Description

The ATS617 gear-tooth sensor IC is a peak-detecting device

that uses automatic gain control and an integrated capacitor

to provide extremely accurate gear edge detection down to

low operating speeds. Each device consists of a high-tem-

perature plastic shell that holds together a samarium-cobalt

pellet, a pole piece, and a differential open-collector Hall 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 technology used for this device is Hall-effect based. The

device incorporates a dual-element Hall IC that switches in

response to differential magnetic signals created by fer-

romagnetic targets. The sophisticated processing circuitry

contains an A-to-D converter that self-calibrates (normal-

izes) the internal gain of the device to minimize the effect of

air gap variations. The patented peak-detecting filter circuit

provides immunity to magnet and system offsets and has the

ability to discriminate relatively fast changes such as those

caused by tilt, gear wobble, and eccentricities. This easy-to-

integrate solution provides first falling edge detection and

stable operation to extremely low rpm. The ATS617 can be

used as a replacement for the ATS616.

The ATS617 is ideal for use in systems that gather speed,

position, and timing information using gear-tooth-based

ATS617LSG-DS, Rev. 1

Features and Benefits

▪ Self-calibrating for tight timing accuracy

▪ First-tooth detection

▪ Immunity to air gap variation and system offsets

▪ Immunity to signature tooth offsets

▪ Integrated capacitor provides analog peak and

valley information

▪ Low timing-accuracy drift with temperature changes

▪ Low radiated emissions

▪ Integrated, series resistor on VCC pin for improved

transient immunity

▪ Large air gap capability

▪ Small, integrated package

▪ Optimized magnetic circuit

▪ Undervoltage lockout (UVLO)

▪ Wide operating voltage range

Dynamic, Self-Calibrating, Peak-Detecting, Differential

Hall Effect Gear Tooth Sensor IC

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Package: 4-pin SIP (suffix SG)

Not to scale

ATS617LSG

GND

VOUT

VC

C

Voltage

Regulator

TEST

Hall

Amp

Reference

Generator

Gain

Current

Limit

(Recommended)

Hall

Amp

Track and

Hold

Track and

Hold

UVLO

Power-On

Logic

Tooth and Valley

Comparator

Functional Block Diagram