Allegro MicroSystems Introduces New Two-Wire ABS Wheel Speed Sensor IC With Integrated Capacitor

Allegro MicroSystems, LLC introduces a new Hall-effect based integratedcircuit (IC) that provides a user-friendly solution for true zero-speed digitalring magnet and gear tooth sensing in two-wire applications. Allegro’sA1688 wheel speed sensor IC is targeted at the automotive market andcontains industry leading features such as outstanding pitch deviationaccuracy, consistent I_CC distribution: >6 sigma, low jitter andenhanced EMC performance, and simple module assembly by utilizing a built-incap and wider lead width/spacing.

The integrated circuit incorporates a dual-element Hall-effect circuit andsignal processing that switches in response to differential magnetic signalscreated by magnetic encoders, or, when properly back-biased with a magnet, fromferromagnetic targets. The device contains a sophisticated digital circuit thatreduces magnet and system offsets, calibrates the gain for air gap independentswitch points, and provides true zero-speed operation. Signal optimizationoccurs at power-up through the combination of offset and gain-adjust and ismaintained throughout operation with the use of a running-mode calibrationscheme. Running-mode calibration provides immunity from environmental effectssuch as micro-oscillations of the sensed target or sudden air gap changes.

The regulated current output is configured for two-wire interface circuitryand is ideally suited for obtaining speed information in wheel speedapplications. The Hall element spacing is optimized for high resolution, smalldiameter targets. The A1688 is offered in the UB package, which integrates theIC and a high temperature ceramic capacitor in a single overmolded SIP package.The package is lead (Pb) free, with 100% matte-tin leadframe plating. Theintegrated capacitor provides enhanced EMC performance with reduced externalcomponents.  

Pricing for 1,000 pieces is as follows:

• A1688LUBTN-L-T:      $1.02
• A1688LUBTN-H-T:      $1.02

About Allegro

Allegro MicroSystems, LLC is a leader in developing, manufacturing andmarketing high-

performance semiconductors. Allegro’s innovative solutions serve high-growth

applications within the automotive market, with additional focus on officeautomation,

industrial, and consumer/communications solutions. Allegro is headquarteredin

Worcester, Massachusetts (USA) with design, applications, and salessupport centers

located worldwide. Further information aboutAllegro can be found at www.allegromicro.com.