High-Performance GMR AK Protocol

Wheel Speed and Direction Sensor IC

A19351

7

Allegro MicroSystems

955 Perimeter Road

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

www.allegromicro.com

FUNCTIONAL DESCRIPTION

The A19351 sensor IC contains a single-chip GMR circuit that uses

spaced elements. These elements are used in differential pairs to

provide electrical signals containing information regarding edge

position and direction of rotation. The A19351 is intended for use

with ring magnet targets as shown in Figure 8. The IC detects the

peaks of the magnetic signals and sets dynamic thresholds based on

these detected signals.

Forward Rotation

For the -F variant, when the target is rotating such that a target

feature passes from pin 1 to pin 2, this is referred to as forward

rotation. For the -R variant, forward direction is indicated for target

rotation from pin 2 to 1.

Reverse Rotation

For the -F variant, when the target is rotating such that a target

feature passes from pin 2 to pin 1, this is referred to as reverse

rotation. For the -R variant, reverse direction is indicated for target

rotation from pin 1 to 2.

Figure 7: Package Orientation

Bx

Bz

By

Pin 1

Figure 8: Target Orientation Relative to Device

Rotation

Pin 1

Figure 9: Basic Operation

ICC(HIGH)

ICC(MID)

ICC(LOW)