HKZ 121
Hall-Effect Vane Switch
Features
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HKZ 121
Bipolar IC
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
P-HKZ-3-1
Type
HKZ 121
Ordering Code
Package
Q67000-A9097-A401 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 occur-
ring in automotive and industrial applications. The output stage has a Schmitt trigger charac-
teristic. 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, vibration-
resistant 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
Supply voltage
Output voltage in OFF-state
Inverse supply current
(limited externally)
Output current
Inverse output current
Ambient temperature
Storage temperature
Thermal resistance
system - air
Operating Range
Supply voltage
Ambient temperature
Vane
1)
:
thickness
width
gap length
immersion depth
gap height
V
S
T
A
a
b
c
h
d
4.5
– 40
0.5
8
8
4.6
7.3 – h
24
130
V
˚C
mm
mm
mm
mm
mm
–
–
–
–
–
–
–
Symbol
V
S
V
Q
– I
S
I
Q
– I
Q
T
A
T
stg
R
th SA
Limit Values
min.
max.
– 1.2
– 0.8
–
–
–
– 40
– 40
–
24
30
30
200
40
30
135
150
170
Unit
V
V
V
mA
mA
mA
˚C
˚C
K/W
Test Condition
–
T
A
= 25 ˚C
–
T
A
≤
80 ˚C
t
≤
1 h
without vane
–
–
–
9
1)
see Figure Mechanical Measurement Conditions
HKZ 121
Characteristics
V
S
= 5 V to 18 V,
T
A
= – 30 to 130 ˚C
Parameter
Output saturation
voltage
Symbol
V
Q sat
Limit Values
min.
max.
–
–
–
0.4
0.6
10
12
1
42
42
Unit
–
–
V
V
µ
A
Test Condition
without vane
I
Q
= 40 mA
T
A
= – 30 to 110 ˚C
T
A
= 110 to 130 ˚C
with vane
without vane
I
Q
= 40 mA
I
S
= 16 mA
I
S
= 16 mA
Output reverse current
Supply current
Fall time
Overvoltage protection
– Supply voltage
(V
S
)
– Output
(V
Q
)
I
Q R
I
S
t
HL
V
SZ
V
S0
–
–
–
32
32
mA
µ
s
V
V
Switching Point Characteristics
Definitions
In most applications, the switching point is set exactly by mechanical adjustment, thus
compensating all mechanical tolerances in the system including the scatter of the Hall-effect
vane switch. For the function of the device in operation, only the deviations of those
characteristics are important on temperature and operating voltage.
The characteristic values of the switching points are, therefore, not directly referred to the
mechanical dimensions of the vane switch, but to an electrically defined symmetry B
0
according to formula 1):
1)
B
0
= (ON
left
+ OFF
left
+ ON
right
+ OFF
right
): 4
B
0
= A
0
±
0.3 mm
The definition of the operate and release points is shown the following figure.
Operate point
f
ON
is obtained by subtracting the measured ON operate value from the reference
point B
0
:
2)
f
ON
= ON
right
–
B
0
=
B
0
– ON
left
The release point
f
OFF
is calculated from the difference between the appropriate ON and OFF
points:
3)
f
OFF
= ON
right
– OFF
right
= OFF
left
– ON
left
f
ON 0
and
f
OFF 0
are the switching points measured for the individual component under normal
conditions (V
S
= 12 V,
T
A
= 25 ˚C) within the characteristic device deviation.
The deviations of the operate and release points are defined according to 4):
4)
∆
f
ON
=
f
ON
–
f
ON 0
∆
f
OFF
=
f
OFF
–
f
OFF 0
HKZ 121
Switching Point Definitions
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