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LM3513 10A Power Supply with High Capacitance Load

David Schanin
Intellectual 270 points
Other Parts Discussed in Thread: LM3153

I have used the Webench to design a simple 12V -> 3.3V 10A converter built around the LM3513.  My concern is that this design has 32 DSPs which require large amounts of local bulk storage capacitance, possibly totaling up to 30K uF.  Obviously this poses real startup issue in terms of peak current and stability.  Can you provide any guidance as to how to structure the power supply so it will start reliably and regulate properly?  Thanks.

  • 0
    TI__Genius 16025 points

    Hi David,

    Can you confirm that the part you are using is an LM3153? If it is here are my suggestions:

    a) Think about having a longer start up by employing the programmable soft start feature on your IC.

    b) ESR will play a major role (have you taken a look at simulations to see how it will affect your startup and stability?)

    c) Maybe split the power design into quad DSP pairs (4DSPs per LM3513), this might result in lower capacitance and better efficiency and operation.

    d) Ensure sufficient trace widths and optimum board layout keeping thermal and electrical paths in mind.

    If you have any further questions, feel free to trouble us!

    Thanks,

    Anston