How small of a current can the ACS758 resolve?
The current resolution of the ACS758 family of current sensor ICs is limited by the noise floor of the device output signal. For example, the ACS758-050 version can resolve a change in current level of about 250 mA, at 25°C, through its primary conductor leads. The 200 A version can resolve approximately 380 mA. At these levels, the amount of magnetic field coupled into the linear Hall-effect IC is just above its noise floor. Resolution can be improved significantly by filtering the output of the ACS758 for applications requiring lower bandwidth. Table 1 lists the noise levels, and hence current resolutions, at various bandwidths. Filtering was accomplished with a simple, first order RC filter. Note the related graphs, figures 2 through 5, which provide a better understanding of the device output resolution that can be achieved through filtering.
