as5045 austriamicrosystems, as5045 Datasheet - Page 7

• Manufacturer Part Number: as5045
• Description: 12-bit Programmable Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5045 12-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER
5
The AS5045 provides a pulse width modulated output
(PWM), whose duty cycle is proportional to the measured
angle:
The PWM frequency is internally trimmed to an accuracy
of ±5% (±10% over full temperature range). This
tolerance can be cancelled by measuring the complete
duty cycle as shown above.
Angle
0 deg
(Pos 0)
359.91 deg
(Pos 4095)
5.1
The PWM frequency of the AS5045 can be divided by two
by setting a bit (PWMhalfEN) in the OTP register (see
chapter 7). With PWMhalfEN = 0 the PWM timing is as
shown in Table 6:
Revision 1.2, 03-Oct-06
Position
Parameter
MAX pulse
frequency
MIN pulse
PWM
Pulse Width Modulation (PWM)
Output
width
width
Table 6: PWM signal parameters (default mode)
Changing the PWM Frequency
=
t
(
t
on
on
1µs
PW
Symbol
⋅
Figure 7: PWM output signal
+
PW
4097
PW
f
PWM
t
MIN
off
MAX
MIN
)
−
1
4096
Typ
244
1
1/f
PWM
PW
Unit
Hz
µs
µs
MAX
Signal period:
4097µs
- Position 0d
- Angle 0 deg
- Position 4095d
- Angle 359,91 deg
4096µs
4097µs
Note
www.austriamicrosystems.com
When PWMhalfEN = 1, the PWM timing is as shown in
Table 7:
6
An analog output can 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 AS5045 can be used as direct
replacement of potentiometers.
Pin12
PWM
Figure 8 shows an example of a simple passive lowpass
filter to generate the analog output.
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.
Table 7: PWM signal parameters with half frequency (OTP option)
Pin7
VSS
Parameter
MAX pulse
MIN pulse
frequency
PWM
width
width
Analog Output
Figure 8: Simple 2
R1
Symbol
PW
PW
f
PWM
C1
C1,C2 ≥ 1µF / 6V
MAX
MIN
n d
order passive RC lowpass filter
8192
R2
Typ
122
2
C2
Unit
Hz
µs
µs
analog out
VDD
- Position 4095d
- Angle 359,91 deg
Signal period:
4097µs
- Position 0d
- Angle 0 deg
0V
0°
Page 7 of 23
Note
360°