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  1. #1
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    LDO & BUck Converter

    Final end node without jumpers.pdfFinal end node without jumpers.pdf

    Hello
    I have a supply voltage of around 4.5V consisting of 3 AA batteries. I need this stepped down to 3.3V. My current requirement is around 150mA. So currently I am considering 2 options:-
    1) Using a LDO IC to obtain 3.3v
    2) Using a buck converter

    I have uploaded my entire schematic above.
    Some of my concerns are that
    1) Will smps(inductor coil) interfere with my zigbee signals .
    2) If i use a LDO will i need a heat sink assuming that my heat dissipated will be around 0.3W.

    Also it would be of great help if someone could recommend some highly efficient ICs for LDO & BuckBoost , considering the fact that there are so many of them available online.

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  2. #2
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    Re: LDO & BUck Converter

    I think 0.3W is not too much, even small packages can dissipate this, or the PCB. The SMPS is bigger issue, I am not sure anyone can guarantee that any converter's radiated or conducted spectra has no harmonic products in the desired band. The battery discharge time maybe is an other concern, then it makes sense to rethink.
    "Try SCE to AUX." /John Aaron/



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  3. #3
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    Re: LDO & BUck Converter

    Consider using 2 of the modern Energizer Advanced Lithium type. The AA size puts out 1.8 volt new (regardless of being labelled 1.5V). The instructions warn against re-charging.

    If your battery pack is 4.5V, then 2 diodes drop 1.2V. They'd get warm but heat sink isn't necessary .

    Or are they rechargeable type? Then expected voltage is in a range that just 1 diode could bring it down to 3.3V.



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  4. #4
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    Re: LDO & BUck Converter

    here is a SMPS power module that can do the job for you....

    https://recom-power.com/pdf/Eval-Boa...-1.0-EVM-1.pdf

    buck is maybe no good as the battery will drop to 3.3v maybe and then you cant make 3.3 vout from 3.3 vin

    Traco also make power modules.

    - - - Updated - - -

    here also is one
    http://www.farnell.com/datasheets/27...SAAEgIZSfD_BwE

    - - - Updated - - -

    In fact , type in "power supplies" in farnell search tab, and you will see many...i would pick for you but my internet is horribly slow.



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