Programmable Hall-effect switch with advanced programming algorithm

December 11, 2012 // By Christoph Hammerschmidt
The A1128 from Allegro MicroSystems Europe is a field-programmable unipolar Hall-effect switch designed for use in high-temperature automotive and industrial applications, particularly those involving proximity sensing with ferromagnetic targets.

The new device uses a chopper-stabilisation technique to eliminate the offset inherent in single-element devices, and incorporates an advanced programming algorithm to simplify the customer's end-of-line process. It also has a high programming resolution for tighter magnetic switch points.

External programming is used to set the magnetic operating point while the hysteresis remains fixed. This advanced feature allows optimisation of the sensor IC switch point, and can drastically reduce the effects of mechanical placement tolerances found in end-user production environments. Other programmable parameters include output polarity and output fall time for reduced EMI in automotive applications.

The proprietary dynamic offset cancellation technique, with an internal high-frequency clock, reduces the residual offset voltage, which is normally caused by device overmoulding, temperature dependencies, and thermal stress. Having the Hall element and amplifier on a single chip minimises many problems normally associated with low-level analogue signals.

The new device includes an on-board voltage regulator for 3 to 24 V operation, and features on-chip protection against supply transients, output short-circuits, and reverse battery condition.

The A1128 is offered in the UA three-lead ultra-miniature single-in-line package for through-hole mounting. This package is lead (Pb) free, with 100% matt tin-plated lead frames.