Powering a device from the Arduino

Other Hardware Motors, Mechanics, Power and CNC
1

I have a question about powering a TFT display from my Arduino Uno, but first another question:

According to the specs, Uno can be powered by supplying VIN pin with DC 7-12 Volts (recommended). But isn't it possible to supply VIN with 5 Volts? If not, why?

Then to the display. My plan is to power it from the 5V output pin of Uno. It's a 2.2" TFT LCD display from Adafruit (see link below). I will not be using backlight, so the display will not drain more than 20-30 mA accoring to specs. But is 30 mA too much for the Uno to deliver to external device?

Link:
https://www.adafruit.com/product/1480

2

The VIN pin is connected to the input pin of the 5V regulator, so VIN needs to be higher then 5V to operate the regulator.

You can download the schmatic of the UNO, could be worthwhile studying it.

3

Using Vin almost nothing can be powered from the 5 volt pin. The 5 volt regulator gets overheated.

4

Using Vin almost nothing can be powered from the 5 volt pin. The 5 volt regulator gets overheated.

OK, but if I power the whole setting (Uno + device) through USB connector, with 5V regulated, then perhaps things will work out? If USB source can deliver let's say 500 mA without problems of course....

5

USB is a much better solution, or providing regulated 5V to the Uno's 5V pin. Forget about the onboard regulator.

6

I am in a good mode, just eaten a god dinner but... Pulling up to 500 mA, from USB, via the 5 volt pin, is not recommended for those tiny board strips.

7

Pulling up to 500 mA, from USB, via the 5 volt pin, is not recommended for those tiny board strips.

Agree, but the Adafruit display device I will use drains 20-30 mA. I am already feeding a basic 16x2 LCD display (with backlight) from the 5V pin without problems. The USB 500 mA is just to be (absolutely) sure the power supply will not breakdown.

8

Do you mean the pin marked 5V out? I read that it's not recommended to feed this pin with input.

9

Could you send a link to where you read such so they can be spanked?

10

https://docs.arduino.cc/learn/electronics/power-pins

Quoting:
Powering your board via the 3V3/5V pins is not recommended, as it can damage your board's voltage regulator.

11

Lets say the 3V3 regulator on my ESP32 is damaged by me supplying the ESP32 with 3V3, which in the last 7 years has not happened yet, does the ESP32 need the 3V3 regulator if I am supplying 3V3 to the board?

12

How is this relavent?