Hall-Effect Switch and Latch ICs with Integrated Self-Test Enhance ADAS Safety

Pin-compatible upgrades for legacy Hall sensors

Allegro MicroSystems, a global leader in power and sensing semiconductor technology, has announced the release of the APS11450 and APS12450, adding two Hall-effect sensor ICs to its growing portfolio of solutions for systems that require functional safety. The APS11450 is a family of unipolar switch ICs, while the APS12450 devices are bipolar latches. They are pin-compatible upgrades for existing three-wire Hall switch and latch ICs developed in accordance with ISO 26262:2011 with ASIL-B capability (pending assessment).

These magnetic sensors have  integrated self-test features that are always active in the background while the system is running, leading to very short fault detection times. This action is automatic, and the tests are executed so quickly (25µs, typical) as to be transparent to host system—even in the case of latches used in high-speed motors and encoders. The unique voltage-mode output communicates the sensor’s status (including the safe state), while remaining backward compatible with logic-level interfaces, application circuits, wiring, and firmware.

"Our challenge was to achieve the safety level required by present and future ADAS systems while being backward-compatible with our installed base of billions of Hall switches and latches," explains Jim Judkins, Product Line Director for Allegro's Digital Position Sensor ICs. "The result is the fastest diagnostics available for magnetic switches and latches and a logic-compatible output that can communicate the sensor status and support wiring open/short detection.”

Versatile in usage, the APS11450 and APS12450 were designed to enhance the performance of a variety of automotive applications and intelligent motion systems. Ideal for use in advanced driver assistance systems (ADAS) and encoders for window lifts, seat motors, seatbelt tensioners, and closure systems. These ICs are also suited for off-road vehicles, heavy equipment, human machine interfaces (HMI) and roll-over (bank angle) sensors, kickstands and driver controls in two-wheeled vehicles.

The APS11450/12450 are qualified beyond the requirements of AEC-Q100 grade 0. They were developed to ISO 26262 as a hardware safety element out of context with ASIL-B capability (pending assessment), making them suitable for automotive safety systems. The integrated safety features are also beneficial to other safety systems. Using the APS11450/12450 devices, an ASIL-B (or higher) rating can be achieved without redundant sensors, resulting in smaller, lower power, lower cost systems.

The devices are offered in two packages with magnetic characteristics that match legacy Hall sensors, making them highly flexible and easy to design with. These monolithic ICs can operate from 3.3 to 24 V and at up to 175°C junction temperature, surviving up to +35 V inputs, reverse-battery (-30V), output shorts, load-dump, and other over-voltage transients.  Allegro’s miniature LH package is a SOT-23W style package for surface-mount applications; the UA is a 3-pin, single inline package (SIP) for through-hole mounting. Both packages are lead (Pb) free, with 100% matte-tin leadframe plating.