High-voltage unipolar Hall-effect switches

Louise Smyth

Diodes Incorporated has introduced a new family of high‑performance unipolar Hall-effect switches designed for operation over a supply range of 3.0V to 28V in consumer and industrial applications.

The AH337x series of four devices features open-drain outputs in varying sensitivities from +30G to +115G while the high‑sensitivity AH3382 has an internal pull-up on its output. 

Typical applications include position and proximity sensing, open and close detection, contact-less switches, level detection, and flow meters. Markets span home appliances, consumer personal care products, office equipment and industrial position and speed measurement, such as valve position sensing.

The output of the SOT23 and SIP3 packaged versions of these devices is switched on when a magnetic south pole of sufficient strength is presented to the part-marking surface, while the SC59 packaged devices work with the opposite pole for the same effect.

These Hall-effect switches utilise a chopper-stabilised architecture with an internal bandgap referenced to achieve reliable operation over a wide -40°C to +125°C temperature range with minimal switching point drift. They offer a fast response to power-on and changes in magnetic flux density and feature a reverse blocking diode, Zener clamps on the supply and output, and output over-current limiting to provide device protection and high ESD immunity.

The AH3372 is specified for high-sensitivity requirements, with typical operate and release points of +30G Bop and +20G BRp. The medium sensitivity AH3373 offers +55G Bop and +35G BRp, while the corresponding figures for the AH3376 are +100G Bop and +85G BRp with the AH3377 delivering +115G Bop and +90G BRp. The high-sensitivity AH3782 with its internally pulled-up output has a Bop of +55G and BRp of +35G.