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TPS54A20: Efficiency including VG

gomi.ryota
Prodigy 140 points
Part Number: TPS54A20

Hi TI Experts, 

I have 3 questions about the Efficiency around the VG pin of the TPS54A20.

1. It says that applying 5V to the VG+ pin turns off the internal LDO, which improves efficiency, but what is the loss of this LDO?

2. If a DCDC that steps down 12V to 5V is applied to VG+, does that mean that the difference in efficiency between the internal LDO and the prepared DCDC will improve efficiency?

3. It seems that the lower the supply voltage to VG+, the lower the loss. What is the minimum rating for VG+?　(Is it possible to calculate the value of the current flowing through the VG pin when the voltage is changed?)

Thank you for your confirmation.

  • +1
    TI__Mastermind 18370 points

    Hi Gomi,

    1) The loss is about (Vin - 4.8)*0.06, for example for Vin=12V, the loss is about 0.43 Watts!

    2) Yes, that is indeed the case.

    3) You have to supply about 5V to the VG+, it has to be more than 4.8V, and better not be much higher. So 5V is the optimal voltage.

    Hope this helps,

    Regards,

    Yitzhak Bolurian