A chopped Hall sensor with programmable "true power-on" function

This work presents a Hall sensor for camshaft applications including a programmable "true power-on" switching level effective after the power-up phase. The proposed chopping techniques and self-compensation methods for temperature drifts and technology spreads improve the magnetic offsets from 5-10 mT to below 200 μT in a bandwidth of 30 kHz and stabilize the spread of the magnetic switching points from 20% to <2% in a temperature range from -40°C to 175°C. Internal ADC, DAC and digital signal processing provide an enhanced self-calibration algorithm to adjust the magnetic switching point and to improve the phase error to <0.5°. Surface micro-machined cavity fuses offer an end-of-line calibration for the customer with reliable function higher than 195°C.