• Resolved

UC1825: Regarding usage of UC1825 for 1MHZ switching frequency CCM Flyback converter

Part Number: UC1825

Is it possible to use UC1825 in 5V, 5A output (CCM) flyback converter operating at switching frequency of 1MHz?

  • Hi Kamlesh,

    As highlighted in the datasheet oscillator can operate up to 1Mhz. As the two output pulses Out A and Out B will be offset as in Push-pull configuration.  How are you planning to drive the flyback Mosfet? 

    Can you sketch a schematic as to what you have in mind.

    If you use one of the output i.e. Out A  to drive the flyback Mosfet  then flyback will be operating at half the oscillator frequency. 

  • In reply to Ramesh Khanna:

    Out A is used to directly drive MOSFET. Flyback converter is operating in CCM with an output power of 50W.

  • In reply to kamlesh sawant1:

    Hi Kamlesh,

    For any single ended application , oscillator frequency is equal to output frequency. As flyback will be a single ended application thus its switching frequency will oscillator frequency that can go up to 1Mhz as highlighted in the datasheet.
    Note for push-pull converter applications output frequency will be one-half the oscillator frequency.

    If it addressed your question, please verify the post.
  • In reply to Ramesh Khanna:

    Sir,

    Could you please explain configuration of UC1825 for single ended application? Does it require shorting of OUTA and OUTB pins?