2000 Sep 05

4

Philips Semiconductors

Product specification

Integrated rotational speed sensor

KMI16/1

FUNCTIONAL DESCRIPTION

The KMI16/1 sensor is sensitive to the motion of ferrous

gear wheels or reference marks. The functional principle is

shown in Fig.3. Due to the effect of flux bending, the

different directions of magnetic field lines in the

magnetoresistive sensor element will cause an electrical

signal. Because of the chosen sensor orientation and the

direction of ferrite magnetization, the KMI16/1 is sensitive

to movement in the ‘y’ direction in front of the sensor only

(see Fig.2).

The magnetoresistive sensor element signal is amplified,

temperature compensated and passed to a Schmitt trigger

in the conditioning integrated circuit (see Fig.4). The digital

output signal level is independent of the sensing distance

within the measuring range (see Fig.10). A (3-wire) output

current enables safe transfer of the sensor signal to the

detecting circuit (see Fig.5). The integrated circuit housing

is separated from the sensor element housing to optimize

the sensor behaviour at high temperatures.

handbook, halfpage

y

z

xx

IC

sensor

magnet with

direction of

magnetization

MBK767

Fig.2 Component detail of the KMI16/1.

handbook, full pagewidth

gear wheel

magnet

magnetic

field lines

(a)

(b)

(c)

direction

of

motion

(d)

MRA957

sensor

y

z

Fig.3 Functional principle.