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Decoupling Capacitor Selection
Sakib816 , 05-01-2025, 04:22 PM
What should be the value of the decoupling capacitors placed on the power supply pin of any IC? In some cases, it is seen that there are multiple decoupling capacitors in parallel on the VDD pin of an IC. So how many capacitors should be placed in parallel?Besides, for any buck converter or LDO , what should be the value of input and output decoupling capacitor ?
SirJames , 05-01-2025, 05:52 PM
Golden rule says 100 nF per VDD pin but its always best to check datasheet of every IC to confirm. Sometimes they dont specify exact value so I use 100 nF there.Using 2 or 3 decoupling capacitors to cover whole spectrum of noise is myth from old times. Its been debunked some time ago but many engineers still believe it and even teach it to others.As for voltage regulators, their datasheet should consists this information.
QDrives , 05-01-2025, 10:52 PM
https://www.signalintegrityjournal.com/articles/1589-the-myth-of-three-capacitor-valuesIt all depends on the PDN...As for the voltage regulator, make sure that the capacitance and ESR is within range.
Robert Feranec , 05-06-2025, 10:27 AM
This may also help https://youtu.be/ARwBwHZESOY
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