Large Air Gap, GMR Transmission

Speed Sensor IC for Gear Tooth Sensing

ATS19480

9

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

FUNCTIONAL DESCRIPTION

Sensing Technology

The sensor IC contains on-chip GMR elements that are used to

detect magnetic signals created by an adjacent target. These trans-

ducers provide electrical signals containing information regarding

edge position of target rotation. The ATS19480 is intended for

use with ferromagnetic targets.

After proper power is applied to the sensor IC, it is capable of

providing digital information that is representative of the fea-

tures of a rotating target. The waveform diagrams in Figure 3

present the automatic translation of the target profiles, through

their induced magnetic profiles, to the digital output signal of the

sensor IC.

Data Protocol Description

When a target passes in front of the device (opposite the branded

face of the package case), the ATS19480 generates an output

pulse for each mechanical edge of the target.

Target Design

The ATS19480 is designed to work with a variety of target

shapes and sizes in addition to the Reference Target 60-0 in this

datasheet. It is recommended that to determine the operating air

gap range for each target, the magnetic profile of each should be

analyzed.

BRP

BOP

Device Orientation to Target

(Pin 1

Side)

(Pin 3

Side)

IC

Package Case

Branded Face

(Top View of

Package Case)

Back-Biasing

Rare-Earth Pellet

Channel

IC

IC Internal Differential Analog Signals

Device Output Signal

Mechanical Position (Target moves past device pin 1 to pin 3)

This tooth

sensed earlier

This tooth

sensed later

+B

Target

Target Magnetic Profile

Channel

Element Pitch

Figure 3: Magnetic Profile