• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 600 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

LM25037 - RAMP DOES NOT START

LM25037: Trouble Getting This Guy Switching

Tim Simpson
Prodigy 90 points
Part Number: LM25037

Above is a picture of my circuit.

I am trying to use this IC as a half bridge driver for a high voltage transformer at 21kHz, and output filtering is not an option with the space constraints I have. This is making it very difficult for me to follow the datasheets instructions for R and C sizing, as they all depend on output filters...Is my only option voltage mode control if this is my case?

I am having a lot of trouble under any load getting this guy to switch for me, any help would be appreciated!

(Note: The drains are connected to either end the center-tapped transformer primary with the Vin appearing on the center wind, just as the data sheet shows)

  • 0
    TI__Genius 13660 points
    Hi Tim, I will get back to you shortly. Thanks.
  • 0 in reply to Teng Feng
    TI__Genius 13660 points
    Hi Tim,

    In your attached picture, there is no output R and C filter. It will be better if you could provide the complete schematic.
    May I understand that your question is that R and C sizing of output filter in your design is too large? And I have not found instructions for R and C sizing in datasheet that you mentioned.
    I think that large R and C size is because of low operating frequency 21Khz in your design, could you consider to improve the operating frequency?
    Conventionally, current mode control is used for push-pull and full-bridge typologies while voltage mode control is required for the half-bridge topology.

    Regards，
    Teng
  • 0 in reply to Teng Feng
    TI__Genius 13660 points
    Hi Tim,I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out) – thanks,——Teng