ESP32-DevkitC V4 LED allways on

inheriterik
Posts: 1
Joined: Thu Dec 12, 2019 2:39 pm

ESP32-DevkitC V4 LED allways on

Postby inheriterik » Thu Dec 12, 2019 2:53 pm

Hello everybody!

On my ESP32-DevkitC V4 the LED that is attached to the PCB is always ON.

According to the docs "5V Power On LED" is described as "Turns on when the USB or an external 5V power supply is connected to the board." In my case though it is ON even when powered by 3.3V pin. In the schematics https://dl.espressif.com/dl/schematics/ ... v4-sch.pdf it also looks like there should be no current through LED (according to my limited knowledge).

Details: only 3v3 and GND pins are connected to the lab source set to 3.5V and 500mA. Inside is simple program that triggers deep sleep for 5 secs and then wakes up. It draws 3mA in deep sleep mode (for the LED I hope as I would like to see uA currents with this board) and 42mA in normal mode.

Am I missing something?
Thanks :)

ESP_Sprite
Posts: 3879
Joined: Thu Nov 26, 2015 4:08 am

Re: ESP32-DevkitC V4 LED allways on

Postby ESP_Sprite » Fri Dec 13, 2019 1:30 am

I'd say the AMS1117 is your culprit. The datasheet talks about an internal diode between the output and the input; that would backfeed the 5V line with 3.3V if you only power it via 3.3V.

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