How to power XIAO ESP32S3 from 5V VIN/VBUS with diode?

Products & Technology XIAO
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Hello,

I’m in the process of designing a WLED carrier-board for the XIAO ESP32S3 attached to a 5V/14A power supply.

I’d like to power the XIAO via its 5V VIN/VBUS pin directly from the PSU.
The support page suggests to use any kind of diode when powering this way, probably as to not feed current back to the PSU when USB is attached?

My 2 questions:

  1. What Vf (forward voltage) is acceptable? My understanding is that the voltage-drop across the diode reduces the voltage for the ESP? Is <1V a good starting-point?

  2. What’s the suggested current-rating for the diode? I would’ve gone with a 1A Schottky?

Thank you very much for your help!

Steve

Reference: Getting started guide (underneath 3rd image)

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Thank you for that.

I looked at the board’s schematics and the datasheets of the 2 ICs and it appears to me that the module is powered off of 5V directly. No diode used.

Or are you suggesting something else? Would you be so kind to elaborate?
My understanding is that 5V gets fed by the USB connector of the Xiao to the charging IC which charges the BAT and feeds the 3V3 regulator. When the power is sourced from the battery the ETA6003 directs current from the battery to the regulator and into the 3V3 of the Xiao?

But I think my question is answered. Since there is no diode to be found, the Xiao can be powered directly from 5V. Kinda curious as why Seeed does not follow their own suggestions in the Wiki?

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somehow it seems to be alot of confusion with regard to powering… as for me i use the expansion boards because i am an experimenter and not a developer the big concern is back feeding power to a computer or sensitive device on the USB

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the diode on the 5v is for reverse protection for the computer or whatever it may be plugged into

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this… it‘s the other way around

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Thank you all for clarifying this.

I have added a Schottky diode with 2A of forward-current to the design. That should suffice I guess.

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Hi, I’m currently trying to figure out if I need a diode before the 5V pin for my circuit, and I’m a bit confused. Is it true you only need one if you plan on using the external power and usb port at the same time?

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i wish someone could explain this in full…

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Hi edo,
If you plan to connect an external power supply and USB at the same time, it is recommended to connect a diode to both for safety. The power will be supplied from the side with a higher voltage, preventing backflow to the side with a lower voltage.
Connecting the outputs of two power supply circuits without diodes may work, but since I do not know the details of the power supply circuits, I recommend that you prioritize safety.

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Hi there,
YES… The diode is only there to protect the device if current try’s to shunt through if you connect both sources Strongest will win and Xiao will hurt the battery charger circuits.
There is a diagram and a pretty complete explanation with current paths for each Scenario on here somewhere. Search the battery threads for Xiao :+1:

HTH
GL :slight_smile: PJ :v:

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@msfujino @PJ_Glasso Thanks for the replies. It’s true, safety is important. I will add the diode anyway in case I ever forget to unplug the power. It’s only a small investment. :slight_smile:

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I need some help please.

I am not sure where does the diode go? Maybe someone has an image?

Is this the same diode mentioned here? (I can’t post links :frowning: )
[WIKI] /xiao_esp32s3_getting_started/#hardware-overview

You can also use this as a voltage input but you must have some sort of diode (schottky, signal, power) between your external power source and this pin with anode to battery, cathode to 5V pin.

That confuses me, does it go between battery pin and the 5V in the corner? I was asuming the diode goes on one wire, e.g on the + wire between that pin and my external power source wire?

OR: does that text assumes the external power source to the 5V pin is a battery? I want to power it from external source AND have a battery soldered on the board (charging from that external source) and with my scenario in mind that above text is confusing.

Maybe that diode “missing” there so that the 5V pin can be used as either output and input?

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Hi there,

And Welcome here…

So the 5V pin on the Xiao is from the USB being plugged in, Hence the diode…Correct : You connect to the 5V pin before your external power. You do understand You can’t have Both #1 if you do it this way.
I get your battery setup though? No charging from the Xiao’s on board Chip Then too, you have that handled separately, (PMIC) :crossed_fingers:

Use the Diode , you should be good to go, after a few reply’s you’ll get enough forum credz to post pic’s links , etc.

HTH
GL :slight_smile: PJ :v:

hit the search too, you’ll find @msfujino’s posts thoroughly address these topics well. :+1:

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Hi @PJ_Glasso thanks for the reply.

I didn’t fully understand … are you saying I can’t supply 5V power to the board on that 5V pin AND have a battery soldered on the board at the same time? E.g similar to how it works when most devices are powered by USB connector. :flushed::anguished:

The wiki saying a diode end towards the battery did asume external power source is a battery, I found that exact same question and answer on an Adafruit forum regarding a different board :face_with_hand_over_mouth: So I need a diode on the line entering the 5V pin.

I will search this forum too, I thought at this point I was close to clarifying my questions here :grimacing:

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Hi there,

So, lol… no you can power it from the 5V pin and an external source You just need to use the diode.

I think the wiki assumes it’s going to be an external battery.
My question was you probably aren’t going to use the Xiao’s on board battery charger, I understand that to be the case from the information you provided.

If you NEVER use the USB port,you can skip it all together. :cowboy_hat_face::v:

HTH
GL​:grin: PJ :v:

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@SeeedUser - I have been using 5V connected directly to the VBus pin (14) and GND (13) of my XIAO ESP32S3 (and others) without any issues. My 5V “power source” limits voltage injected back (eg a diode).

If the battery is low, it gets charged. If I connect USB the voltage from the USB doesn’t affect my 5V power supply other than reduce its current consumption.
This is dependent on the USB voltage that is supplied (in most cases it’s more than my “5V” supply from my solar charger).

5VConnect
5VConnect633×347 36.6 KB

If I don’t use the USB, I don’t include the diode. In any case, the ESP32S3 just chugs along regardless.

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Thanks @grobasoz and @PJ_Glasso I think it’s all clear now :grimacing:

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Sorry, I ran into something else…

For another scenario than above, if I want to power the Xiao ESP32S3 from solar, I have the attached solar board [DFrobot solar lipo charger, I can’t post links yet], charger accepts 4.4V - 6V solar panel input, it charges a 3.7V battery and outputs same voltage as the battery on that other end like in image.

Now to power the Xiao ESP32 board from this solar power source.

  • I assume I can link that output from solar board to the battery pins on the xiao?
  • Is any diode needed for this setup if I still want to ocasionally plug the usb cable to the xiao board usb connector?

Grr, I cannot include images (new user) :frowning:

 -----------------              ---------------
|                 | >>>>>>>>>> |   DF ROBOT   | >>>>>>>   OUTPUT HERE 
| 5V solar panel  |            | LIPO CHARGER |           3.7V - 4.2V
|                 | >>>>>>>>>> |              | >>>>>>>   same as battery
 -----------------              ---------------
                                   |      |
                                   |      |
                                   |      |
                                ---------------
                                |             |
                                |   3.7V bat  |
                                |             |
                                ---------------
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Hi there,

So the problem would be the Charger in the Xiao if you connect the External charger to the Batt terminals and then connect a USB-C it will try to charge the external charger. (problem) Some can act as a Battery eliminator and have the Diodes already. YMMV
:grin:
I know takes a few more posts maybe , but you will get there… :+1:
I have never done it that way, so you’ll be on the bleeding edge, exspect some cuts :crossed_fingers: :sweat_smile:

I have seen a Solar Power Brick (internal Battery) connected to the
USB of the Xiao and that worked pretty well. Cloudy days the Battery kept it going no problem, Normally it’s just on and recharged by 10 am (south florida)
I 'm a purist in that way , I either use a battery connected to Xiao and it handles the charge management or USB-C power brick… Always works. :+1: No diodes, no Shenanigans :grin: :vulcan_salute:

HTH
GL :slight_smile: PJ :v: