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TPS54341: TPS54302/TPS54308 maximum duty cycle

Polly Chung1
Intellectual 2110 points
Part Number: TPS54341
Other Parts Discussed in Thread: TPS54302, TPS54308, , TPS54240, TPS54260

Dear team,

May I know what is TPS54341/ TPS54302/ TPS54308 of maximum duty? I saw datasheet said that they can operate around 100% duty cycle, but there is no details explanation. So could you please let me know if these three device is suitable for the following requirements? If yes, what spec could we refer to? Why? Thank you.

Vin: 12.3V-17V

Vout: 12V

Iout: 3A

Regards,

Polly Chung

  • 0
    TI__Prodigy 480 points
    The datasheet mentions that these devices can only operate at 100% duty cycle if the BOOT to SW pin is greater than 2.1V. There is a more in-depth explanation in the application note, Methods to Improve Low Dropout Operation With the TPS54240 and TPS54260 (www.ti.com/.../technicaldocuments).

    However, given the small size of the device and your parameters, the temperature of your device will be very high. The LM25805 might be a better alternative because the FET is external rather than internal.
  • 0 in reply to Eric Sato31
    Prodigy 250 points

    HI,Eric : 

    Since the power source of this Power stage application comes from the battery, the battery operating voltage is 16.8-12.3V.
    Requires an Aux power = 3A@12V stable output power,
    According to the above recommendation Device, it seems that Duty = 100% condition must be achieved through external control, which will make the control circuit more complicated.
    Or can TI's have other Boost-buck Device solutions to recommend ? (Internal High&low-Side MOSFET)
    (Space issue, using internal High&low-Side MOSFET is necessary)

    Waiting for a better solution for TI Team.

    Janson chen

  • 0 in reply to JANSON CHEN
    TI__Prodigy 480 points

    Hi Janson,

    For a buck-boost solution, you can refer to the following TI design:

    http://www.ti.com/lit/ug/tidub49/tidub49.pdf

    I realize that your device has an output of 36W rather than the 10-15W specified in the document. However, hopefully, this can lead you in the right direction.