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I'm looking for a buck converter with 100%Duty cycle capabilty - 12V to 36V DC input range - output: 16-18V, 2-3A

Bruno Scherrer
Intellectual 820 points
Other Parts Discussed in Thread: LMR16030, TPS54560

Hi,
I'm looking for a buck converter (ideally with integrated switch) that can support 12V to 36V DC input range for delivering an output voltage around 16 to 18V (output current around 2-3A).
Most of the time this converter will operate at an input voltage lower than output voltage (between 12V and 15V DC), therefore 100% duty capability is an important feature.

Thanks for your help.
Best regards,
 Bruno

  • 0
    TI__Genius 13735 points

    hi, Bruno,

    The buck device can work dropout mode, that is Vout will follow and =Vin. Is this your requirement? then Vin> 18V, Vout =18V, Vin<18V, Vout=Vin.

    Choose a 60V 3A grade buck, like LMR16030 LMR76003 family . 

    Elena 

  • 0 in reply to Elena Gao
    Intellectual 820 points

    Hi Elena,
    Thank you for your reply.
    I took a look at the devices you suggest but none seem to completely meet my expectations.
    The closest appears to be the TPS54560 as it can handle 100% duty at Vin = Vout, but only as long as the BOOT voltage to SW is above 2.1V as mentioned in the chapter "7.3.4 Low Operation drop and startup voltage (BOOT)".
    This means that the chip will switch less, therefore approaoching 100%duty without really reaching it, as mentionned in pargraph "7.1 Overview": "the TPS54560to operate at high duty cycles approaching 100%."

    However, there are devices like the TPS6282x or TPS6209x (with integrated switch) that actually work at 100% duty full-time and it's clearly written in their datasheet.
    Unfortunately, they do not support the required input voltage range.
    I tryied the power management parametric search page but without success...

  • 0 in reply to Bruno Scherrer
    TI__Genius 13735 points

    hi, Bruno,

    TPS54560 may have boot UVLO concern when working Vin close to Vout condition. and the Toffmin will limit the D to ~99%. 

    Elena

  • 0 in reply to Elena Gao
    TI__Genius 13735 points

    Please reopen this thread if you have more question ,otherwise I will close first.

    Elena