
4. Measurement Tutorial
Loading Errors (DC Voltage)
Measurement loading errors occur when the resistance of the DUT(Device-Under-Test) is
an appreciable percentage of the multimeter's input resistance, as shown below.
V
s
= ideal DUT voltage
R
s
= DUT source resistance
R
i
= multimeter input resistance
Error
is
s
100 R
()
RR
%
×
=
+
For the mV range, input impedance≥ 5 MΩ. For other range, input impedance≥10 MΩ.
HI
LO
Ideal
Meter
R
s
V
s
R
i