Three-Wire Differential Sensor Thwarts EMI

Allegro’s ATS668 optimized Hall-effect three-wire differential speed sensor integrated circuit (IC) and permanent magnet pellet combination integrates EMC protection components for true zero-speed digital gear tooth sensing.

It is offered in a small single over-mold package that can be easily assembled and used in conjunction with a wide variety of gear tooth sensing applications. Designed for automotive transmission systems, the device incorporates a dual element Hall IC that switches in response to differential magnetic signals created by a ferromagnetic target. The IC contains a sophisticated compensating circuit designed to eliminate the detrimental effects of magnet and system offsets. Digital processing of the analog signal provides zero-speed performance independent of air gap and dynamic adaptation of device performance to the typical operating conditions found in automotive applications, i.e., vibration and runout.