Here are few issues which you may experience when using AMR current sensors. The biggest challenge is that they seem to be so perfect in static conditions but when under heavy load many errors may add to real signal which typically leads to complete malfunction or worse sporadic malfunction/destruction of the whole device. See below my experience from another project.
Signal Id offset error(Id current - grey - signal shifted in amplitudes)
Id current saturation error
Id current seemingly OK after a small piece of soft magnetic steel has been placed on top of the integrated circuit. But check the -2 A offset error when no current is which is caused by the residual magnetization of this new shield.
Yellow: voltage across 2.2 Ohm resistor, maximum is 22V (current = voltage / resistance in any given time) Blue: current sensor output voltage.
Switched mode power supply with 22V on the output was shorted via 2R2 resistor. Current rises to 5 A immediately but after that the power supply load response takes 2us to regulate it to desired voltage and hence 10 A current. Sensor output lags approximately for 200 ns and rises with maximum slope 10 A/us untill it catches up with the output. This data is not ideal for bandwidth measurement but it confirms the functionality of the sensor. Also for sure there is no need to not believe to the IC datasheet.
kevarek
