Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

PWM help for Tl494

  1. Mar 6, 2009 #1

    I am trying to build an inverter and i am using Tl494 for my PWM, i am getting the right frequency but am not getting the 50% duty cycle. Can anyone suggest me any ideas on how to adjust the duty cycle for Tl494

  2. jcsd
  3. Mar 7, 2009 #2
  4. Mar 7, 2009 #3


    User Avatar

    Staff: Mentor

    Why are you looking for 50% duty cycle? The max in the datasheet is 45%, and the duty cycle would be dependent on .... Quiz Question -- dependent on what?
  5. Mar 8, 2009 #4
    I will use MOSFETs and i will use PWM to turn on or off. I need the 50% duty cycle to turn the mosfets on and off for same period.
    I am trying to make an inverter for 50 Hz. The example given in the data sheet gives the duty cycle of 45% but has max frequency. I want the PWM osc. frequency to be 50 Hz. And I AM NOT SURE IF PWM OSC. FREQ WILL BE MY MOSFETs OUTPOT FREQUENCY OR NOT?
    Moreover, i was able to get the PWM to 50 Hz but my duty cycle was 10% and i tried increasing the reference voltage but still didn't help.

  6. Mar 9, 2009 #5
    The duty cycle can be adjusted by adjusting the voltage on the feedback pin(3). This is normally used for voltage regulation in a power supply.
  7. Mar 9, 2009 #6
    Thanks again, I had tried that before but I had ref v to be 5v. I think it was a problem since my comparator triang wave had pk-pk of 2.6v I was able to vary now with ref v from 0-.7v. Thanks again for the information
    Now I have to drive MOSTETs with this pwm signal. Can I get heads up on how to make MOSFETs switching to get AC out?

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook