Features and Benefits

• Fully optimized differential digital gear tooth sensor IC

• Running Mode Lockout

• Unique algorithms for increased vibration immunity

• AGC and reference adjust circuit

• Air gap independent switchpoints

• Digital output representing gear profile

• Precise duty cycle throughout operating temperature range

• Large operating air gap range

• Short power-on time

• True zero-speed operation

• Undervoltage lockout (UVLO)

• Wide operating voltage range

• Internal current regulator for two-wire operation

• Single-chip sensing IC for high reliability

• Robust test coverage capability using Scan Path

and IDDQ measurement

Description

TheATS685LSH is an optimized Hall-effect sensing integrated

circuit and rare-earth pellet combination that provides a

user-friendly solution for true zero-speed digital gear-tooth

sensing in two-wire applications. The sensor IC 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 can be

easily assembled and used in conjunction with a wide variety

of gear shapes and sizes.

The single integrated circuit incorporates a dual element

Hall-effect sensor IC and signal processing circuitry that

switches in response to differential magnetic signals created

by ferromagnetic targets. The device contains a sophisticated

compensating circuit to eliminate magnetic and system offsets.

Digital tracking of the analog signal is used to achieve true

zero speed operation. Advanced calibration algorithms are

used to adjust the device gain and offset at power-up, resulting

in air gap independent switchpoints, which greatly improves

output accuracy. In addition, advanced algorithms mitigate the

effect of system anomalies such as target vibration and sudden

changes in air gap.

The regulated current output is configured for two-wire

operation. This sensor IC is ideal for obtaining edge and duty

cycle information in gear-tooth–based applications such as

transmission speed.

The ATS685 is provided in a 4-pin SIP package that is lead

(Pb) free, with 100% matte tin leadframe plating.

ATS685LSH-DS

Two-Wire, Zero Speed

Differential Gear Tooth Sensor IC

Package: 4-pin SIP (suffix SH)

Functional Block Diagram

Not to scale

ATS685LSH

GND

VCC

TEST

Multiplexor

Voltage

Regulator

Hall

Amp

Offset

Adjust

Reference

Generator

and

Lockout

PDAC

AGC

Synchronous Digital Controller

NDAC