1

Simple spec question I couldn't figure out, what is, practically speaking and ballpark, the maximum wattage of LED you can drive with an ESP32 (I guess about the same as an arduino?).

Conditions:

  • using a boost converter for higher voltage: Yes
  • using ESP32 pin as output and power: Yes
  • use mosfets/external power circuit: no
  • no other load is connected to the ESP32 board

My silly calculation:

  • GPIO allows for 12mA output (source)
  • cheap and small voltage boost elements go to about 9-12V

i.e. (12 milliamperes) * 12 volts = max 0.144 watts.

Is that about right (orders of magnitude)?

4

No. You're way off.

If the output can provide 12mA at 3.3V that equates to (P=VI) 39.6mW. Boosting the voltages does not increase the power. Assuming a 100% efficient boost circuit (which does not exist) you would just be boosting to 12V at 39.6mW - which means (I=P/V) 3.3mA.

You can't magic more power out of thin air - if you could we'd all have "free energy" devices powering everything. Instead we have power supplies or batteries.

And that is what you will need. A source for that extra power to come from.

1
  • That cleared it up for me, thx. The only way to get more light out of an LED with the same power is to get a more energy sufficient LED in the first place (or get more power) Oct 19 '20 at 4:48
0

Technically the maximum power is unlimited however it depends on the driving circuit. With a simple MOSFET a few hundred watts is very feasible however the leds need to be in a series parallel configuration to keep the current reasonable. If you use the higher wattage LEDs you also have to supply a heat sink for them. As you get further into electronics and the associated circuits this will become more apparent. Another way to look at it is a simple spark can burn down a forest if the conditions are correct.

4
  • I think you're answering to "practically speaking and ballpark, the maximum wattage of LED you can drive" and are missing the "with an ESP32". If I understand your answer right this is not very relevant for this question, it's specific for ESP32 (or arduino's). Nevertheless, interesting! Oct 19 '20 at 11:10
  • Depends if the ESP32 is the driver or controlling device, that was not clear to me. Another part of the equation is what is the loading on the other pins and how closer is it to the chip max current rating. There is a lot of information missing.
    – Gil
    Oct 20 '20 at 19:13
  • I updated the question with the missing information, please mention more, then I improve the question Oct 21 '20 at 7:10
  • 1
    As I understand it you have about 3.5V from the ESP32 and 10mA (I would stay under 10) you then have to select a color, for example they have a forward voltage drop, Red 1.6 - 2.1 Violet 2.8 - 4.0; Depending on your color the answer will change. At the high end Violet will draw nothing as your voltage is below threshold. Assuming a Red at 1.6Vf, a 190 Ohm Resistor you will draw 10mA. This gives you answer at 0.01448 watts. Try this calculator: ohmslawcalculator.com/led-resistor-calculator
    – Gil
    Oct 22 '20 at 20:17

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