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SN6505D-Q1: About SN6505D-Q1design

Alan Liu15
Intellectual 270 points
Part Number: SN6505D-Q1
Other Parts Discussed in Thread: TL431

Hi Experts, 

I saw this part used in TIDM817 app note. 

For my design, my requirement is 15V/0.1A and -10V/0.1A

Could I modify the R9 and R11 to meet the negative Vout that I need ?

  • 0
    TI__Genius 17610 points

    Hello,

    Thank you for your question. Please allow us one day to review this specific app note and reference design details.

    Regards,
    Darrah

  • +1
    TI__Guru 52890 points

    Hi Alan,

    Thanks for your patience.
    The transformer listed in the design you are referring to has a turns-ratio of 1:3.9 which generates 19V output from 5V input. The Zener like device (mostly TL431) is simply creating an intermediate point from which the positive voltage reads 15V and the negative reads -4V with the total still being 19V.

    If you modify the R9 and R11 resisotrs to get -10V, then the positive voltage will end-up being 9V as the total has to be 19V. For your requirement of +15V and -10V, you would need a transformer that can generate 25V output and a TL431 can be used to create an intermediate point such that the 25V splits into +15V and -10V.

    To conclude, you would need a transformer with higher turns ratio to get 25V output and then can use TL431 to split it into +15V and -10V. Let me know if you have any questions, thanks.


    Regards,
    Koteshwar Rao