How small of a current can the ACS754 resolve?
Without filtering, the ACS754’s 50 A version can resolve a change in current level of ≈2.5% of full scale, at 25ºC, through its primary conductor leads. The 200A version can resolve ≈1.6%. At these levels, the amount of magnetic field coupled into the linear Hall Effect IC is just above its noise floor. However, depending on the temperature, 0-ampere offset error, and the dc current level, the percentage error of the current device output will often be greater than this minimum resolvable current. Resolution can be improved by filtering the output of the ACS754. Up to a threshold value, this can be done without limiting the response time. See the application note “Managing Noise Levels in the ACS75X Current Sensor ICs,” at www.allegromicro.com/techpub2/an/acs75xan1.pdf.
