EN pin design review for my ESP32-S3 WROOM-1U module board.

Thanos
Posts: 3
Joined: Tue Nov 01, 2022 7:07 am

EN pin design review for my ESP32-S3 WROOM-1U module board.

Postby Thanos » Sun May 28, 2023 4:11 pm

Hello,
I am designing an ESP32-S3 module based board which has some space constraints. So,i have used external circuit with reference to some designs which i found online which has an 10k resistor and an 1uF capacitor. I would like to know if the EN pin circuit has been designed properly. Please kindly check the attached file and let me know about it

ESP_Sprite
Posts: 9713
Joined: Thu Nov 26, 2015 4:08 am

Re: EN pin design review for my ESP32-S3 WROOM-1U module board.

Postby ESP_Sprite » Mon May 29, 2023 6:06 am

Generally, that RC network is a balance between startup time and power supply behaviour. With that said, the 10K/1uF combo works fine for most cases. I can't check your schematic as it wasn't attached.

Thanos
Posts: 3
Joined: Tue Nov 01, 2022 7:07 am

Re: EN pin design review for my ESP32-S3 WROOM-1U module board.

Postby Thanos » Tue May 30, 2023 7:32 am

Hello, thanks for your response. Please check this image. Is it ok to put 1K resistor for the boot button?
Attachments
IMG-20230530-WA0002.jpg
IMG-20230530-WA0002.jpg (67.86 KiB) Viewed 1371 times

ESP_Sprite
Posts: 9713
Joined: Thu Nov 26, 2015 4:08 am

Re: EN pin design review for my ESP32-S3 WROOM-1U module board.

Postby ESP_Sprite » Wed May 31, 2023 7:34 am

Sure. Here's how you figure that out. The datasheet says that IO0 has a weak internal pull-up, and that the value of those internal pull-ups generally is 45K. That means with the button pressed, the voltage on IO0 will be defined by the resistor divider comprised of the weak internal pull-up to 3.3V and the external 1K to ground. This means the voltage will be around (3.3V*1K/(1K+45K))=0.07V. This is below the low-level input voltage threshold for a digital pin, which is 0.25*3.3V=0.825V, so it will be successfully detected as a low value.

(Or you just spitball it by saying 1K is a lot less than the 45K, so it'll generally 'override' the 45K.)

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