Philips KMI15-4 Datasheet

DISCRETE SEMICONDUCTORS

DATA SH EET

KMI15/4

Rotational speed sensor

Preliminary specification
File under Discrete Semiconductors, SC17

1996 Dec 05

Philips Semiconductors Preliminary specification

Rotational speed sensor KMI15/4

FEATURES

• Digital current output signal

• Zero speed capability

• Wide air gap

• Wide temperature range

• Vibration insensitive

• EMC resistant.

DESCRIPTION

The KMI15/4 sensor detects rotational speed of ferrous
gear wheels and reference marks

(1)

.
The sensor consists of a magnetoresistive sensor
element, a signal conditioning integrated circuit in bipolar
technology and a ferrite magnet. The frequency of the
digital current output signal is proportional to the rotational
speed of a gear wheel.

CAUTION

Do not press two or more products together against their
magnetic forces.

PINNING

PIN DESCRIPTION

1V

CC

2V−

handbook, halfpage

12

MBH782

(1) The sensor contains a customized integrated circuit. Usage in

hydraulic brake systems and in systems with active brake
control is forbidden.

Fig.1 Simplified outline; (SOT453C).

QUICK REFERENCE DATA

SYMBOL PARAMETER MIN. TYP. MAX. UNIT

V

CC

T

amb

I

CC (low)

I

CC (high)

f

t

DC supply voltage − 12 − V
ambient operating temperature −40 − +85 °C
current output signal low − 7 − mA
current output signal high − 14 − mA
operating tooth frequency 0 − 25000 Hz

d sensing distance 0 to 2.0 0 to 2.3 − mm

1996 Dec 05 2

Philips Semiconductors Preliminary specification

Rotational speed sensor KMI15/4

LIMITING VALUES

In accordance with Absolute Maximum Rating System (IEC 134).

SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT

V

CC

T

stg

T

amb

T

sld

Note

1. With R

(see Fig.7).

CHARACTERISTICS

T

amb

gear wheel: module 2 mm; material 1.0715; unless otherwise specified.

DC supply voltage T

= −40 to +85 °C; RL=115Ω− 16 V

amb

storage temperature −40 +150 °C
operating ambient temperature −40 +85 °C
soldering temperature t ≤ 10 s − 260 °C
output short-circuit duration to GND continuous; note 1

= 115 Ω the device is continuously protected against wrong polarity of DC supply voltage (VCC) to GND

L

=25°C; VCC= 12 V; d = 1.5 mm; ft= 2 kHz; test circuit: see Fig.7; RL=115Ω; sensor positioning: see Fig.15;

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

I

CC (low)

I

CC (high)

t

r

current output signal low see Figs 6 and 8 5.6 7.0 8.4 mA
current output signal high see Figs 6 and 8 11.2 14.0 16.8 mA
output signal rise time CL= 100 pF; see Fig.9;

− 0.5 −µs

10 to 90% value

t

f

output signal fall time CL= 100 pF; see Fig.9;

− 0.7 −µs

10 to 90% value

t

d

switching delay time between stimulation pulse (generated by

− 1 −µs

a coil) and output signal

f

t

operating tooth frequency for both rotation directions 0 − 25000 Hz
d sensing distance see Fig.15 and note 1 0 to 2.0 0 to 2.3 − mm
δ duty cycle see Fig.6 20 50 80 %

Note

1. High rotational speeds of wheels reduce the sensing distance due to eddy current effects (see Fig.17).

1996 Dec 05 3

Philips Semiconductors Preliminary specification

Rotational speed sensor KMI15/4

FUNCTIONAL DESCRIPTION

The KMI15/4 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 KMI15/4 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 (Figs 4 and 5).
The digital output signal level (see Fig.6) is at a fixed level
independent of the sensing distance. A (2-wire) output
current ensables safe sensor signal transport to the
detecting circuit (see Fig.7). The integrated circuit housing
is separated from the sensor element housing to optimize
the sensor behaviour at high temperatures.

handbook, halfpage

y

xx

magnet with
direction of
magnetization

sensor

IC

z

The strength of the magnetic field caused by the
Ferroxdure 100 magnet in the different sensor directions,
measured at the centre of the magnetoresistive bridge, is
typically: H

= 7 kA/m (auxiliary field) and Hz= 17 kA/m

x

(perpendicular to the sensor surface). Hy is zero due to the
trimming process.

handbook, full pagewidth

gear wheel

magnetic

z

sensor

magnet

y

(a) (b) (c)

field lines

MBH779

Fig.2 Component detail of the KMI15/4.

direction

of

motion

(d)

MRA957

Fig.3 Functional principle.

1996 Dec 05 4

Philips Semiconductors Preliminary specification

Rotational speed sensor KMI15/4

handbook, full pagewidth

VOLTAGE CONTROL

AMPLIFIERSENSOR

Fig.4 Block diagram.

SCHMITT
TRIGGER

CONSTANT

CURRENT

SOURCE

SWITCHABLE

CURRENT

SOURCE

V

MRA958

CC

V

handbook, full pagewidth

sensor

EMC

FILTER

pre-
amplifier

switchable

current source

Schmitt-
trigger

Fig.5 Simplified circuit diagram.

1996 Dec 05 5

power supply

constant
current source

V

ref

GAP

MRA959

V

CC

V