ATS692LSH datasheet(9/12 Pages) ALLEGRO

9 / 12 page

Two-Wire, Differential, Vibration Resistant

Sensor IC with Speed and Direction Output

ATS692LSH(RSNPH)

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 ATS692, 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

VPROC 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.

Output pulses of tw(ND) are supplied during calibration. Figure 6

shows where the first output edges may occur for various starting

target phases.

Vibration Detection

Algorithms embedded in the IC digital controller detect the

presence of target vibration through analysis of the two magnetic

input channels.

In the presence of vibration, output pulses of tw(ND) may occur or

no pulses may occur, depending on the amplitude and phase of

the vibration (figure 7). Output pulses have a width of tw(ND) until

direction information is validated on constant target rotation.

ICC

Target

Differential

Magnetic

Profile

Target Rotation

Opposite

valley

Opposite

rising edge

Opposite

tooth

Opposite

falling edge

Device Location at Power-On

tW(FWD) or

tW(REV)

tW(ND)

tW(FWD) or

tW(REV)

tW(FWD) or

tW(REV)

tW(ND)

tW(FWD) or

tW(REV)

tW(FWD) or

tW(REV)

tW(ND)

tW(FWD) or

tW(REV)

tW(FWD) or

tW(REV)

Tooth

Valley

Figure 6. Start-up position effect on first device output switching

Figure 7. Output functionality in the presence of Running mode target vibration

Target

Differential

Magnetic

Profile

Normal Target Rotation

Vibration

Normal Target Rotation

tW(ND)

tW(FWD)

[ or tW(REV) ]

tW(FWD)

[ or tW(REV) ]

tW(FWD)

[ or tW(REV) ]

tW(FWD)

[ or tW(REV) ]

Tooth

Valley

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