Hall-effect sensor ICs enhance ADAS safety
Two Hall-effect sensor ICs have been announced by Allegro Microsystems for systems that require functional safety.
The APS11450 is a family of unipolar switch ICs and 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).
The magnetic sensors have integrated self-test features that are always active in the background while the system is running. This leads to very short fault detection times, says Allegro. The action is automatic, and the tests are executed, typically in 25 micro seconds, making them transparent to the host system. Allegro points out this is even in latches used in high-speed motors and encoders. The 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.
The APS11450 and APS12450 are designed to enhance automotive applications and intelligent motion systems, such as advanced driver assistance systems (ADAS) and encoders for windows, seat motors, seatbelt tensioners, and closure systems. The 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 and APS12450 are qualified beyond the requirements of AEC-Q100 grade 0, says Allegro. They were developed to ISO 26262 as a hardware safety element with ASIL-B capability (pending assessment) for automotive safety systems.
When using the APS11450 or APS12450 devices, developers can achieve an ASIL-B (or higher) rating without redundant sensors, for smaller, less expensive systems.
Two package choices are available, with magnetic characteristics that match legacy Hall sensors. The monolithic ICs operate from 3.3 to 24V and at up to 175 degrees C junction temperature, surviving up to +35V 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 and the UA version is a three-pin, single inline package (SIP) for through-hole mounting. Both packages are lead (Pb) -free, with 100 per cent matt-tin leadframe plating.