The SS817 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 bias magnet can be from 50 to 400 mT. The device has an open collector output which is short circuit protected.

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