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STM32 Input Decoupling Capacitors

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  • STM32 Input Decoupling Capacitors


    In Phil's course video, he picks a 10uF bulk decoupling capacitor and 100nF capacitors for each individual pin. According to the datasheet (see below), it's recommended that a 4.7uF bulk decoupling capacitor is used. I assume it's perfectly fine to use a 10uF capacitor, but I would like to understand why that's the case. What are the ramifications of using a larger valued bulk decoupling capacitor? Is there an upper limit to this value (i.e. can it be too big?) and how would you go about determining that?

    In Phil's video #11 on his YouTube channel, he picks the 4.7uF capacitor instead for this same microcontroller. I'm assuming the main reason behind picking the 10uF capacitor in this specific case, was for the purposes of BOM consolidation.

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    Thanks in advance.
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  • #2
    Too big is determined by the voltage regulator and the wanted bandwidth.
    As for the microcontroller, there is no upper limit.
    There is of course the question of anti-resonance between the capacitors on the board, lead inductance and capacitance in the chip. But that is not so much a capacitance problem, but a resistance/impedance problem.


    • #3
      this video may help: