ATS612LSB

DYNAMIC, SELF-CALIBRATING, PEAK-DETECTING,

DIFFERENTIAL HALL-EFFECT GEAR-TOOTH SENSOR

13

www.allegromicro.com

Operation with Fine-Pitch gears. For targets with a

circular pitch of less than 4mm, a performance improve-

ment can be observed by rotating the front face of the

sensor. This sensor rotation decreases the effective

sensor-to-sensor spacing and increases the capability of

detecting fine tooth or valley configurations, provided that

the Hall elements are not rotated beyond the width of the

target.

to pin 4), the output of the device will switch from LOW to

HIGH as the leading edge of the target passes the module,

which means that the output will be HIGH when the unit is

facing a tooth.

Dwg. AH-007

1

2

3

4

Dwg. AH-006-1

1

2

3

4

Power Supply Protection. The sensor contains an on-

chip voltage regulator and can operate over a wide supply

voltage range. For devices that need to operate from an

unregulated power supply, transient protection should be

added externally. For applications using a regulated

supply, external EMI/RFI protection is often required.

Insufficient protection can result in unexplained pulses on

the output line, providing inaccurate sensing information to

the user.

The filter capacitor and EMI protection circuitry can

easily be added to a PC board for use with these devices.

Provisions have been made for simple mounting of a

board on the back of the unit.

Dwg. MH-018-1

A

2.235 mm

0.088"

α

TARGET FACE WIDTH, F

>2.235 SIN

>0.088 SIN

Signal Timing Accuracy. The magnetic field profile width

is defined by the sensor element spacing and narrows in

degrees as the target diameter increases. This results in

improved timing accuracy performance for larger gear

diameters (for the same number of gear teeth).

Valley-to-tooth transistions will generally provide better

accuracy than tooth-to-valley transitions for large-tooth or

large-valley configurations. For highest accuracy, targets

greater than 100mm in diameter should be used.

Signal Duty Cycle. For repetitive target structures,

precise duty cycle is maintained over the operating air gap

and temperature range due to an extremely good symme-

try in the magnetic switch points and the internal self

calibration of the device. For irregular tooth geometries,

there will be a small but measureable change in pulse

width versus air gap.

Output Polarity. The output of the device will switch from

HIGH to LOW as the leading edge of the target passes the

module in the direction indicated below (pin 4 to pin 1),

which means that the output will be LOW when the unit is

facing a tooth. If rotation is in the opposite direction (pin 1

APPLICATIONS INFORMATION — Continued