AS5045

Data Sheet

www.austriamicrosystems.com

Revision 1.7

25 – 33

15 Simulation Modeling

Figure 20. Arrangement of Hall Sensor Array on Chip (principle)

With reference to Figure 20, a diametrically magnetized permanent magnet is placed above or below the surface of

the AS5045. The chip uses an array of Hall sensors to sample the vertical vector of a magnetic field distributed

across the device package surface. The area of magnetic sensitivity is a circular locus of 1.1mm radius with respect

to the center of the die. The Hall sensors in the area of magnetic sensitivity are grouped and configured such that

orthogonally related components of the magnetic fields are sampled differentially.

The differential signal Y1-Y2 will give a sine vector of the magnetic field. The differential signal X1-X2 will give an

orthogonally related cosine vector of the magnetic field.

The angular displacement (

Θ) of the magnetic source with reference to the Hall sensor array may then be modelled

by:

()

()

°

±

−

−

=

Θ

5

.

0

2

1

2

1

arctan

X

X

Y

Y

The

±0.5° angular error assumes a magnet optimally aligned over the center of the die and is a result of gain

mismatch errors of the AS5045. Placement tolerances of the die within the package are

±0.235mm in X and Y

direction, using a reference point of the edge of pin #1 (see Figure 20).

In order to neglect the influence of external disturbing magnetic fields, a robust differential sampling and ratiometric

calculation algorithm has been implemented. The differential sampling of the sine and cosine vectors removes any

common mode error due to DC components introduced by the magnetic source itself or external disturbing magnetic

fields. A ratiometric division of the sine and cosine vectors removes the need for an accurate absolute magnitude of

the magnetic field and thus accurate Z-axis alignment of the magnetic source.

the die. In addition to this range, an additional offset of

±5mT, caused by unwanted external stray fields is allowed.