Allegro MicroSystems' A1266 is a unique ultra-sensitive Hall effect switch with 3D omni-polar magnetic actuation based on vertical Hall sensor technology. It detects either magnetic pole in any orientation (X, Y, or Z). This omni-polar, omni-directional sensing capability is unique to the A1266 and makes this device ideal for applications such as:

The A1266 has no direct competition. The legacy solution has been standard micropower Hall switches or reed switches, but these solutions cannot achieve true 3D sensing and are generally less sensitive overall. An array of at least three standard Hall switches in both surface-mount and through-hole packages would be required to duplicate the functionality of the A1266.  Unlike MR devices that can sense in two directions, the A1266 has no upper limit on the applied field strength.

It is a micro-power device, making it ideal for battery operated electronics. It will operate from a 2.5 V to 5.0 V supply, consuming only 7.5 µA at 2.5 V.  Thanks to factory trimming and Allegro’s proprietary chopper stabilization/dynamic offset cancellation techniques, the electrical and magnetic characteristics of the A1266 are guaranteed across the operating voltage, and temperature ranges.

The small geometries of the BiCMOS process allow these devices to be offered in an ultra-small package suitable for most applications. Package designator “LH5” is a modified SOT23-W surface mount-package. Two pin-out options are available: one with separate open-drain outputs for each axis (X, Y, and Z) and one with a single, combined open-drain output (X+Y+Z).

The low operating supply voltage, 2.5 V to 5 V, and unique clocking algorithm assist in reducing the average operating power consumption. For example, the power requirement is less than 60 µW with a 4 V supply. On a single silicon chip, the device includes- three Hall plates, multiplexer, small-signal amplifier, chopper stabilization, Schmitt trigger, and NMOS output transistors to sink up to 2 mA. The device outputs turn on when a north/south pole of sufficient strength is applied to the sensor in any orientation. Removal of the magnetic field will turn the output off.