as5040 austriamicrosystems, as5040 Datasheet - Page 13

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

AS5040 10-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER
8
An analog output may be generated by averaging the
PWM signal, using an external active or passive lowpass
filter. The analog output voltage is proportional to the
angle: 0°= 0V; 360° = VDD5V.
Using this method, the AS5040 can be used as direct
replacement of potentiometers.
Revision 1.8
Pin12
PWM
Parameter
MAX pulse
Pin7
VSS
frequency
MIN pulse
PWM
width
width
Analog Output
U
V
W
CW Direction
Figure 11: Simple passive 2
Position:
Angle:
Commutation - Mode 3.0
Table 5: PWM signal parameters
R1
Symbol
PW
PW
f
PWM
MAX
MIN
0.0
0
C1
0.9756 kHz Signal period: 1025µs
1024
Typ
1
R2
Figure 12: U, V and V-signals for BLDC motor commutation (Div1=0, Div0=0)
n d
C2
Unit
order lowpass filter
µs
µs
60.12
171
Width: 512 Steps
- Position 0d
- Angle 0 deg
- Position 1023d
- Angle 359,65 deg
analog out
VDD
0V
0°
Note
119.88
341
(One-pole-pair)
360°
www.austriamicrosystems.com
180.0
512
Mode 3.2 (3.3) is used for motors with two pole pairs
requiring a higher pulse count to ensure a proper current
commutation. In this case the pulse width is 256 positions,
equal to 90 degrees.
The precise physical angle at which the U, V and W signals
change state (“Angle” in Figure 12 and Figure 13) is
calculated by multiplying each transition position by the
angular value of 1 count:
Angle [deg] = Position x (360 degree / 1024)
R1,R2 ≥ 4k7
R1 should be ≥4k7 to avoid loading of the PWM output.
Larger values of Rx and Cx will provide better filtering
and less ripple, but will also slow down the response
time.
9
Brushless DC motors require angular information for
stator commutation. The AS5040 provides U-V-W
commutation signals for one and two pole pair motors. In
addition to the three-phase output signals, the step (LSB)
output
measurement. Two resolutions (9 or 10 bit) can be
selected by programming Div0 according to Table 6.
Mode 3.0 (3.1) is used for brush-less DC motors with
one-pole pair rotors. The three phases (U, V, W) are 120
degrees apart, each phase is 180 degrees on and 180
degrees off.
Brushless DC Motor Commutation
Mode
at
240.12
683
pin
Width: 512 Steps
12
C1,C2 ≥ 1µF / 6V
allows
299.88
853
high
accuracy
360.0
0
Page 13 of 27
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