A1667: True Zero-Speed, High Accuracy, Ring Magnet Sensor IC

A1667 Product Image


Top Features

The A1667 is a true zero-speed ring magnet sensor integrated circuit (IC) consisting of an optimized Hall IC available in two package options that provides a user-friendly solution for digital ring magnet sensing applications.

The sensor incorporates a dual element Hall IC that switches in response to differential magnetic signals created by a ring magnet. The IC contains a sophisticated compensating circuit designed to eliminate the detrimental effects of magnet and system offsets. Digital processing of the analog signal provides zero-speed performance independent of air gap and also dynamic adaptation of device performance to the typical operating conditions found in automotive applications (reduced vibration sensitivity).

High-resolution peak detecting DACs are used to set the adaptive switching thresholds of the device. Hysteresis in the thresholds reduces the negative effects of any anomalies in the magnetic signal associated with the targets used in many automotive applications.The open-drain output is configured for three-wire applications. This sensor is ideal for obtaining speed and duty cycle information using ring magnet based systems in applications such as automotive transmissions and industrial equipment.

The A1667 is available in a 4-pin SIP through-hole package (suffix K) and an 8-pin SOIC surface-mount package (suffix L). Both packages are lead (Pb) free with 100% matte-tin-plated leadframes.


  • Optimized robustness to magnetic offset variation
  • Small signal lockout for immunity against vibration
  • Tight duty cycle and timing accuracy over full operating temperature range
  • True zero-speed operation
  • Air gap independent switch points
  • Large operating air gaps achieved through use of gain adjust and offset adjust circuitry
  • Defined power-on state (POS)
  • Wide operating voltage range
  • Digital output representing target profile
  • Single chip sensing IC for high reliability
  • Small mechanical size
  • Fast startup
  • Undervoltage lockout (UVLO)

Typical Applications

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A1667LK-T 4-lead SIP -40°C to 150°C -- View Data Contact your
local sales rep
Distributor Stock
A1667LLTR-T 8-lead SOIC -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.