Two-Wire, Zero-Speed Differential Gear Tooth Sensor IC


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Top Features


The ATS684LSN gear tooth sensor is an optimized, industry-proven, Hall effect integrated circuit (IC), rare-earth pellet, and high temperature ceramic capacitor in a single over molded package. The integrated capacitor reduces the need for external EMI protection. The Hall-effect IC is a dual element differential sensor design capable of providing stable, signal perturbation-immune, output performance for speed sensing applications.

The back-bias magnet creates a differential magnetic signal in the presence of a rotating ferromagnetic target. This fully integrated speed sensor solution eliminates the need for additional manufacturing steps throughout the supply chain, simplifying the overall system design.

The single overmold design integrates the key operating components to reduce mechanical tolerances and achieve optimal operating performance every time, whether it’s an industrial gear speed sensor or an automotive transmission sensor. Built-in test capability and an automotive-grade semiconductor process ensures the quality and reliability that automotive companies demand in their applications (i.e. transmission speed sensors). The advanced algorithms and two-wire regulated current output provide an ideal solution for obtaining edge and duty cycle information in gear-tooth-based applications such as transmission speed.

The ATS684 is provided in a lead (Pb) free 2-pin back-biased SIP package (suffix SN) with tin leadframe plating.

Featured Video:

Differential Speed Sensor System Solutions

Seth Prentice, Strategic Marketing Manager for Allegro MicroSystems Speed Sensor IC group, discusses IC solutions for designing speed sensing applications including automotive transmissions, washing machine drum speeds, and fork lift positioning requiring reliable consistent output signals. Watch Video

  • Integrated package solution offers EMI protection, industry-proven IC, and back-bias magnet in a single overmolded, user-friendly package
  •  Advanced algorithm design provides immunity to signal perturbations from vibration, ferrous debris, target eccentricities, and harsh automotive operating conditions
  • Adaptive threshold sensing optimizes output performance on a wide range of target types
  • Integrated Scan, Iddq, and Built-In Self-Test capabilities on an automotive-grade semiconductor process provide dependability essential in the safety-conscious automotive market

The ATS684 is available in a lead (Pb) free 2-pin (suffix SN) SIP package with a 100% matte tin plated leadframe. 

SN Package Documentation

Part Number Specifications and Availability

Documentation and Resources


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Documents Found: 32
Document Type Document Name
Application Note
Transmission Gear Tooth Sensing
Application Note
Fundamental Properties of Speed Sensors