I have an application where the maximum DC current is 160A. However in reality the actual current flow never exceeds 40A. I want to measure the current with an ADC (like one found on the Arduino or a higher resolution ~16 bit ADC). I originally wanted to use a hall effect sensor, specifically the ACS770ECB-200U-PFF-T.
Typically, my application uses around 5A. I am aiming for a .01A resolution. I looked at the sensitivity (mv/A) and thought I could get a higher resolution ADC to get more accurate current sensing. However when I looked at the data sheet it said the following:
The noise floor is derived from the thermal and shot noise observed in Hall elements. Dividing the noise (mV) by the sensitivity (mV/A) provides the smallest current that the device is able to resolve.
This means that with the typical noise found in the datasheet of 6mv, and the sensitivity being 20mv/A, I would only get a .3A current resolution.
Am I correct? How can I achieve a >.01A current resolution? I can use a shunt resistor if I have to, or a 50A current sensor instead. But the 50U version gives 20mv of typical noise and 80mv/A sensitivity, giving a 0.25A current resolution.
Also, is this noise the ripple voltage of the power supply for the current sensor?
I'm also a little confused as to what the datasheet means by bandwidth
120 kHz typical bandwidth
As I don't see what is oscillating.
Thank you for your time!