ATS665LSG

TRUE ZERO-SPEED GEAR TOOTH SENSOR

SENSOR OPERATION: SWITCHPOINTS

Switchpoints in the ATS665 are established dynamically as a percentage of the amplitude of the normalized magnetic

signal. Two DACs track the peaks of the normalized magnetic signal (see the section on Update); the switching thresholds

are established at 30% and 70% of the two DAC’s values. The proximity of the thresholds near 50% ensures the most

accurate and consistent switching where the signal is steepest and least affected by air gap variation.

The hysteresis of 40% provides high air gap performance and immunity to false switching on noise, vibration, backlash and

other transient events. Since the hysteresis value is independent of air gap, it provides protection against false switching in

the presence of overshoot that can be induced on the edges of large teeth.

The figure below graphically demonstrates the establishment of the switching threshold levels.

Switching Threshold Levels

0 %

100 %

70 %

30 %

Bop

Brp

Because the threshold are established dynamically as a percentage of the peak-peak signal, the effect of a baseline shift is

minimized. As a result, the effects of offsets induced by tilted or off-center installation are minimized.

Final Version, Rev 1.0; DSD; 01Aug03

Page 9

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