User-programmable Hall-effect switches include high-voltage transient protection for automotive applications

These new devices incorporate enhanced high-voltage transient protection: a critical feature for automotive applications that do not allow protection circuits to be located close to the sensor.

The two-wire unipolar Hall-effect switches can be trimmed by the user to optimise magnetic switch point accuracy in the application. These devices are produced by the Allegro(R) advanced BiCMOS wafer fabrication process, which implements a patented high-frequency 4-phase chopper-stabilisation 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 unipolar switches are particularly advantageous in cost-sensitive automotive applications, because they require one less wire for operation than the more traditional open-collector output switches. In addition, the system designer inherently gains diagnostic capabilities, because there is always output current flowing in one of two narrow ranges. Any current level not within these ranges indicates a fault condition.

On-chip transient protection, along with a Zener diode clamp, minimises the effects of overvoltage conditions on the supply line. This improved high-voltage transient protection allows these devices to survive the conditions specified in ISO 7637-2 with 40 V load dump for less than 0.5 seconds with minimal, and sometime no, protection from discrete components. Electrostatic discharge (ESD) protection has also been enhanced, with the devices capable of handling transients up to 8 kV Human Body Model (HBM).

The A1190, A1192 and A1193 are offered in a SOT-23W style, miniature low profile package (LH) for surface-mount applications.