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  1. #1
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    PS with LM76003 for variable volatage and variable current design?

    LM76003 is 3.5A Synchronous Step-Down Voltage Converter.
    I want to use it for design power suplly with variable output voltage 1-45 with with current range near 0 to 3,5A.

    My operating conditions:
    Input vopltage 50V.
    Switching frequency 350-500kHz
    Output voltage 1-42V
    Output current tens of mA - 3,5A
    And I have a few questions.,

    1.Choice of output coil and capacitors.
    Output coil.
    Due to the large output current range I oversized it and even at a high switching frequency I consider 47uH 4.5A

    2. Output capacitors.
    I thing SMD ceramic 2x 47uF 100V size 1812 + 8x 10uF 100V size 1210 = 147uF in SMD ceramics, plus any small 100nF/330nF.
    It is recommended to use more capacity in ceramics or add aluminium for example 470uF LXZ ?

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  2. #2
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    Re: PS with LM76003 for variable volatage and variable current design?

    When you draw high power your output capacitors have to carry 1 or 2 Amperes per cycle. That's thousands of times per second. It may be all right to have a gang of several surface mount capacitors as listed in your specs.

    If you attach very large uF, then it may draw large surge current at power-up.



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  3. #3
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    Re: PS with LM76003 for variable volatage and variable current design?

    lots of input capacitance is necessary to make it stable ...



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