ATS643LSH

ATS643-DS, Rev. 1

Worcester, Massachusetts 01615-0036 (508) 853-5000

115 Northeast Cutoff, Box 15036

www.allegromicro.com

Allegro MicroSystems, Inc.

ABSOLUTE MAXIMUM RATINGS

Operating Temperature

• 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

Self-Calibrating, Zero-Speed Differential

Gear Tooth Sensor with Continuous Update

Use the following complete part numbers when ordering:

Part Number

Package

ATS643LSH-I1

4-pin plastic SIP

6.0 Low to 14.0 High mA

ATS643LSH-I2

4-pin plastic SIP

7.0 Low to 14.0 High mA

Package SH, 4-pin SIP

Features and Benefits

• Precise duty cycle accuracy through-

out 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

1. VCC

2. No connection (float or tie to VCC)

3. Test pin (float or tie to GND)

4. GND

1 2

3 4

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 compen-

sating 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 the device specifications even through large changes in air gap

or temperature.

The regulated current output is configured for two-wire operation, offering inher-

ent diagnostic information. This device is ideal for obtaining speed and duty cycle

information in gear-tooth based applications such as transmission speed sensing.