TLE 4921-3U

Data Sheet

9

2000-07-01

Application Configurations

Two possible applications are shown in Figure 7 and 8 (Toothed and Magnet Wheel).

The difference between two-wire and three-wire application is shown in Figure 9.

Gear Tooth Sensing

In the case of ferromagnetic toothed wheel application the IC has to be biased by the

south or north pole of a permanent magnet (e.g. SmCO

the dimensions 8 mm

× 5mm × 3 mm) which should cover both Hall probes.

The maximum air gap depends on

– the magnetic field strength (magnet used; pre-induction) and

– the toothed wheel that is used (dimensions, material, etc.; resulting differential field)

Figure 5

Sensor Spacing

Figure 6

Toothed Wheel Dimensions

a centered distance

of Hall probes

b Hall probes to

IC surface

L IC surface to

tooth wheel

= 2.5 mm

= 0.3 mm

a

b

b

L

a

N

S

AEA01259

d

T

AEA01260

Conversion DIN – ASA

m = 25.4 mm/p

T = 25.4 mm CP

DIN

d

diameter (mm)

z

number of teeth

m

module

T

pitch

ASA

p

diameter pitch

p

=

PD

pitch diameter PD =

CP

circular pitch

CP = 1 inch

× π/p