AMR3003 datasheet(3/8 Pages) MULTIDIMENSION

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1. Operating principle

The AMR3003 angle sensors use dual Wheatstone

bridges comprised of eight high sensitivity AMR

sensing elements to increase the sensor’s output

signal amplitude with enhanced temperature

characteristics and anti-interference performance as

shown in Figure 1. The X axis outputs are defined as

Vx+ and Vx-. The X axis output voltage is found by

Vx = (Vx+) - (Vx-). The Y axis outputs are defined as

Vy+ and Vy-. The Y axis output voltage is found by

Vy = (Vy+) - (Vy-). Vx = Asin(2θ) and Vy = Bcos(2θ)

when the magnetic field is at angle θ, where A and B

are constants. The angle θ can thus be determined

through arctangent function.

Vy+

Vy-

VCC

GND

Figure 1. AMR3003 block diagram

By rotating a small magnet placed on top of

AMR3003, a rotating magnetic field parallel to the

surface of the magnetic is generated and is at the

same angle as the magnet. Figure 2 shows the

typical output signals of the AMR3003 in response

to a rotating field. In Figure 2, the rotating magnetic

field is generated by a Helmholtz coil and the supply

voltage is 1V.

As seen in Figure 2, the period of the AMR3003

is 180° and Vx and Vy have a phase shift of 45°.

Figure 2 also illustrates the definition of peak voltage

VPEAK. The output voltage may not be zero at 0°

due the process tolerance, and this VOFFSET can be

calculated by equations 1 and 2. Figure 3 illustrates

the definition of the magnetic field angle.

VPEAK

AMR3003

Magnetic field Angle (°)

-20

-15

-10

-5

90 135 180 225 270 315 360

VCC = 1V

Figure 2. Typical AMR3003 output curve

Figure 3. Definition of measured magnetic field angle

(top view)

VMAX - VMIN

VPEAK =

Equation (1)

VMAX + VMIN

VOFFSET =

Equation (2)

MultiDimension Technology Co., Ltd.

http://www.dowaytech.com/en/

AMR3003

Dual Axis AMR Magnetic Angle Sensor

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