Combining PWM and PFM

[tsmitht0229]

I am new to 555 timers and circuit design. I am trying to figure out a way to control the duty cycle and frequency. I need a controllable frequency from 15kHz to 60kHz and to be able to adjust the duty cycle for motor speed control. Is this possible?

 

[Audioguru]

PWM is good for controlling motor speed. But why do you want to change the frequency?

 

[BradtheRad]

The 555 has a 'ctl' pin. By applying a voltage, you change duty cycle. At the same time it changes frequency. If you're lucky the resulting waveform will suit your purpose.



Also check out this collection of 555 circuits.

**broken link removed**

 

[tsmitht0229]

The speed adjust on the motor datasheet says the PWM frequency of 15kHz-60kHz, 2.3-5VDC. So I have made a circuit to adjust duty cycle but I think I still have to adjust frequency. Is the correct?

 

[dick_freebird]

If it's a DC motor then it doesn't care about frequency,
it either will be filtered (LC) or self-filtered (motor L).