ATS643LSH: Self-Calibrating Zero-Speed Differential Gear Tooth Sensor ICs with Continuous Update


DISCONTINUED PART: This part is no longer in production. Samples are no longer available.

Date of status change: August 1, 2011.

Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the ATS685.

The ATS643 is an optimized combination of integrated circuit and rare-earth pellet that provides a manufacturer-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 and the automotive environment. This small package 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 with signal processing circuitry that switches in response to differential magnetic signals created by rotating ferromagnetic targets. The device contains a sophisticated compensating circuit to eliminate magnet and system offsets immediately at power-on. Digital tracking of the analog signal is used to achieve true zero-speed operation, while also setting the device switchpoints. The resulting switchpoints are air gap independent, greatly improving output and duty cycle accuracy. The device also uses a continuous update algorithm to finetune the switchpoints while in running mode, maintaining the device specifications even through large changes in air gap or temperature.

The regulated current output is configured for two-wire operation, offering inherent diagnostic information. This device is ideal for obtaining speed and duty cycle information in gear-tooth based applications such as transmission speed sensing.

Top Features

  • Fully-optimized differential digital gear tooth sensor IC
  • Single chip-IC for high reliability
  • Internal current regulator for 2-wire operation
  • Small mechanical size (8 mm diameter × 5.5 mm depth)
  • Switchpoints air gap independent
  • Digital output representing gear profile
  • Precise duty cycle accuracy throughout temperature range
  • Large operating air gaps
  • <2 ms power-on time
  • AGC and reference adjust circuit
  • True zero-speed operation
  • Undervoltage lockout
  • Wide operating voltage range
  • Defined power-on state

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
ATS643LSHTN-I1-T 4-lead SIP -40°C to 150°C Yes View Data Last time buy Contact your
local sales rep
Distributor Stock
ATS643LSHTN-I2-T 4-lead SIP -40°C to 150°C Yes View Data Last time buy 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.


4 pin SIP (suffix SH)

SH SIP 4 pin