Unipolar Hall-effect switches for 3V to 28V operation

July 20, 2016 // By Graham Prophet
These unipolar Hall-effect switches are designed for operation over a supply range of 3.0V to 28V in consumer and industrial applications. Diodes Inc’s AH337x series of four devices features open-drain outputs in varying sensitivities from +30G (Gauss) 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 utilize a chopper-stabilized architecture with an internal bandgap reference to achieve reliable operation over a -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.


In 3-pin SOT23 and SIP-3 packages, and also an SC59 package that provides the option of switching with a magnetic north pole, the AH3372, AH3373, AH3376, AH3377 and AH3782 are priced from $0.18 (1000).


Diodes; www.diodes.com