Two-Wire, Differential, Vibration-Resistant Sensor

with Speed and Direction Output

ATS699LSN

11

Allegro MicroSystems, LLC

955 Perimeter Road

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

www.allegromicro.com

Start-Up Detection/Calibration

When power is applied to the ATS699, 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

in the internal A-to-D range to allow for acquisition of signal

peaks. AOA and AGC function separately on the two differential

signal channels.

Direction information is available after calibration is complete.

For the –xxxBx variant, the output becomes active at the end of

calibration. Figure 10 shows where the first output edges may

occur for various starting target phases.

ing calibration.

Figure 11 shows where the first output edges may occur for vari-

ous starting target phases.

Figure 10: Start-Up Position Effect on First Device Output Switching (-xxxBx Variant)

Figure 11: Start-Up Position Effect on First Device Output Switching (-xxxPx Variant)

t

Target

Differential

Magnetic

Profile

Target Rotation

Opposite

Valley

Opposite

Rising Edge

Opposite

Tooth

Opposite

Falling Edge

Device Location at Power-On

Tooth

Valley

t

Target

Differential

Magnetic

Profile

Target Rotation

Opposite

Valley

Opposite

Rising Edge

Opposite

Tooth

Opposite

Falling Edge

Device Location at Power-On

Tooth

Valley