as5043 austriamicrosystems, as5043 Datasheet - Page 15

• Manufacturer Part Number: as5043
• Description: 10-bit Programmable 360? Magnetic Angle Encoder With Absolute Digital And Analog Outputs
• Manufacturer: austriamicrosystems

AS5043 Programmable 360° Magnetic Angle Encoder
14 Alignment Mode
The alignment mode simplifies centering the magnet over
the chip to gain maximum accuracy and XY-alignment
tolerance.
This electrical centering method allows a wider XY-
alignment tolerance (0.485mm radius) than mechanical
centering (0.25mm radius) as it eliminates the placement
tolerance of the die within the IC package (+/- 0.235mm).
Alignment mode can be enabled with the falling edge of
CSn while PROG = logic high (Figure 16). The Data bits
D9-D0 of the SSI change to a 10-bit displacement
amplitude output. A high value indicates large X or Y
displacement, but also higher absolute magnetic field
strength. The magnet is properly aligned, when the
difference between highest and lowest value over one full
turn is at a minimum.
Under normal conditions, a properly aligned magnet will
result in a reading of less than 32 over a full turn.
Stronger magnets or short gaps between magnet and IC
may show values larger than 32. These magnets are still
properly aligned as long as the difference between
highest and lowest value over one full turn is at a
minimum.
The MagInc and MagDec indicators will be = 1 when the
alignment mode reading is < 32. At the same time,
hardware pin MagRngn (#1) will be pulled to VSS.
The Alignment mode can be reset to normal operation
mode by a power-on-reset (cycle power supply) or by a
falling edge of CSn with PROG=low (see Figure 17).
PROG
PROG
Revision 1.6, 3-Oct-06
CSn
CSn
Figure 16: Enabling the alignment mode
2µs
min.
Figure 17:Exiting alignment mode
2µs
min.
AlignMode enable
exit AlignMode
Read-out
www.austriamicrosystems.com
Read-out
via SSI
via SSI
15 Choosing the proper Magnet
Typically the magnet should be 6mm in diameter and ≥2.5mm in
height. Magnetic materials such as rare earth AlNiCo, SmCo5 or
NdFeB are recommended.
The magnet’s field strength perpendicular to the die
surface should be verified using a gauss-meter. The
magnetic field B
circle with a radius of 1.1mm (R1), should be in the range
of ±45mT…±75mT. (see Figure 18).
Figure 18: Typical magnet and magnetic field distribution
Vertical field
component
Vertical field
component
Bv
v
at a given distance, along a concentric
0
360
N
(45…75mT)
R1
typ. 6mm diameter
R1 concentric circle;
radius 1.1mm
S
Magnet axis
Magnet axis
360
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