A1244: Chopper-Stabilized, Two-Wire Hall-Effect Latch

 Allegro MicroSystems recommends APS12400 for all new Automotive 2-wire Hall-Effect latch IC designs.

The A1244 is a two-wire Hall-effect latch. The devices are produced on the Allegro advanced BiCMOS wafer fabrication process, which implements a patented high-frequency, 4-phase, chopper stabilization technique. This technique achieves magnetic stability over the full operating temperature range, and eliminates offsets inherent in devices with a single Hall element that are exposed to harsh application environments.

Two-wire latches are particularly advantageous in cost-sensitive applications because they require one less wire for operation versus the more traditional open-collector output switches. Additionally, the system designer inherently gains diagnostics because there is always output current flowing, which should be in either of two narrow ranges. Any current level not within these ranges indicates a fault condition.

The Hall-effect latch will be in the high output current state in the presence of a magnetic south polarity field of sufficient magnitude and will remain in this state until a sufficient north polarity field is present.

The device is offered in two package styles. The LH is a SOT-23W style, miniature low-profile package for surface-mount applications. The UA is a 3-pin ultra-mini single inline package (SIP) for through-hole mounting. Both packages are lead (Pb) free, with 100% matte-tin leadframe plating.