Chopper-Stabilized Omnipolar Hall-Effect Switch

The A1126 integrated circuit is an omnipolar, ultrasensitive Hall-effect switch with a digital output. This device has an integrated regulator permitting operation to 24 V.

This device is especially suited for operation through extended temperature ranges, up to 150°C. Superior high-temperature performance is made possible through an Allegro patented dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature excursions, and thermal stress.

The A1126 Hall-effect switch includes the following on a single silicon chip: voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a short circuit protected open-drain output. Advanced BiCMOS wafer fabrication processing is used to take advantage of low-voltage requirements, component matching, very low input-offset errors, and small component geometries.

The omnipolar operation of the A1126 allows activation with either a north or a south polarity field of sufficient strength. In the absence of a magnetic field, the output is off. This patented magnetic-polarity-independence feature makes this device an excellent replacement for reed switches, with improved ease of manufacturing, because the A1126 does not require manufacturers to orient their magnets. These devices allow simple on/off switching in industrial, consumer, and automotive applications.

The A1126 is rated for operation between the ambient temperatures –40°C to 150°C. The available package styles provide magnetically optimized solutions for most applications. Package LH is an SOT23W, a miniature low-profile surface-mount package, while package UA is a three-lead ultramini SIP for through-hole mounting. Each package is lead (Pb) free, with 100% matte-tin-plated leadframe.