ESP32 WROOM32 on USB + Ext 5V on Vin

deepakt
Posts: 24
Joined: Tue Feb 26, 2019 12:23 pm

ESP32 WROOM32 on USB + Ext 5V on Vin

Postby deepakt » Sun Mar 03, 2019 5:59 pm

ESP'ians!

I am developing a product and I'm planning use an Ext 5V power supply for the board. Now there will be situations where I'll need the external 5V power supply (to supply 5V to some other components as well) on the Vin port, as well as USB connected to a device (Laptop). I want to know whether it an Ext 5V power supply on Vin port + USB connection at the same time, is a safe configuration? If not, is there anything I can do to combine the two power sources safely?

Thanks a ton in advance!

Regards,
Deepak

AshIsPurestWhite
Posts: 7
Joined: Tue Dec 11, 2018 3:09 am

Re: ESP32 WROOM32 on USB + Ext 5V on Vin

Postby AshIsPurestWhite » Mon Mar 04, 2019 7:05 am

if you connect EXT 5V and USB VBUS directly, there will be current flowing between EXT 5V and USB, since the voltage levels of these two power supply may be different(e.g. EXT 5V is 5.1V, while USB VBUS is 4.8V). And this current may damage either EXT 5V or USB.
You can add a diode for each the power lines before connecting them together.
Also, you can cut off one power supply using a PMOS transistor when the other power supply plug in.

deepakt
Posts: 24
Joined: Tue Feb 26, 2019 12:23 pm

Re: ESP32 WROOM32 on USB + Ext 5V on Vin

Postby deepakt » Mon Mar 04, 2019 4:13 pm

I was thinking of the same, but wanted to check if there's any inbuilt way of achieving this. I'll see what best I can do.

Thanks!
Regards,
Deepak

jcxiot
Posts: 1
Joined: Wed Mar 11, 2020 2:18 pm

Re: ESP32 WROOM32 on USB + Ext 5V on Vin

Postby jcxiot » Wed Mar 11, 2020 2:24 pm

deepakt wrote:
Sun Mar 03, 2019 5:59 pm
ESP'ians!

I am developing a product and I'm planning use an Ext 5V power supply for the board. Now there will be situations where I'll need the external 5V power supply (to supply 5V to some other components as well) on the Vin port, as well as USB connected to a device (Laptop). I want to know whether it an Ext 5V power supply on Vin port + USB connection at the same time, is a safe configuration? If not, is there anything I can do to combine the two power sources safely?

Hi, Re. above, yes you can cannot ext 5V whilst usb power active.
If you look at the schematic you will see a diode ( BAT760 ) which will block reverse currents!
Email me if you want a pic of the part of the schematic I refer too.

rustycage55
Posts: 1
Joined: Thu May 20, 2021 5:08 pm

Re: ESP32 WROOM32 on USB + Ext 5V on Vin

Postby rustycage55 » Thu May 20, 2021 6:32 pm

AshIsPurestWhite wrote:
Mon Mar 04, 2019 7:05 am
if you connect EXT 5V and USB VBUS directly, there will be current flowing between EXT 5V and USB, since the voltage levels of these two power supply may be different(e.g. EXT 5V is 5.1V, while USB VBUS is 4.8V). And this current may damage either EXT 5V or USB.
You can add a diode for each the power lines before connecting them together.
Also, you can cut off one power supply using a PMOS transistor when the other power supply plug in.
Hello, noob question here. What do you mean when you say

"You can add a diode for each the power lines before connecting them together."

I´m making a project using esp32, WS2812B led strip and 5v 5amp PS, i need the usb plugged-in sometimes and sometimes unplugged, should i place the Diode between the PS and the Vin pin, right? should i place it anywhere else?

Thanks a lot for your time!

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