AS5045 AB austriamicrosystems, AS5045 AB Datasheet - Page 3

• Manufacturer Part Number: AS5045 AB
• Description: BOARD ADAPTER AS5045
• Manufacturer: austriamicrosystems

Specifications of AS5045 AB

• Sensor Type: Magnetic, Rotary Position
• Sensing Range: 360°
• Interface: Serial
• Voltage - Supply: 9V
• Embedded: No
• Utilized Ic / Part: AS5045
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption
• Sensitivity: -

AS5045 12-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER
Adapter PCB Operation Manual
5 Principle of Operation
5.1
A magnet, having one north / one south pole in the horizontal axis is placed right above the ring of hall elements
(see Figure 2). The magnet does not necessarily need to be circular, it can be rectangular as well, as long as the
north and south pole are arranged horizontally over the center of the hall array ring.
The magnetic field strength along this ring should be in the range of ±45….75 milliTesla (mT).
5.1.1
The size of the magnet should be at least the size of the hall array ring (2.2mm). Smaller magnets are more critical
in terms of misalignment due to the non-linear magnetic field distribution along the circumference of the magnet.
The recommended magnet diameter is 4….6mm
5.1.2
To achieve the required field strength at a reasonable distance (~0.5…5mm), it is recommended to use rare-earth
magnets, such as Samarium-Cobalt (SmCo) or Neodyne-Iron-Boron (NdFeB) magnets.
5.1.3
In theory, the magnet misalignment is not critical for this type of angular measurement. In practice however,
magnets are not perfectly linear. The magnetic field strength does not increase linearly with the radius. As you get
towards the boundary of the magnet, the magnetic field comes to a maximum and then weakens as you move
further away from the center. Therefore, a magnet should be chosen, that is still in the linear range at a <3mm
diameter.
5.1.4
A non-linear magnetic field results in a non-sinusoidal representation of the magnet, which in turn causes non-
linearities in the calculated angle (calculated angle differs from actual angle).
With a perfectly centered magnet, the maximum error is <±0,5 degrees. This error is caused by internal mismatch
and gain errors.
With the recommended 4mm magnet (Bomatec BMN-35H), the maximum error of <±1.4degrees (including
internal errors and temperature related errors) can be achieved while the magnet is off-center by a radius of
<0.25mm (see
Revision A.02, 14-Mar-07
2.433 mm
2.433 mm
Magnet considerations
Magnet size
Magnet distance and material
Magnet misalignment
Non-linearity errors
1
Figure 4: Tolerances of magnet placement
Area of allowed magnet
misalignment: 0.5mm diameter
Figure 4).
3.9 mm
Circle of Hall elements
on chip: 2.2mm diameter
www.austriamicrosystems.com
Defined
center
3.9 mm
The AS5045 chip consists of a ring of hall
elements, placed at the center of the IC at a
circle diameter of 2.2mm (86.6mil).
The hall elements pick up the field of a magnet,
placed atop this hall array circle. This
information is digitized and fed into a digital
signal processor (DSP), which calculates the
angle of the magnet with a resolution of 0.0879
degrees or 4096 positions per revolution (12bit)
at a sampling rate of 96µs (10kHz; Default) or
384µs (2.6kHz).
The digital angle information is available in
several formats: as serial 12-bit data stream, as
pulse-width modulated (PWM) signal or as
quadrature incremental signal
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