High-Accuracy, Pulse-Width or AK Protocol

Hall-Effect Wheel Speed and Direction Sensor IC

A19302

7

Allegro MicroSystems

955 Perimeter Road

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

www.allegromicro.com

Target

S

S

BDIFF

TCYCLE

N

S

N

Target Cycle; the amount of rotation that moves one north and one

south pole across the sensor

TCYCLE =

The differential magnetic flux density sensed by the sensor

BDIFF =

Figure 3: Definition of TCYCLE

Figure 4: Single Period-to-Period Variation

Figure 5: Repeated Period-to-Period Variation

B

n

B

n+m

Applied B

DIFF

T

WINDOW

B

n

B

n+m

Applied B

DIFF

T

WINDOW