as5040 austriamicrosystems, as5040 Datasheet - Page 19

• Manufacturer Part Number: as5040
• Description: 10-bit Programmable Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5040 10-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER
A buffer capacitor of 100nF is recommended in both
cases close to pin VDD5V. Note that pin VDD3V3 must
always be buffered by a capacitor. It must not be left
floating, as this may cause an instable internal 3.3V
supply voltage which may lead to larger than normal jitter
of the measured angle..
Revision 1.8
4.5 - 5.5V
3.0 - 3.6V
5V Operation
3.3V Operation
100n
VDD5V
VDD5V
Figure 19: Connections for 5V / 3.3V supply voltages
VSS
VSS
LDO
LDO
VDD3V3
VDD3V3
2.2...10µF
Internal
VDD
Internal
VDD
N
T
E
R
F
A
C
E
N
T
E
R
F
A
C
E
I
I
DO
PWM_LSB
CLK
CSn
A_LSB_U
B_Dir_V
Index_W
Prog
DO
PWM_LSB
CLK
CSn
A_LSB_U
B_Dir_V
Index_W
Prog
100n
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13 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 20).
Figure 20: 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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