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  1. #21
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    Re: Buck converter vs buck-boost converter

    He's probably referring to the 4-switch circuit (like the LT8705) with 2 fets replaced by diodes (which I've also referenced a couple times). That essentially is a cascaded buck with a boost but with only one inductor between them.

    https://www.eenewspower.com/content/...est-efficiency


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  2. #22
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    Re: Buck converter vs buck-boost converter

    Hi,

    No single topology is generally more efficient than the others. Your selection should be based on your particular application. Switch utilization is what is used to determine which topology is best suitable for your application.
    -------------
    --Akanimo.


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  3. #23
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    Re: Buck converter vs buck-boost converter

    based on my understanding, treez answer is makes the most sense.

    question: buck-boost regulator or buck regulator? which one is more efficient

    Treez's answer: we need to see the regulator scheamtic. usually regulator will have FET as switches at the output. if the regulator have one FET at the output, it's the best because switching loss will be less as compared to two separate switches.

    sorry Treez, i cannot like your answer because i liked answers before you 1st. i will click like on your answer tomorrow.



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  4. #24
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    Re: Buck converter vs buck-boost converter

    Comparison of buck versus buck-boost. Identical component values.
    DCM operation. Duty cycles adjusted to obtain similar output voltages.

    Click image for larger version. 

Name:	buck conv waveforms compare to buck-boost ident inV out V.png 
Views:	6 
Size:	52.1 KB 
ID:	156219


    Buck type needs longer duty cycle.

    Buck-boost waveforms are more extreme amplitude.



  5. #25
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    Re: Buck converter vs buck-boost converter

    Referring to the original question, I think it's not obvious that the OP refers to inverting buck-boost as introduced in post #13. It's not clear if the inverting topology is appropriate.

    The initial post asks for efficiency. I conclude that synchronous topology (transistor switch instead of diode) should be preferred. Also routing the total transferred power through a storage inductor as in inverted buck-boost or flyback should be avoided because it involves additional losses (higher copper and core losses, increased switching losses due to higher peak current and switch voltage).

    Respectively, if you need buck-boost operation, a four switch converter is the most efficient solution.


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  6. #26
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    Re: Buck converter vs buck-boost converter

    I would say a well designed, loosely coupled, sepic converter is a contender for the high efficiency stakes - having designed quite a few up to 400kHz for "buck & boost" operation



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