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Forum Decoupling capacitors behavior on power-off
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Related

Decoupling capacitors behavior on power-off

modelrailwaycat
modelrailwaycat over 9 years ago

Hello,

 

I am designing a home control system which contains a 'net' of multiple PCBs. Each PCB has several decoupling capacitors, namely 1 large 100 uF capacitor near the power supply connector (5V), and several 100nF spread on the board close to the ICs Vcc pins (between 6 and 10 per board). The finished system will include about 60 boards like this, separated several centimeters or even meters one of each other, and all of them powered by the same power supply. So at the end all the capacitors will be paralelled to the power rails.

 

My question is about the behavior of the system when the power will be turned off. At this point, I realize I will have an equivalent +6000 uF capacitor. What should be considered regarding the design of the system or the power supply in order to guarantee a safe operation?

 

Thank you very much in advance!

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  • mcb1
    mcb1 over 9 years ago +1
    What should be considered regarding the design of the system or the power supply This is an excellent example of good engineering. The turn off shouldn't be much of an issue, as each board will draw…
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  • D_Hersey
    D_Hersey over 9 years ago

    Sometimes, especially when on-card linear regulators were common, a 'backwards' diode was placed the I and O terminals to protect it from the bypass caps.

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  • D_Hersey
    D_Hersey over 9 years ago

    Sometimes, especially when on-card linear regulators were common, a 'backwards' diode was placed the I and O terminals to protect it from the bypass caps.

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