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TPS65265: Operation at VIN=4.5 and switching frequency

Tom Perman94
Prodigy 90 points
Part Number: TPS65265

Hi,

I am planning to use TPS65265 as a secondary regulator to generate the following rails:

0.85V @ 5A

1.2V @ 2A

1.8V @ 1A

From reading the datasheet it says that V7V is generated as 6.1V typical, using an LDO from PVIN1=12V. Since an LDO is used clearly V7V must be <4.5V when a 4.5V input voltage is used. Therefore I wanted to confirm that operation from this input voltage will be OK?  

In addition it is not explained how the selection of switching frequency should be made. There is a wide range of possible frequencies that could be used. Can a methodology for selection be proposed?

Thanks,

Tom

  • 0
    TI__Mastermind 19080 points

    Hi Tom,

    1. It can work well with 4.5V VIN, although V7V is lower than 6.1V.
    2. The selection of switching frequency is a trade-off between efficiency and solution size. Generally speaking, with higher switching frequency, you can use a smaller inductor, but the efficiency will be lower due to the switching loss. There are other considerations, such as EMI requirements, Ton/Toff limitation...
    Any further question, please let me know. Thanks.

    Regards,
    Sam