ESP32 Forum

Hello,
i'm reasoning about a little problem that i'm facing using my ESP32-PICO-KIT v.4.1 from Espressif. I'm powering the board from 3.3V pin and i'm getting the Power ON Led turned on (red light).

In the getting started page:
https://docs.espressif.com/projects/esp ... -documents
i can read what follows:

5V Power On LED
This light emitting diode lits when the USB or an external 5V power supply is applied to the board. For details see schematic in Related Documents.

I even watched the schematic (https://dl.espressif.com/dl/schematics/ ... ematic.pdf) and i don't understand how it can turn on when only 3.3V is plugged in. Is this a wanted effect?

Ok, i can just unsolder it, but i really would like to understand what i am missing.

Thanks,
Frax

Assuming you don't have any USB cables attached, I'd say leak current through U1.

Hi permal,
of course there is no usb cable attached. If we consider the schematics of che circuit it has to be the leaking you suppose, but i'm wondering why this has been not predicted in the circuit (the leaking could be easily managed inserting a diode before the voltage regulator) or not corrected in the datasheet that calls the led "5V Power on led" and even explain that led powers on with EXT 5V or USB.

Considering the possibility to use the ESP32 for low power projects, paying attention to such trivial things should be a golden rule. Even if is true that led can be unsoldered you have that 1) in projects with a good number of device this matter becomes annoying and 2) not everyone that want to plays with ESP32 has a soldering station to unsolder the led.

Has anyone other thinking about this?

Thank you

but i'm wondering why this has been not predicted in the circuit (the leaking could be easily managed inserting a diode before the voltage regulator) or not corrected in the datasheet that calls the led "5V Power on led" and even explain that led powers on with EXT 5V or USB.

I am sure it was predicted, just deemed not important to add the extra part for cost reasons.

Considering the possibility to use the ESP32 for low power projects, paying attention to such trivial things should be a golden rule.

If one were to take every trivial thing into account then this low cost kit would cost far more money. For instance, they would have to add protection diodes to the USB lines to prevent transients spikes on the line, or TVS diodes on the power rails to prevent over and reverse voltages. There is just a myriad of things thing they would have to add raising the cost way to high.

Even if is true that led can be unsoldered you have that 1) in projects with a good number of device this matter becomes annoying and 2) not everyone that want to plays with ESP32 has a soldering station to unsolder the led.

Not trying to sound rude. But if one does not have at least a soldering iron, or meter in their tool kit, how serious can they be in developing something anyway. You have to keep in mind the the ESP32-PICO-KIT is primary meant for you to evaluate the ESP32 module itself quickly, and incorporate that module into your own design, and not the ESP32-PICO-KIT into your design.

Leaving aside the things you said about all the protections could be added, what i'm arguing about is the incongruency between what i read on the docs and what i obtain. You say they predicted it and the reason for certain choices is the cost? Ok, i can understand that, but then why the docs says that the LED should be ON just with external 5V or USB? This is what i'm arguing about, as i well explained in the previous post and you even quoted:

but i'm wondering why this has been not predicted in the circuit (the leaking could be easily managed inserting a diode before the voltage regulator) OR not corrected in the datasheet that calls the led "5V Power on led" and even explain that led powers on with EXT 5V or USB.

Now: the problem is the cost of a diode? Ok, no problem with that, just correct the docs.

Thank you for your opinion,
Frax

I think your looking at the "Getting Started Guide" as a technical data sheet. In those cases things have to be spelled out to the letter.
The "Getting Started Guide" is just simply giving a quick reference to things on the board.

In my opinion this should be corrected. The fact that is a "getting started guide" doesn't mean he can't be improved. By the way, this is just my opinion.

Frax

Hi guys,
Thank you for brining this issue out and sorry for confusion.
I will get the guide corrected.