For motor control, I need to monitor its current. Can a simple low side shunt be used for measurement, or will the offset voltage (no direct GND connection) cause problems?
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\$\begingroup\$ What current range? \$\endgroup\$– stevenvhCommented Aug 15, 2012 at 15:05
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\$\begingroup\$ re: offset voltage (no direct GND connection). How is the ground actually connected? How much offset do you expect? \$\endgroup\$– Nick AlexeevCommented Aug 16, 2012 at 2:53
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You don't say how much current the motor needs, but because it uses Hall effect instead of a shunt resistor this sensor (ACS712) has a very low internal resistance of 1.2 mΩ. That's only 12 mV drop at 10 A. Sensitivity up to 185 mV/A.
Notice also that the high current path is galvanically isolated from the signal ground in this sensor. That can solve the ground offset problem. IP- may be connected to power ground, while GND can be connected to signal ground. VIOUT will be referenced to GND.
answered Aug 15, 2012 at 15:14