Siemens HKZ121 Datasheet
HKZ 121
Hall-Effect Vane Switch
Features
● Contactless switch with open collector
output (40 mA)
● Static switching
● High switching frequency
● Hermetically sealed with plastic
● Unaffected by dirt, light, vibration
● Large temperature and voltage range
● Integrated overvoltage protection
● High interference immunity
● Integrated capacitors for EMI protection
PackageType Ordering Code
HKZ 121 Q67000-A9097-A401 P-HKZ-3-1
HKZ 121
Bipolar IC
P-HKZ-3-1
The Hall-effect vane switch HKZ 121 is a contactless switch consisting of a monolithic
integrated Hall-effect circuit and a special magnetic circuit hermetically sealed in a plastic
package. The switch is actuated by a soft-iron vane which is passed through the air gap
between magnet and Hall sensor.
The main application field is in cars, i.e. as a breakerless trigger in electronic ignition systems.
Numerous industrial applications can be found in control engineering, especially in those areas
where switches must operate maintenance-free under harsh environmental conditions (e.g.
rpm sensor, limit switch, position sensor, speed measurement, shaft encoder, scanning of
coding disks, etc.).
HKZ 121
Function
The Hall-effect switch is actuated by a soft-iron vane that passes through the air gap between
magnet and Hall-effect sensor. The vane short-circuits the magnetic flux before the hall-effect
sensor, as shown below. The open collector output is conductive (low) when the vane is
outside the air gap, and blocks (high) when the vane is introduced into the air gap. The output
remains high as long as the vane remains in the air gap. This static function does not require
a minimum operating frequency. The output signal shape is independent of the operating
frequency.
The circuit features integrated overvoltage protection against most of the voltage peaks occurring in automotive and industrial applications. The output stage has a Schmitt trigger characteristic. Most electronic circuits can be driven directly due to the open collector output current
of max. 40 mA.
a) Magnetic flux through the
Hall-effect switch
with no vane
in the gap
b) Magnetic flux
short-circuited by
the soft-iron
vane
Principle of Operation
Mechanical Characteristics
The Hall-effect vane switch is hermetically sealed in a special plastic package, so that it can
also be used under harsh environmental conditions. The package is waterproof, vibrationresistant and resistant to gasoline, oil and salt. Two tubular rivets are incorporated in the
package to mount the sensor on its carrier plate. The circuit has three flexible leads for power
supply, output and ground.
HKZ 121
Application Notes
The output current of the "open collector" must be limited to the maximum permissible value
by a load resistor adapted to the application.
For optimum efficiency of the integrated overvoltage protection, it is suggested that a resistor
of approx. 100 Ω be provided in the component's power supply to limit the current.
Absolute Maximum Ratings
Parameter Symbol
Unit Test ConditionLimit Values
min. max.
Supply voltage
Output voltage in OFF-state
Inverse supply current
VS
VQ
–I
– 1.2
– 0.8
S
–
24
30
30
200
V
V
V
mA
(limited externally)
Output current
Inverse output current
Ambient temperature
Storage temperature
IQ
–IQ
TA
Tstg
–
–
– 40
– 40
40
30
135
150
mA
mA
˚C
˚C
Thermal resistance
system - air R
th SA – 170 K/W –
Operating Range
Supply voltage VS 4.5 24 V –
Ambient temperature TA – 40 130 ˚C –
Vane
1)
: thickness
width
gap length
immersion depth
gap height
a
b
c
h
d
0.5
8
8
4.6
7.3 – h
mm
mm
mm
9
mm
mm
–
A = 25 ˚C
T
–
TA ≤ 80 ˚C
≤ 1 h
t
without vane
–
–
–
–
–
–
–
1)
see Figure Mechanical Measurement Conditions
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