Magnetic Field Sensors
Angle Sensor KMT 31
Function principle
Magnetoresistive materials can change their resistivity in an external magnetic field. The
variation of the resistivity is determined by the rotation of magnetisation with respect to the
direction of the current flow. Permalloy (Ni Fe ) is commercially used as
81 19
magnetoresistive material. The relative change of resistivity is 2-3 % for this material. The
high sensitive and small size sensor consists of a silicon chip coated with thin film
permalloy stripes. These stripes form a Wheatstone bridge whose output voltage depends
on the magnetic field.
Characteristic
Magnetic fields vertical to the chip surface have no influence on the output voltage. A
strong magnetic field H ? 50 kA/m parallel to the chip surface causes a sinusoidal output
rot
signal which is determined by the angle between field direction and orientation of the
permalloy stripes of the Wheatstone bridge. The field H is created by a permanent
rot
magnet which rotates over the sensor. The sensor output gives information about the
direction of the magnet. The output characteristic of an additional galvanic seperated
Wheatstone bridge is 45° phase shifted compared with the other bridge.
Vmax1
Bridge 1
Bridge 2
0,8
0,6
0,4
0,2
Output voltage of both
0 0 Wheatstone bridges versus
angle aaaa of the magnetic field
-0,2
direction
-0,4
-0,6
-0,8
Vmin-1
0° 45° 90° 135° 180° 225° 270° 315°
360°[(cid:1)]
Application
The KMT 31 allows the contactless counting of the revolutions of a rotating magnet which
is mounted on the axis of a wheel. Zero output voltages of the Wheatstone bridges are
used as trigger signals. The sense of rotation of the wheel is taken into account by
comparing the signal outputs of both Wheatstone bridges which are proportional to
sin2(a) or sin2(a + 45°). The angle can be determined by evaluating these signals.
Alternatively it is possible to use the voltage signals of four half bridges which are trimmed
on V /2.
b
Sensors in thin film technology
HL-Planartechnik GmbH
Hauert 13, D - 44 227 Dortmund, Tel.: +49 (0) 231/97400, Fax.: +49 (0) 231/974020
Internet: http://www.hlplanar.com E-Mail: service@hlplanar.deMagnetic Field Sensors
Angle Sensor KMT 31
Technical data
Absolute maximum ratings
Parameter Symbol Unit Value
Supply voltage VB V 5
Total power dissipation Pto mW 120
Operating temperature range Tamb °C -40 ... + 125
Storage temperature range Tstg °C -65 ... +125
Sensor chip alignment error ae ° ￡ 2
Electrical characteristics (T = 25°C, H ???? 25 kA/m)
amb rot
Condition
Parameter Symbol Unit Value bridge 2 bridge 1
Bridge resistance RB kOhm 3 – 1.0
Offset voltage VOFF /VB mV/V ￡ – 2.0 a=0° a=45°
Half bridge symmetry (Vs/2 - Vo)/VB mV/V ￡ – 2.0 a=0° a=45°
Sensitivity S
a
(mV/V)/° > 0.418 a=0° a=45°
Output voltage range (|Vmax|+ |Vmin|) /VB mV/V ? 24
Zero offset angle hysteresis Da ° ￡ 1
Temperature coefficients ( - 25 °C < T < 125 °C)
amb
of bridge 1 and 2
Parameter Symbol Unit Value
Bridge resistance TCBR %/K 0.30 – 0.05
Open circuit sensitivity
(VB = const) TCSV %/K -0.30 – 0.05
(IB = const) TCSI %/K 0.00 – 0.05
Offset voltage TCOFF (μV/V)/K ￡ – 3
Housing of KMT31: SM-8
bridge 1:
pin 4: + V (GND)
B
pin 8: GND (+V )
B
pin 1: - V (+ V )
0 0
pin 5: + V (- V )
0 0
bridge 2:
pin 3: + V (GND)
B
pin 7: GND (+ V )
B
pin 2: - V (+ V )
0 0
pin 6: + V (- V )

KMT31磁阻傳感器是一種高精度的磁性傳感元件，屬于磁敏電阻（Magnetoresistive Sensor）的一種類型。它主要利用了磁阻效應原理，即在某些材料（如GMR或TMR——巨磁阻效應或隧道磁阻效應材料）中，當磁場作用時，其電阻值會隨磁場強度的變化而變化。KMT31具體可能指的是某一款具有特定技術參數(shù)和性能指標的產(chǎn)品，例如線圈結構、工作頻率、靈敏度、分辨率、測量范圍等。 這種類型的傳感器常用于各種應用領域，比如汽車電子、工業(yè)自動化、航空航天、消費電子設備等，以實現(xiàn)對磁場強度、位置、速度或者方向的精確檢測。例如，在汽車的ABS（防抱死制動系統(tǒng)）、EPS（電動助力轉向系統(tǒng)）以及電機控制等方面有著廣泛應用。在使用過程中，用戶需要根據(jù)具體應用場景選擇合適的安裝方式、供電電壓、信號處理電路等相關配套設備，以確保其準確性和穩(wěn)定性。