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TPS54620 pin to pin replacement for lower output current

Eric Hooker1
Prodigy 170 points
Other Parts Discussed in Thread: TPS54620, TPS54320

Hello,

Is there a pin for pin replacement for TPS54620 that would provide better efficiency at lower output currents (0.5 Amps).  Vin = 12V, Vout = 3.3V

Thanks,

Eric

  • 0
    TI__Guru**** 191445 points

    TPS54320 is the pin compatible lower current version.   TPS54620 will get better efficiency as it has lower on resistance FETs.  We do offer some parts with eco-mode for netter light load efficiency in the same input voltage range, but they are not pin compatible with TPS54620.

  • 0 in reply to JohnTucker
    Prodigy 170 points

    John,

    Thanks for your reply.  When I compare the efficiency curves on page 1 for both data sheets, the 3 Amp part (TPS54320) has better efficiency than the 6A part (TPS54620) for my application (Vin=12v, Vout=3.3V, load current=0.5A).   

    The curves indicate 94% efficiency for the 3 A part and 88% efficiency for the 6 A part. Or am I misreading the curves?

    Thanks,

    Eric 

  • 0 in reply to Eric Hooker1
    TI__Guru**** 191445 points

    I'm not sure about the test conditions for those two graphs.  They are definitely different frequency.  While I am sure that it is actual measured data, we will typically pick the best available measurement for the front page as the front page is considered "marketing" information.  I ran a quick comparison in Webench.  For Vin = 12 V, Vout = 3.3 V, Iout = 0.5A, Fsw = 200 kHz, TPS54320 shows 91.79% and TPS54620 shows 94.98%.  Since TPS54620 has lower RDSon for the switching FETs, I would expect it to have better efficiency than TPS54320 under identical circumstances.  You could always get an EVM and test it with your exact components.  In general, Fsw and inductor selection will have the most effect on efficiency.

  • 0 in reply to JohnTucker
    Expert 1445 points

    The TPS54620 efficiency plot test condition was Fsw=480 kHz and the TPS54320 efficiency plot used Fsw=500 kHz so they are very close.  Does TI have additional efficiency plots for these two parts that you could post here?

    I will evaluate both parts but data from TI is good for comparison purposes.

    Thanks,

    Eric