C h a p t e r 3
Current sense resistors – A quick
overview
Current sense resistors are placed in series with a
load such that the main current flow through the
load also goes through the resistor. The voltage
drop generated across the resistor (which has a
known value) is proportional to the current flowing
through it. This voltage drop across the resistor
can be measured by various amplifier options, such
as operational, differential, and instrumentation
amplifiers. The four-wire Kelvin principle can be used
to mitigate the negative effect of contact resistance
such as that from solder pads or traces on the
printed circuit board (PCB).
CURRENT
MEASUREMENT
The most significant change in current
measurement is happening in the
automotive industry, especially now that
hybrids and electric vehicles are becoming
commonplace. Previously we didn't need
to measure the current consumption from
the battery, but now, with the battery
being the primary power source, current
measurement of the battery becomes
essential."
Hao Jie Chan
Senior Analog Hardware Engineer, NI (National Instruments)
16
Passives and Their Emerging Applications
