ATS651: Two-Wire Self-Calibrating Differential Speed and Direction Sensor IC with Vibration Immunity


This part is in production but has been determined to be NOT FOR NEW DESIGN. Sale of this part is currently restricted to existing customer programs already using the part. The part should not be purchased for new programs or designed into new applications. Samples are no longer available. Date of status change: December 5, 2016.

Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the ATS692LSHTN-RSNBL-T.

The ATS651LSH is a mechatronics component with an integrated Hall-effect sensor IC and rare-earth pellet, providing an easy-to-use solution for speed and direction sensing applications. The solid thermoset molded plastic package contains a samarium cobalt pellet and a Hall-effect IC optimized to the magnetic circuit. This device has been designed specifically for high reliability in the harsh automotive environment. The IC employs patented algorithms for the special operational requirements of transmission applications.

This two-wire device communicates the speed and direction of a ferromagnetic target via a pulse width modulation (PWM) output protocol. The innovative dual differential detector scheme uses three Hall elements and two separate signal processing channels. This provides greater reliability than conventional designs. Because only one of the channels controls switching, the same edge of each tooth is used for determining output signals, in both forward and reverse target rotation, with direction information available on the first magnetic edge after a direction change.

The ATS651LSH is particularly adept at handling vibration without sacrificing maximum air gap capability or creating an erroneous “direction” pulse. Even the higher angular vibration caused by engine cranking is completely rejected by the device. The advanced vibration detection algorithms systematically calibrate the IC on the true rotation signals from the first three and a half teeth, not on vibration, thus always guaranteeing an accurate signal in running mode.

Patented running mode algorithms also protect against air gap changes, whether or not the target is in motion. Advanced signal processing and innovative algorithms make the ATS651LSH an ideal solution for a wide range of speed and direction sensing needs.

The device package is lead (Pb) free, with 100% matte tin plated leadframe.

Some restrictions may apply to certain types of sales. Contact factory for details.

Top Features

  • Rotational direction detection
  • Fully optimized digital differential gear-tooth sensor IC
  • Single-chip sensing IC for high reliability
  • Small mechanical size (8 mm diameter × 5.5 mm vertical, flat-to-flat)
  • Internal current regulator for 2-wire operation
  • Automatic Gain Control (AGC) and reference adjust circuit
  • 3-bit factory trimmed for tight pulse width accuracy
  • True zero-speed operation
  • Wide operating voltage range
  • Undervoltage lockout
  • Defined power-on state
  • ESD and reverse polarity protection

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
ATS651LSHTN-T 4-lead SIP -40°C to 150°C Yes View Data Not for new design Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.


The device package is lead (Pb) free, with 100% matte tin plated leadframe.

SH SIP 4 pin