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PWM help for Tl494

  1. Mar 6, 2009 #1
    Hi,

    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
    Thanks.

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

    berkeman

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    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.

    Thanks
     
  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?

    Thanks
     
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