The MLX90217 is a self adjusting digital output rotary position gear tooth sensor designed for use in automotive camshaft sensing as well as other speed sensing applications. It is designed to be used with a bias magnet south facing the back (non-marked) side of the IC. The device has an open collector output which is short circuit protected.

The MLX90217 is a sophisticated IC featuring an on-chip 10-bit A/D Converter and logic that acts as a digital sample and hold circuit. A separate 4-bit A/D converter provides a fixed hysteresis. The 90217 does not have a chopper delay. The 90217 uses a single Hall plate which is immune to rotary alignment problems. The bias magnet can be from 50 to 400mT.

As the signal is sampled, the logic recognizes an increasing or decreasing flux density. The output will turn on (BOP) after the flux has reached its peak and decreased by an amount equal to the hysteresis. Similarly the output will turn off (BOP) after the flux has reached its minimum value and increased by an amount equal to the hysteresis.