AS5045 Datasheet, PDF (18/34 Pages) ams AG – 12 BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER

AS5045
Data Sheet
9.1 Changing the PWM Frequency
The PWM frequency of the AS5045 can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see
chapter 11). With PWMhalfEN = 0 the PWM timing is as shown in Table 6:
Table 6. PWM Signal Parameters (default mode)
Parameter
Symbol
Typ
Unit
Note
PWM frequency
lid ^{MIN pulse width}
MAX pulse width
f_PWM
PW_MIN
PW_MAX
244
1
4096
Hz
Signal period: 4097µs
µs
- Position 0d
- Angle 0 deg
µs
- Position 4095d
- Angle 359.91 deg
va ^{When PWMhalfEN = 1, the PWM timing is as shown in Table 7:}
Table 7. PWM Signal Parameters with Half Frequency (OTP option)
ill ^Parameter
PWM frequency
Symbol
f_PWM
Typ
122
Unit
Hz
G ^{t MIN pulse width}
PW_MIN
2
µs
A ^{t s MAX pulse width}
PW_MAX
8192
µs
Note
Signal period: 8194µs
- Position 0d
- Angle 0 deg
- Position 4095d
- Angle 359.91 deg
s _{en 10 Analog Output}
m ^t An analog output can be generated by averaging the PWM signal, using an external active or passive low pass filter.
a ^{n 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.
o _{Figure 9. Simple 2nd Order Passive RC Low Pass Filter}
echnical ^c _{Figure 9 shows an example of a simple passive low pass filter to generate the analog output.}
T^{R1, R2 ≥ 4k7 C1, C2 ≥ 1µF / 6V}
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.
www.austriamicrosystems.com
Revision 1.7
17 – 33