Three-Wire, Differential, Vibration Resistant

Sensor IC with Speed and Direction Output

ATS693LSG

11

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Start-Up Detection / Calibration

When power is applied to the ATS693, the sensor IC inter-

nally detects the profile of the target. The gain and offset of

the detected signals are adjusted during the calibration period,

normalizing the internal signal amplitude for the air gap range of

the device.

The Automatic Gain Control (AGC) feature ensures that opera-

tional characteristics are isolated from the effects of installation

air gap variation.

Automatic Offset Adjustment (AOA) is circuitry that compen-

sates for the effects of chip, magnet, and installation offsets.

This circuitry works with the AGC during calibration to adjust

signal peaks. AOA and AGC function separately on the two

differential signal channels.

Direction information is available after calibration is complete.

Figure 7 shows where the first output edges may occur for vari-

ous starting target phases.

t

t

Target

Differential

Magnetic

Profile

Target Rotation

Opposite

valley

Opposite

rising edge

Opposite

tooth

Opposite

falling edge

Device Location at Power-On

Target

Differential

Magnetic

Profile

Target Rotation

Opposite

valley

Opposite

rising edge

Opposite

tooth

Opposite

falling edge

Device Location at Power-On

Tooth

Valley

Tooth

Valley

Figure 7: Start-up Position Effect on First Device Output Switching