ATS665LSG

TRUE ZERO-SPEED GEAR TOOTH SENSOR

Start-up Detection:

Since the sensor powers up in the OFF state (logic high output), the first edge seen by the sensor can be missed if the

switching induced by that edge reinforces the OFF state. Therefore, the first edge that can be guaranteed to induce an

output transition is the second detected edge. This device has accurate first electrical falling edge detection. The tables

below show various start-up schemes.

MECHANICAL

TARGET PROFILE

SENSOR OUTPUT

(Start-up over Valley)

MAGNETIC PROFILE

(High over Tooth)

SENSOR OUTPUT

(Start-up over Tooth)

SENSOR OUTPUT

(Start-up over Rising Edge)

SENSOR OUTPUT

(Start-up over Falling Edge)

Sensor start-up location

High over Tooth

Final Version, Rev 2.0; MN; 19Dec05

Page 6

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

Copyright © 1993, 1995, 2005 Allegro MicroSystems, Inc.

MECHANICAL

TARGET PROFILE

SENSOR OUTPUT

(Start-up over Valley)

MAGNETIC PROFILE

(Low over Tooth)

SENSOR OUTPUT

(Start-up over Tooth)

SENSOR OUTPUT

(Start-up over Rising Edge)

SENSOR OUTPUT

(Start-up over Falling Edge)

Sensor start-up location

Low over Tooth