Let's say i have a clock signal which i control its frequency making it going from 10Hz to 1000Hz. And i want to convert this to PWM signal, so that 10Hz gives 0% duty cycle and 1000Hz gives 100% duty cycle.
How can i make such conversion?

Note: What i'm trying to do in reality is control a DC motor with a Stepper motor driver, The stepper motor driver output Dir and Pulsation signals, and i want to take the pulsation signal (that varies in frequency according to speed) and use it to control the DC motor.

  • \$\begingroup\$ Have you taken a look in 555 timer circuit that generates pwm signal . Also you may need a closed loop controller and dc motor with encoder to replace the stepper motor functionalty exactly. \$\endgroup\$
    – ElectronS
    Commented Jan 26, 2016 at 9:56
  • \$\begingroup\$ Is this linear with frequency or logarithmic with frequency? At the midpoint frequency (say 100 Hz) are you wanting your 100 Hz input clock to be exactly a 100 Hz 50% duty output clock i.e. no change or are you wanting your input frequency only to set the duty cycle of some arbitrary frequency that is not connected? Is your input duty cycle 50% or might this vary? \$\endgroup\$
    – Andy aka
    Commented Jan 26, 2016 at 10:00
  • \$\begingroup\$ @ElectronS I know that 555 timer can output a PWM signal, but i need a way to convert the clock signal i have to maybe some voltage level and then feed it to the timer. \$\endgroup\$
    – Apastrix
    Commented Jan 26, 2016 at 12:45
  • \$\begingroup\$ @Andyaka No it's not logarithmic, i want it to be proportional, so varying frequencies will produce varying duty cycles. \$\endgroup\$
    – Apastrix
    Commented Jan 26, 2016 at 12:47
  • \$\begingroup\$ At what target PWM frequency (the same as the input frequency or fixed at some other value)? \$\endgroup\$
    – Andy aka
    Commented Jan 26, 2016 at 13:51

1 Answer 1


You can convert your clock signal to dc voltage using frequency-to-voltage convert circuit/ic, and then you can convert dc voltage to PWM signal using pwm signal generator circuit/IC.

  • \$\begingroup\$ I thought about this, but i don't have experience with FVC, any tutorial would be helpful. \$\endgroup\$
    – Apastrix
    Commented Jan 26, 2016 at 13:57
  • \$\begingroup\$ If you think about any ways to solve your own problem, it is better if you mention in your question. It shows your effort, and also leads to precise answers by others sometimes. And sorry, i don't know specific tutorial, may be you can use Google. \$\endgroup\$ Commented Jan 26, 2016 at 16:48
  • \$\begingroup\$ You can use the clock to trigger a one-shot. The high time duration of the one shot could be 1ms. The duty cycle will be 1% at 10 Hz, and 100% at 1kHz, and in between in between. But the frequency will be the same as the input frequency. If you don't want the frequency to be the same as input, you can use an RC filter to convert the output of the one shot to a DC voltage. That will be your FVC. \$\endgroup\$
    – user57037
    Commented Jan 27, 2016 at 2:30

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