PWM Circuit

Discussion in 'The Projects Forum' started by alectravelyan, Apr 26, 2009.

  1. alectravelyan

    Thread Starter New Member

    Apr 26, 2009

    I'm constructing a Buck Converter and have decided to use the SG3525 chip for the control of the MOSFET switch. I am having a few issues getting info on how to set up the SG3525 for PWM.

    The control interface will work by measuring the voltage and current at the output of the converter, sending this to the microcontroller, then the MC sending a voltage reference to the PWM circuitry to adjust the duty cycle.

    Any help would be hugely appreciated.
  2. bertus


    Apr 5, 2008
  3. Tahmid

    Active Member

    Jul 2, 2008
    Hi alectravelyan,
    When using SG3525, you do not need to use microcontroller as SG3525 has its internal comparators for adjusting duty cycle with suitable feedback.
    I will try to help you, but put forward your requirements.
  4. alectravelyan

    Thread Starter New Member

    Apr 26, 2009
    Thanks for the info.

    I wish to use the sg3525 for the generation of the pwm signal, but I want to use an analogue output on a microcontroller to vary the duty cycle of the PWM. The reason for this is that I wish to obtain a specific V.I charactersitic at the output of the converter.

    So depending on the output current of the converter the MC will have a lookup table to determine the value of voltage that must be at the output. This voltage is determined by the duty cycle of the PWM signal.

    I know it is possible to do all of this in a MC, however my coding skills are fairly poor so Im tryin to avoid as much coding as possible.

    Cheers mates.
  5. alaajh

    New Member

    Aug 2, 2008
    thank you very m