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  1. #1
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    problem with a switcher and LDO. lmr62014 + LT1761

    I have a circuit that require 15Vdc, I used LMR62014 (1.6MHz) initially. The circuit run okay, except the noise a little high.
    so I put a LT1761 after LMR62014. Changed the LMR62014 Vout to 16vdc, and LT1761-byp to 15v.

    I notice the LT1761 Voutput has ripple triangular voltage, several hundred hertz, magnitude about several hundred millivolts.

    I thought it is the LDO issue, changed the bypass cap to tantalum, added 0.5ohm in series with the output, but nothing helped.

    Anyway, I need 15vdc with 10mA of low noise voltage supply, I don't have to use the above switcher, anyone please recommend.

    thank you
    ahgu

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  2. #2
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    Re: problem with a switcher and LDO. lmr62014 + LT1761

    What is your input voltage limited to? Why not use a LM7815. Its voltage regulation is at least better than the several hundred millivolts you said your getting now. Plus you can clean it up a bit after the fact... I guess I'd need a bit more information, such as your input source, output requirements (amps, etc.), and maybe an idea what application this is going to be used for.



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  3. #3
    Full Member level 3
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    Re: problem with a switcher and LDO. lmr62014 + LT1761

    input is 5vdc
    output is 15vdc
    current needed is less than 10mA.



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