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TPS40170 in Webench

Jamaal_Charles
Genius 3245 points
Other Parts Discussed in Thread: TPS40170, LM5119, LM25119

Hello,

I'm trying to design a circuit with the TPS40170.  I used Webench with my requirements, 22-36Vin, 13Vout.  Most of the time it will only draw 2A, but it will have occasional pulses at 13A for 50ms.  If I put the load at 13A for worst case, the TPS40170 doesn't show up as an option.  I thought the TPS40170 is capable of 20A, is that correct?  If so, why would it not show up in Webench as an option?  If I lower the load to 10A, it does show up.  Is this the right device for my requirements, or should I use something else.  The reason I wanted to use the TPS40170 is that it seems to be a good device for the rest of my loads. 

Thanks,

J

  • 0
    TI__Genius 14317 points

    Hi JC,

    I ran Webench for 35 V in, 13 Vout @ 13 A and did indeed see that the TPS40170 is listed as unacceptable for this design. I checked exception list and filtered for TPS40170 and the reason listed is that an exceptable FET could not be found in the Webench Data Base. Try running Webench and let it pick suitable devices and see what you come up with or if you want to use the TPS40170, you can use 10 A for the design and make sure that the FET chosen can handle the 13 A peak currents (short duration).

  • 0 in reply to Jeffery Pfarr
    Prodigy 5 points

    We do have a reference design close to the specs mentioned.

    http://www.ti.com/tool/pmp6680
    48Vin, 12Vout at 20Amps

    It uses parallel fets for both top and bottom in the synchronous buck.

    At this power level, 13V 13A 169W, it may be better to use an interleaved approach.
    Since the PMP6680 points to parallel fets, it would be advantageous to do a 2 phase interleaved, 180degree out of phase.
    This would provide some ripple current cancellation on the input and output.

    When you put in the parameters for 35Vin (33-38) and 13Vout @ 13A, Webench provides 2 interleaved solutions, LM5119 and LM25119.
    The LM25119 looks like a good solution.

  • 0 in reply to Ed Walker
    Prodigy 230 points

    What about using two TPS40170 for two phase operation? Using sync pin to synchronize. I'm not sure about how the two would interact.

    My requirement is 30-45Vin to 24Vout, 5A average with occasional 40A peak.
    BTW, what's the maximum gate drive current?