10

30Dec03, Rev. 1.42

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

115 Northeast Cutoff, Box 15036

www.allegromicro.com

Allegro MicroSystems, Inc.

Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture

ATS672LSB

SENSOR EVALUATION: ACCURACY

The self-calibration algorithm allows the sensor to adapt to

system changes such as air gap increase. However, major

changes in air gap can adversely affect switching performance.

When characterizing sensor performance over a significant air

gap range, be sure to power-off and then power-on the device at

each air gap. This ensures that self-calibration occurs for each

installation condition. See the Operating Charactersitics table for

information on timing accuracy performance.

Edge Position vs. Air Gap

Electrical Rising Edge (Mechanical Falling Edge)

103

103.2

103.4

103.6

103.8

104

104.2

104.4

104.6

104.8

105

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

Air Gap (mm)

ROOM

150ºC

-40ºC

Edge Position vs. Air Gap

Electrical Falling Edge (Rising Mechanical Edge)

ATS672LSB; 8X Reference Target

125

125.2

125.4

125.6

125.8

126

126.2

126.4

126.6

126.8

127

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

Air Gap (mm))

ROOM

150ºC

-40ºC

ATS672LSB; 8X Reference Target

Target

Relative Timing Accuracy

Device Output

T

T

Tooth

Operational Air Gap

Valley

Air Gap