Allegro MicroSystems, LLC Announces Unique New 2D Speed And Direction Sensor IC Using Vertical And Planar Hall Elements

November 03, 2015
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Quadrature Signals Independent of Ring Magnet Geometry

Worcester, MA – Allegro MicroSystems, LLC announces the release of a unique dual-channel Hall-effect latch featuring two-dimensional (2D) sensing via a combination of vertical Hall and planar Hall elements. The quadrature outputs of the A1262 allow rotation direction and position to be determined, such as when sensing a rotating ring-magnet target. The unique 2D operation of the combined planar and vertical Hall elements allows the end user to achieve an ideal 90° of phase separation between channels that is inherently independent of ring magnet geometry (pole pitch). This enables system designers to achieve new mechanical configurations not feasible with traditional planar Hall sensors, including replacing through-hole SIP devices with tiny surface-mount SOT23 ICs, saving space and cost. This new device is targeted at applications in the automotive, industrial, and consumer markets such as motor commutation and rotary position sensing, e.g., window blinds, garage door openers, scroll wheels, power window lifts, sunroof/sliding door/trunk/tailgate motors, white goods, etc.

Allegro’s A1262 is available in two options that allow flexibility in end-system magnetic design. Both options feature a planar Hall element that is sensitive to magnetic fields perpendicular to the face of the package (Z). The other 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. 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 lower total effective air gap than can be achieved with competing solutions.

On a single silicon chip, the device includes: two Hall plates (one planar and one vertical), a multiplexer, a small-signal amplifier, chopper stabilization, a Schmitt trigger, and two short-circuit-protected NMOS output transistors to sink up to 20 mA. The on-board regulator permits operation with supply voltages of 4 to 24 V and adds EMC robustness such as greater protection against high voltage transient events. The A1262 is qualified to AEC-Q100 standards and includes Zener clamps, output short-circuit protection, and reverse-battery protection. Superior high-temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress.

The device is highly sensitive (BOP = 17 G typical) and its magnetic operating characteristics are specified across the operating voltage and temperature ranges. Package designator “LH5” is a modified SOT23-W surface-mount package, magnetically optimized for a variety of orientations. This package is lead (Pb) free, with 100% matte-tin leadframe plating.