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I am trying to design a "custom" design for ESP32 based on the ESP32-pico-kit_v4.1_20180314_en.

Schematic: ESP32-Pico-kit V4.1

BOM: ESP32-Pico-kit V4.1

Why do capacitors C2,C4 and C15 have the same capacitance but different voltage ratings?

Is that for saving some space since the 6.3V is 0402 instead of 0603 and probably being cheaper or it does it have to do with ESR?

Regarding the resistors, could I replace them all with 0603 since 0402 is hard for me to solder?

By replacing them, is there any chance that the different package would make ESP32 not to work properly? If yes, why?

If ESP32 would work properly, are there any other cases where replacing with higher/smaller package would cause something not to work?

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    \$\begingroup\$ I would replace all with 0603 25 V to facilitate procurement and production. \$\endgroup\$
    – winny
    Commented Feb 15, 2021 at 15:13

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C4 is exposed to the externally driven EXT_5V input. I suppose that the designer wanted to ensure that an input higher than 5V would not damage the capacitor. Note that the regulator AMS1117 is capable of handling a 13.8V input.

C2 is only exposed to the regulated 3.3V output but it is likely picked to match C4 and reduce the number of different parts in the design. It's perfectly OK to use a capacitor with a higher rated voltage in place of a lower voltage one.

C15 sees only the 3.3V regulated output and doesn't need to be any higher voltage than that. Why did they pick 6.3? Probably because they wanted some margin on the spec or perhaps just had those readily available.

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  • \$\begingroup\$ for a 3.3V supply 6.3V is the standard WV. The next lower value is 4V which is insufficiently derated for DC biasing. \$\endgroup\$ Commented Feb 15, 2021 at 12:23
  • \$\begingroup\$ thank you, in order the reduce the number of different parts then I can use only the C4 for C2 and C15 etc right? I have seen some people saying to be careful about the 1117 linear regulator choosing larger packages which usually mean higher ESR \$\endgroup\$
    – Kris
    Commented Feb 15, 2021 at 12:27
  • \$\begingroup\$ You'll want to study the 1117 datasheet and make sure you follow the manufacturer's recommendations for parameters such as ESR for the caps. \$\endgroup\$
    – jwh20
    Commented Feb 15, 2021 at 12:38

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