AS5046 AB austriamicrosystems, AS5046 AB Datasheet - Page 3

• Manufacturer Part Number: AS5046 AB
• Description: BOARD ADAPTER AS5046
• Manufacturer: austriamicrosystems

Specifications of AS5046 AB

• Sensor Type: Magnetic, Rotary Position
• Sensing Range: 360°
• Interface: Serial
• Voltage - Supply: 9V
• Embedded: No
• Utilized Ic / Part: AS5046
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption
• Sensitivity: -

AS5046 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-linearity 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 Figure 4).
Revision 1.0
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
3.9 mm
Circle of Hall elements
on chip: 2.2mm diameter
Defined
center
3.9 mm
www.austriamicrosystems.com
The AS5046 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 (10bit) at
a sampling rate of 96µs (10kHz; Default) or 384µs
(2.6kHz).
The digital angle information is available in several
formats: as serial 10-bit data stream, as pulse-width
modulated (PWM) signal or as quadrature incremental
signal.
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