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TPS543B20: Choice between TPS543B20 and TPS53355

diverger
Expert 1275 points
Part Number: TPS543B20
Other Parts Discussed in Thread: TPS53355

I'm choosing a DC-DC converter for a design with Vin = 12V in, Vout =  5V, and Iout = 15A, target for FPGA power rails. The two candidate chips are TPS53355, and TPS543B20.  TPS543B20 use a true fixed frequency control method, so it's transient response may be slow, right? So the datasheet take some words to explain this, such as load step-up/down. So, compared with TPS53355, for same load transient, which one will behave better? And it seems the fixed frequency may be easier for EMI filter.

Any suggestions? Which one should I choose?

Thanks.

  • 0
    TI__Expert 7500 points

    Hi,

    David will feedback to you on Monday US time.

    Thanks,

    Lishuang

  • +1
    TI__Expert 5310 points

    Hello,

    If transient response is the primary performance metric, I would recommend the TPS53355. The TPS533555 uses a DCAP (adaptive on-time) control topology, which is capable of faster transient response when compared to the TPS543B20. However, as you mentioned the TPS543B20 is a true fixed frequency part if that's what your system requires. Ultimately, the speed and peak-to-peak variation of the TPS543B20's transient response will depend on the inductor selection, output capacitance, and RAMP selection.

    I would recommend simulating each part in Webench to get an idea for how well each part addresses the specifications of the system. If you have any additional system requirements, please post in this thread, and I can provide further guidance.

    Regards,

    Alec Biesterfeld