4" TFT LCD display; 5V or 3.3v?

Other Hardware Displays
1

I have a ST7796 based 4" TFT LCD. Its a pretty Generic display.

When Running with 3.3v Vcc (power) the display is very readable but not that bright. I'm controlling it with a 3.3v processor (currently an NodeMCU).

I want to determine if it is safe to run the TFT LCD on 5V while the logic signals are 3.3 volts.

I haven't found a schematic for this board so I will be doing some testing.

Has anyone found a schematic for such a board? Has anyone had experience on such a split power setup?

Thanks
John

2

ANSWERED:

I found what I think it a schematic. This schematic shows a 3.3v regulator for all internal functions. So powering from 5V would only add dissipation to the regulator and NOT increase the current to the back light LEDs.

3

This is not entirely accurate. The regulator always has a difference between the input and output voltage, which can reach 1-1.5V.
By applying 3.3v to the input of the 3v3 regulator, you will get less that 3v3 at the output

4

You are correct (kinda). I didn't want to go into that much detail for this post but you are correct there is a voltage drop across the 3.3V regulator, however by spec its between 100 and 200 mv for this device (XC6206).

5

I agree, it doesn't matter in this case.
I just wanted to warn you :slight_smile:

6

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