Three-Wire True Zero-Speed Differential Peak-Detecting

Sensor IC with Continuous Calibration

ATS468

11

Allegro MicroSystems, LLC

115 Northeast Cutoff

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

1.508.853.5000; www.allegromicro.com

Device Electrical

Internal Differential

1

2

3

4

5

Figure 7: Operation of Running Mode Gain Adjust

• Position1. The device is initially powered-on. Self-calibration occurs.

• Position 3. The calibration period completes on the third rising output edge, and the device enters running mode.

• Position 4. True target rotation occurs and the correct magnetic signal is generated for the installation air gap. The established signal gain

is too large for the target rotational magnetic signal at the given air gap.

• Position 5. Running mode calibration corrects the signal gain to an optimal level for the installation air gap.

signal “seen” during the calibration period is not representative of

the amplitude of the magnetic signal for the installed device air

gap (see figure 7). Note that in this mode, the gain can be reduced

but not increased, so this algorithm applies only to instances in

which the magnetic signal amplitude during running is higher

than that during calibration.

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