Hall-effect device offers new sensing options

November 04, 2015 // By Christoph Hammerschmidt
The A1262 from Allegro MicroSystems Europe is a dual-channel Hall-effect latch that enables two-dimensional (2D) sensing via a combination of vertical and planar Hall elements. This combination enables designers to achieve sensor configurations hitherto not feasible.

The quadrature outputs of the A1262 allow rotation direction and position to be determined in applications such as sensing a rotating ring-magnet target. The 2D operation of the combined planar and vertical Hall elements allows users to achieve an ideal 90° of phase separation between channels which is also inherently independent of ring magnet geometry and pole pitch.

Using the A1262, system designers can achieve new mechanical configurations which would not be feasible with traditional planar Hall sensors, including replacing pairs of through-hole single-inline packaged devices with a single, tiny surface-mount SOT23 IC, saving space and cost.

The A1262 is targeted at motor commutation and rotary position sensing applications in the automotive, industrial and consumer markets. Typical uses include window blinds, garage door openers, scroll wheels, power window lifts, white goods, and controls for sunroof, sliding door, car-boot and tailgate motors in the automotive sector.

The sensor IC is available in two options that allow flexibility in the magnetic design of end-user systems. Both options feature a planar Hall element that is sensitive to magnetic fields perpendicular to the face of the package (the Z direction). The other signal channel comes from a vertical Hall element that is sensitive in either the X or Y direction.

The Y option features a vertical Hall plate that is sensitive to magnetic fields parallel with the face of the package across the leaded edges of the package, while the X option features a vertical Hall plate that is sensitive to magnetic fields parallel with the face of the package across the leadless edges of the package, resulting in a lower total effective air gap than can be achieved with competing solutions.

Each device includes, on a single silicon chip, two Hall plates (one planar and one vertical), a multiplexer, a small-signal amplifier, chopper stabilisation, a Schmitt trigger circuit, and two short-circuit protected NMOS output transistors to sink up to 20 mA. The on-board