7805 works fine, LM2940CT5 not!

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  1. - 29th August 2007, 22:33 #3
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    Bruce
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    Most +5V non LDO regulators require at least 7.5VDC minimum input to maintain a regulated +5V output.
    I couldn't find a datasheet for the LM2940CT5, but, some LDO types require specific capacitor values on
    the output or they will oscillate, and that causes major problems.

    Edit: I found a data sheet on the LM2940, and it looks like you need at least 22uF on the output, and
    drop-out will be around 0.5V, so you don't have much overhead.
    Last edited by Bruce; - 29th August 2007 at 22:49.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com
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