Gear-tooth sensor aims for automotive applications

The ATS645 is a differential Hall-effect gear-tooth sensor that can sense very small symmetrical tooth geometries with high reliability in applications such as automotive ABS and transmission sytems.

The ATS645 is a differential Hall-effect gear-tooth sensor that is able to sense very small symmetrical tooth geometries with high reliability in applications such as automotive ABS and transmission systems.

This 'next generation' digital gear-tooth sensor combines a miniature two-wire back-biased package, peak detecting algorithms and automatic gain control to provide a user-friendly single-chip solution for true zero-speed gear-tooth sensing.

The ATS645 is based on an optimised configuration of a single-chip differential Hall-effect sensor IC with patented signal-processing circuitry, a samarium cobalt magnet, and a flat ferrous pole piece.

The two Hall elements are spaced 1.5mm apart, allowing the device to sense small gear-tooth geometries.

In operation, the device measures the magnetic gradient as the ferrous gear tooth passes, converts the signal to an analogue voltage, and processes it to provide a digital output signal.

The circuitry contains a sophisticated digital circuit to eliminate magnet and system offsets and to achieve true zero-speed operation.

This device makes speed sensing using a ferrous target with symmetrical teeth very simple, and removes the need for a third sense wire.

The Hall-IC/magnet configuration is integrally moulded into a plastic subassembly (package style SH) that has been optimised for size and ease of assembly.

The package measures only 8.0mm diameter by 5.5mm in length, and can be used in conjunction with a wide variety of gear shapes and sizes.

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