ATS610LSC

DYNAMIC, PEAK-DETECTING,

DIFFERENTIAL HALL-EFFECT

GEAR-TOOTH SENSOR

TYPICAL ATS610LSC OPERATING CHARACTERISTICS

(with reference target) — Continued

3.5

2.5

1.5

10

30

50

70

0.5

REFERENCE TARGET SPEED IN RPM

Dwg. GH-011-6

20

40

60

3.0

2.0

1.0

0

-40

°C

+25

°C

+150

°C

4.0

3.5

2.5

1.5

500

1500

2500

3500

0.5

REFERENCE TARGET SPEED IN RPM

Dwg. GH-011-5

1000

2000

3000

3.0

2.0

1.0

0

-40

°C

+25

°C

+150

°C

4.0

The ATS610LSC dynamic, peak-detecting, differential

Hall-effect gear-tooth sensor is a Hall IC plus magnet

subassembly that is fully optimized to provide digital

detection of gear-tooth edges in a small package size.

The sensor is packaged in a miniature plastic housing that

has been optimized for size, ease of assembly, and

manufacturability. High operating temperature materials

are used in all aspects of construction.

The application of this sensor is uncomplicated. After

power is applied to the device, it is capable of quickly

providing digital information that is representative of a

rotating gear or specially designed target. No additional

optimization or processing circuitry is required. This ease

of use should reduce design time and incremental assem-

bly costs for most applications.

Sensing Technology. The gear-tooth sensor subassem-

bly contains a single-chip differential Hall-effect sensor IC,

a samarium-cobalt magnet, and a flat ferrous pole piece.

The Hall IC consists of two Hall elements spaced 2.235

DEVICE DESCRIPTION

mm (0.088") apart, which senses the magnetic gradient

created by the passing of a ferrous object (a gear tooth).

The two Hall voltages are compared and the difference is

then processed to provide a digital output signal.

The processing circuit uses a patented peak-detection

technique to eliminate magnet and system offsets. This

technique allows coupling and filtering of offsets without

the power-up and settling time disadvantages of classical

high-pass filtering schemes. Here, the peak signal of

every tooth and valley is detected and is used to provide

an instant reference for the operate-point and release-

point comparators. In this manner, the thresholds are

adapted and referenced to individual signal peaks and

valleys, thereby providing immunity to zero-line variation

due to installation inaccuracies (tilt, rotation, and

off-center placement), as well as for variations caused by

target and shaft eccentricities. The peak detection

concept also allows extremely low-speed operation when

used with small-value capacitors.