True Zero-Speed Low-Jitter High Accuracy

Gear Tooth Sensor

ATS625LSG

15

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Sensor and Target Evaluation

-400

-350

-300

-250

-200

-150

-100

-50

0

50

100

150

200

250

300

0

30

60

90

120

150

180

Target Rotation (°)

0.75

1.00

1.50

2.00

2.50

3.00

AG

(mm)

Magnetic Map, Reference Target 60+2 with ATS625

0

100

200

300

400

500

600

700

800

0.5

1.0

1.5

2.0

2.5

3.0

3.5

AG (mm)

Air Gap Versus Magnetic Field, Reference Target 60+2 with ATS625

Magnetic Profile

In order to establish the proper operating specification for a

particular sensor and target system, a systematic evaluation of

the magnetic circuit should be performed. The first step is the

generation of a magnetic map of the target. By using a calibrated

device, a magnetic profile of the system is made. Figure 10 is a

magnetic map of the 60+2 reference target.

A single curve can be derived from this map data, and be used to

describe the peak-to-peak magnetic field strength versus the size

of the air gap, AG. This allows determination of the minimum

amount of magnetic flux density that guarantees operation of the

allowable AG for the sensor and target system. Referring to fig-

mately 2.5 mm.

Figure 10. Magnetic Data for the Reference Target 60+2 with ATS625. In the top panel, the Signature Region appears in the center of the plot.