Question about reset RC and boot network

n47h4n
Posts: 11
Joined: Sun Mar 05, 2023 10:59 am

Question about reset RC and boot network

Postby n47h4n » Sat Apr 22, 2023 2:35 pm

Hi,

In Espressif documentations (ESP32-S2, S3, C3) it is adviced to use a RC network made of 10k resistor to VCC and 1uF capacitor to GND.
But in most schematics a 0.1uF capacitor is used.
My question is what value one must use?

Same for "boot" pin. 1k resistor and 10pF capacitor. Is that good?

Thanks for your responses.

ESP_Sprite
Posts: 9589
Joined: Thu Nov 26, 2015 4:08 am

Re: Question about reset RC and boot network

Postby ESP_Sprite » Sun Apr 23, 2023 2:14 am

For the reset, it depends on your power setup (slow rising power needs a larger capacitor) as well as the way you program the board: if you use the two-transistor auto-download mode circuit, some PCs/OSses need a slower reset requiring a larger capacitor. If you use internal USB for programming and have a fast-rising power supply (e.g. USB with a LDO with not too much decoupling capacitance), an 0.1uF + 10K will suffice.

No idea what that 10pF is good for (especially as the switch probably has a parasitic capacitance in the same order of magnitude), where do you see that?

n47h4n
Posts: 11
Joined: Sun Mar 05, 2023 10:59 am

[SOLVED] Question about reset RC and boot network

Postby n47h4n » Sun Apr 23, 2023 6:09 am

@ESP_Sprite thanks

About the 10pF capacitor, I saw it on this schematic https://files.seeedstudio.com/wiki/XIAO ... C3-SCH.pdf
I think you are right. It must be there to avoid parasitic bounces on the button.

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