Pico Supply Voltage

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  • Hello all-
    Saw a video where I think it said the maximum supply voltage for the pico is +5v. But scanning the forums I saw folks talking about the pico being able to handle +16v. Then looking at the data sheet (STM32401xD, right...?) it says "... VDD operating voltage range 1.8 V to 3.6 V." Can someone provide a range on what voltage supply the pico can tolerate (and at which pins)?

    Background: I have an industrial control panel housing +12 VDC DIN-rail power supplies and would prefer not to install another just for the Espruino.

    Thank you!
    -Neil

  • The specs say "On-board 3.3v 250mA voltage regulator, accepts voltages from 3.5v to 16v" You can check out the schematics and board files

    Wasn't 100% sure about the pins, but Gordon said in an earlier post:

    The Pico itself will run direct from the car's 12v though (it'll do up
    to 16v, so fine while the engine is running too). Just connect it
    between the VBAT and GND pins (opposite sides of the board to each
    other).

  • Since decent 12V to USB 5V converters are readily available, I would put one in between car battery and Pico. Reason is that - depending on what you drive with the Pico pins and what else you 'hang onto the Pico's .3V output - the Pico onboard voltage regulator may heat up... after all, with 14.4 Volt - typical for a running engine - and a 250mA current you convert 3.7 Watts into heat. If you let the 12V to USB 5V converter do the heavy lifting ('destroying' power / converting power to heat - up to 3.275 Watts), it will only be 0.425 Watts left for the regulator of the Espruino to 'dispose'.

  • Hi - yes, the Pico is fine with up to 16v because of the onboard regulator. It'll be drawing under 40mA as long as you're not powering anything else from the 3.3v line, so the regulator is unlikely to have any problems at 12v.

    As @allObjects says if you're planning on hanging other stuff on the 3.3v line that brings it up to near the regulator's 250mA limit (like an ESP8266 WiFi) then you might want to consider a regulator to bring the volts down to 5v so the poor regulator doesn't heat it too much. It has overtemperature protection, but it might cause the Pico to reboot :)

    Just a note though: You can power the Pico from up to 16v just fine, but the IO pins can only take up to 5V signals in :)

  • It'll be drawing under 40mA...

    This is a good average for high drawing with output pins just driving input pins with only (very) high input impedance of other things.

    If you though drive lower impedance inputs / loads - and LEDs (can) already fall in this category, or even driving other devices' power as done in this application about GPS powered by Espruino pin(s) - you may rethink -and do current budgeting.

    Taking a look at the chip's specs at http://www.espruino.com/datasheets/STM32­F401xD.pdf , section 6.2 Absolute maximum ratings (p. 58+), Table 12. Current characteristics (p. 59), the chip can draw max 160mA, with I/O pins driving capabilities is 25mA, but sink and source by I/O pins combined is not to exceed 120mA (to stay within voltage spec levels for solid high and low).

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Pico Supply Voltage

Posted by Avatar for .Neil @.Neil

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