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Question about TPS54427.

watanabe
Expert 1740 points
Other Parts Discussed in Thread: TPS54227, TPS54627, TPS54427

Hi,

My customer has questions.

Q1.

Datasheet P15 of TPS 54427,
From the Power Supply Recommendations section,
Vout ÷ 0.65 or more is required.

further,
The voltage drop due to Rds is added to Vout ÷ 0.65,
I think VIN is necessary.
VIN> Vout / 0.65 + Rds * Iout

When VIN is less than Vo / 0.65 + Rds * Iout,
What kind of problems do you encounter?

Q2.

I checked the data sheet of TPS54627, TPS54227 which seems to be a different output voltage product.

In TPS54227,
There is a section on Power Supply Recommendations.
There is no description of Vo / 0.65.

In TPS54627,
There is not even a section of Power Supply Recommendations.

TPS54427 only Please tell us why Vo / 0.65 is recommended and required.

Best regards,

-Watanabe

  • 0
    TI__Guru**** 191445 points
    The Vin > Vout / 0.65 suggestion comes from the minimum off time limitation. You can actually operate at lower Vin (higher duty cycle) but the voltage regulation degrades slightly as duty cycle increases to the maximum. Also the transient response becomes worse as there is no available duty cycle headroom. Maximum duty cycle varies slightly from device to device within that family and also is dependent on operating condition. You will have to check it based on the operating frequency and output voltage and current.

    The Power Supply Recommendations section is new. It will only show up in datasheets that have been updated to the latest standards. It may take a few years for all to be updated as there are many thousands of datasheets already published.
  • 0 in reply to JohnTucker
    Expert 1740 points
    Hi Tucker-san,

    I appriciate for your support.

    Thank you for your Easy to understand explanation.

    Best Regards.

    -Watanabe