External power to the 5V pin does not work for XIAO ESP32-S3 and XIAO ESP32-C3

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#1

Dear Seeed Studio Team,

please provide a circuit, which allows to connect external power supply 5V DC to the 5V Pin for the XIAO ESP32-S3 and XIAO ESP32-C3 boards.

The mentioned on the wiki pages suggestion to connect the 5V to the board via “…some sort of diode (schottky, signal, power) between your external power source and this pin…” does not work.
The direct connection from 5V external supply to the 5V pin gives the same results like for the solution with the diode.

I have tested above solution on the two XIAO ESP32-S3 boards and three XIAO ESP32-C3 boards.
Boards were connected to 3-7 Analog/digital sensors (INPUT), SPI (device), WiFi, PSRAM (on S3).
I used exact the same external power supply to power the boards in all tests: USB, direct 5V pin, via schottky diode to 5V pin.

Observed board behaviors:

  • when comes to boot process on wifi with setting IP address the board makes restarts in the loop
  • board stops booting when setting WiFi address to the board
  • from time to time board has started but read data at the startup process from PSRAM where not correct

All above disappears at when the board is powered via the USB connector - all boards worked stable.

Solving the above problem opens for me the possibility to use XIAO boards in wider range of applications.

Thank you in advanced.

#2

What kind of external power supply are you using?
When using wireless, a peak current of 350 mA or more is drawn. Can it be supplied by an external power supply?

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#3

sounds like a brownout issue to me… maybe add a power capacitor

#4

we really need a XIAO power management expansion board

#5

Hi there,
SO can You provide a picture of this Apparatus? I would like to verify your assumptions, and if non proprietary please post up the code you are trying using the code tags above “</>”
also as @msfujino inquires , the power supply parameters you are trying
TIA
GL :slight_smile: PJ :v:

#6

it does seem that this is a common complaint that some do not “Accept” power thru the 5V pin… also the question is how low is the threshold voltage to the regulator… how low can you go? I assume it is not a boost converter

#7

I guess one could use an arduino Uno as a 5v power supply for testing

#8

There is a relevant description in the datasheet. I think the input voltage needs to be 3.3V plus the voltage drop of the high-side FET.

100% Duty Cycle Operation Mode
When the voltage of the input source, such as battery, falls and its value is close to the output voltage, the PWM duty cycle (D = VOUT/VIN) increases to near 100%. Eventually the high-side switch remains continuously on to keep the output regulated. Even when the input voltage falls below the output, the high-side switch is turned on to minimize the error.

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