HALL-EFFECT,

DIRECTION-DETECTION

SENSORS

115 Northeast Cutoff, Box 15036

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

APPLICATIONS INFORMATION

Operation with Fine-Pitch Ring Magnets. For

targets with a circular pitch of less than 4 mm, a perfor-

mance improvement can be observed by rotating the front

face of the sensor subassembly (see below). This sensor

rotation decreases the effective sensor-to-sensor spacing,

provided that the Hall elements are not rotated beyond the

width of the target.

Applications. It is strongly recommended that an

external 0.01

µF bypass capacitor be connected (in close

proximity to the Hall sensor) between the supply and

ground of the device to reduce both external noise and

noise generated by the internal logic.

The simplest form of magnet that will operate these

devices is a ring magnet. Other methods of operation,

such as linear magnets, are possible. Extensive applica-

tions information on magnets and Hall-effect sensors is

also available in the “Hsall-Effect IC Applications Guide”

which can be found in the latest issue of the Allegro

MicroSystems Electronic Data Book, AMS-702 or Appli-

cation Note 27701, or at

www.allegromicro.com

Dwg. MH-024

α

TARGET FACE WIDTH, F

>1.50 SIN

>0.059 SIN

A

0.059"

1.50 mm

12

4

5

3

Rotated sensor for

fine-pitch ring

magnets