Hall-effect sensor targets tachometer applications

April 02, 2014 // By Graham Prophet
With one of its target functions being motorcycle tachometers, this true zero-speed differential peak-detecting sensor IC incorporates continuous running-mode calibration

The A1468 from Allegro MicroSystems Europe is a true zero-speed differential peak-detecting Hall-effect sensor IC that is optimised for use in automotive speed, timing and duty-cycle sensing: particularly in motorcycle tachometer applications.

The new device is suited to digital ring-magnet sensing or, when coupled with a magnet, ferromagnetic target sensing in three-wire applications. The small device package can be readily incorporated into designs using a wide variety of target shapes and sizes.

The A1468 incorporates dual Hall-effect sensing elements with 2.2 mm spacing and signal processing circuitry that switches in response to differential magnetic signals created by ring magnet poles. The device contains a digital circuit which reduces system offsets, calibrates the gain for airgap–independent switch points, and achieves true zero-speed operation through peak detecting algorithms.

Signal optimisation occurs at power-on through the combination of offset and gain adjust, and is maintained during operation by continuous running-mode calibration which provides immunity to environmental effects such as micro-oscillations of the target or sudden airgap changes.

The Allegro A1468LK-T is available in a 4-pin through-hole SIP package (suffix K).

Allegro MicroSystems; www.allegromicro.com