ATS642LSH: Two-Wire True Zero Speed Miniature Differential Peak-Detecting Gear Tooth Sensor IC with Continuous Calibration


The ATS642 is an optimized Hall IC providing a user-friendly solution for true zero-speed digital gear-tooth sensing in two-wire applications. The device consists of a single-shot molded plastic package that includes a samarium cobalt pellet, a pole piece, and a Hall effect IC that has been optimized to the magnetic circuit. This small package, with optimized two-wire leadframe, can be assembled simply and used in conjunction with a wide variety of gear shapes and sizes.

The integrated circuit incorporates a dual element Hall effect IC and signal processing that switches in response to differential magnetic signals created by ferrous gear teeth. The circuitry contains a sophisticated digital circuit to reduce magnet and system offsets, to calibrate the gain for air gap independent switchpoints, and to achieve true zero-speed operation. Signal optimization occurs at power-up through the combination of offset and gain adjust and is maintained throughout the operating time with the use of a running mode calibration. The running mode calibration allows immunity to environmental effects such as microoscillations of the target or sudden air gap changes.

The regulated current output is configured for two wire applications and the device is ideally suited for obtaining speed and duty cycle information in ABS (antilock braking systems). The 1.5 mm Hall element spacing is optimized for fine pitch gear-tooth-based configurations. The package is lead (Pb) free, with 100% matte tin leadframe plating.

For a SIP package, please see the A1642LK.

Top Features

  • Running mode calibration for continuous optimization
  • Single chip IC for high reliability
  • Internal current regulator for 2-wire operation
  • Small mechanical size (8 mm diameter × 5.5 mm depth)
  • Precise duty cycle signal over operating temperature range
  • Large operating air gaps
  • Automatic Gain Control (AGC) for air gap independent switchpoints
  • Automatic Offset Adjustment (AOA) for signal processing optimization
  • True zero-speed operation
  • Undervoltage lockout
  • Wide operating voltage range

Typical Applications

  • Anti-lock Braking Systems (ABS)
  • Electronic Stability Control (ESC)

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
ATS642LSHTN-I1-T 4-lead SIP -40°C to 150°C Yes View Data Contact your
local sales rep
Distributor Stock
ATS642LSHTN-I2-T 4-lead SIP -40°C to 150°C Yes View Data 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 ATS642 is supplied in a 4-pin SIP (suffix SH) package. The package is lead (Pb) free, with 100% matte tin lead frame plating.

SH SIP 4 pin

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