Are hall effect sensors ratiometric?
Most are ratiometric .So under normal applications you want to keep the supply volts constant .Example if 400 amps means 1.5 volts output with a supply volts of 5VDC .If you keep 400 Amps but move the 5VDC to say 5.5VDC your expected output will be 1.65VDC and if you reduced the supply to 4.5VDC then expect a 1.35VDC output .I have discussed small supply volts variations .Large variations are limited by max ratings and the min volts for the internal opamp to work .