www.austriamicrosystems.com/AS5145

Revision 1.10

18 - 36

AS5145

Data Sheet - D e t a i l e d D e s c r i p t i o n

8.2.1 Changing the PWM Frequency

The PWM frequency of the AS5145 can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5145 on

page 19). With PWMhalfEN = 0 the PWM timing is as shown in Table 11:

When PWMhalfEN = 1, the PWM timing is as shown in Table 12:

8.3 Analog Output

An analog output can be generated by averaging the PWM signal, using an external active or passive low pass filter. The analog output voltage

Using this method, the AS5145 can be used as direct replacement of potentiometers.

Figure 12. Figure 11: Simple 2nd Order Passive RC Low Pass Filter

Figure 11 shows an example of a simple passive low pass filter to generate the analog output.

R1,R2

C1,C2

(EQ 2)

R1 should be greater than or equal to 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 11. PWM Signal Parameters (Default mode)

Symbol

Parameter

Typ

Unit

Note

PWM frequency

244

Hz

Signal period: 4097µs

MIN pulse width

1

µs

- Position 0d

- Angle 0 deg

MAX pulse width

4097

µs

- Position 4095d

- Angle 359.91 deg

Table 12. PWM Signal Parameters with Half Frequency (OTP option)

Symbol

Parameter

Typ

Unit

Note

PWM frequency

122

Hz

Signal period: 8194µs

MIN pulse width

2

µs

- Position 0d

- Angle 0 deg

MAX pulse width

8194

µs

- Position 4095d

- Angle 359.91 deg

R1

R2

analog out

Pin12

PWM

Pin7

VSS

C1

C2

VDD

0V

0º

360º