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    Bulk capacitor series with 1 ohm resistor

    Hi

    I found attached schematics image which has red cycle that has bulk capacitor series with 1 ohm resistor . Can I know the reason series resistor hare as well as the capacitor does not mention the polarities

    Click image for larger version. 

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    Please advice
    Thanks in advanced

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    Re: Bulk capacitor series with 1 ohm resistor

    We are using capacitor with series resistors in some cases to increase the ESR intentionally, e.g. with a ceramic capacitor as bypass capacitor for voltage regulators that require the ESR for stability. Also to reduce the Q of LC low pass filters. In this place, the series resistor doesn't seem to make sense.



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    Re: Bulk capacitor series with 1 ohm resistor

    Maybe to reduce the current surge when something is connected to the right connector (which has the "VMM" net).


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    Re: Bulk capacitor series with 1 ohm resistor

    This capacitor+resistor in parallel with another capacitor configuration is used to dampen inductive resonance in power supplies due to the interaction of parasitic inductances with bypass capacitors.

    If you want to read more about it, Google the title of this article: “Bypass or decouple your way to power supply noise reduction”. EDN and EEtimes both have the same article I’m referring to.


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    Re: Bulk capacitor series with 1 ohm resistor

    Quote Originally Posted by std_match View Post
    Maybe to reduce the current surge when something is connected to the right connector (which has the "VMM" net).
    I also believe that this may be used protect from surge current because at the beginning of the capacitor consume high current and result is low voltage at the output, then regulator try to increase output violate by reference with feedback



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