Description

The ATS643 is an optimized combination of integrated circuit

and magnet 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 magnet, 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 easily assembled and used in conjunction with

a wide variety of gear shapes and sizes.

The integrated circuit incorporates a dual element Hall-effect

sensor with signal processing circuitry that switches in response

to differential magnetic signals created by rotating ferrous

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 fine-

tune the switchpoints while in running mode, maintaining

ATS643-DS, Rev. 2

Features and Benefits

▪ Fully-optimized differential digital gear tooth sensor

▪ Single chip-IC for high reliability

▪ Internal current regulator for 2-wire operation

▪ Small mechanical size (8 mm diameter x 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

Self-Calibrating, Zero-Speed Differential

Gear Tooth Sensor with Continuous Update

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Functional Block Diagram

Not to scale

Packages: 4 pin SIP (suffix SH)

ATS643LSH

Hall AMP

AGC

Threshold

Logic

ThresholdP

ThresholdN

PDAC

Internal

Regulator

VCC (Pin 1)

NDAC

GND (Pin 4)

Reference

Generator

and Updates

Offset Adjust

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