Thursday, April 19, 2012

Bipolar Hall-effect switch offers excellent repeatability

General-purpose device offers temperature stability and stress resistance -

New from Allegro MicroSystems Europe, the A1250 is a bipolar Hall-effect switch IC incorporating a high-speed chopping circuit which cancels out offsets and dramatically improves switching repeatability through enhanced temperature stability and stress resistance.

The new device is especially suited for operation over extended temperature ranges to +150 °C. This superior high-temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally resulting from device overmoulding, temperature dependencies, and thermal stress.

The A1250 includes, on a single silicon chip, a voltage regulator, Hall voltage generator, small-signal amplifier, chopper stabilisation, Schmitt trigger, and a short-circuit-protected, open-collector output. Advanced BiCMOS wafer fabrication processing takes advantage of low-voltage requirements, component matching, very low input-offset errors, and small component geometries.

The device can act as a latch, with a south pole of sufficient strength turning the output on, and a north pole turning the output off. It can also act as a switch because there is no switch point symmetry around zero Gauss.

An on-board regulator permits operation with supply voltages from 3.0 to 24 V. The advantage of operating at 3.0 V is that the device can either be used in 3 V applications or, with additional external resistance in series with the supply pin for added protection, in applications that can supply higher voltages.

The A1250 is targeted at the automotive, industrial and consumer markets.

Two package styles provide a magnetically optimised package for most applications. Package type LH is a modified SOT-23W surface-mount package, while the UA package is a three-lead, ultra-miniature single-inline package for through-hole mounting. Each package type is available only as lead (Pb) free with a 100% matt tin-plated lead frame.

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