Cheap eBay TFTs - 5V vs 3V

There's a PDF ("Reading.pdf") that comes with these screens explaining the 5V vs. 3V thing. Trouble is, it's in Chinese. I've just been running it through google translate and the results are surprisingly good.

The three bullet points are:

TFT Power: Screen Power is 2.8-3.3V; remember not to use 5V
(Modules with PCB's have inherited 3V regulator IC, you can enter 5V)

The screen I bought does have a 3V regulator on Vcc so 5V to Vcc is OK.

Backlight power supply (LED pin): 3.2V maximum backlight power (At 3.3V supply can be connected in series for 10 ohm current limiting resistor in series with 100 ohms or 5V Resistance)

I've been connecting it directly to 3.3V, it needs a 10 Ohm resistor. :frowning:

Data port level: theoretically can not let the data port level exceeds 3.3V, if you must IO connection with 5V microcontroller data bus, as tft internal voltage clamp, with
Can be used, but is not always standard. You can do an experiment to test a sample batch
Made product, in order to improve product stability, better use of low-voltage monolithic
Machine or add a level converter IC

So there you have it... "use a low voltage machine or add a level converter IC".

Its a shame they dont add a few 74LCX244's or 74LCX245s and make
these boards 5V tolerant... The 74LCX family are 3.3V powered with 5V
tolerant inputs (but check datasheet just to be sure). I've seen boards
with 74HC245s on so I suspect someone made an attempt to get this
right and the manufacturer substituted a cheaper component...

Currently there are some very cheap SPI 320x240 TFTs using the ILI9341
chip. However I think they are cheap due to no touchscreen.

MarkT:
Its a shame they dont add a few 74LCX244's or 74LCX245s and make
these boards 5V tolerant... The 74LCX family are 3.3V powered with 5V
tolerant inputs (but check datasheet just to be sure). I've seen boards
with 74HC245s on so I suspect someone made an attempt to get this
right and the manufacturer substituted a cheaper component...

Yep. I'm expecting the next batch to be 5V tolerant (as soon as they sell the 10,000 screens from the previous manufacturing run).

MarkT:
Currently there are some very cheap SPI 320x240 TFTs using the ILI9341 chip

Yes, I've got three of them and I"m planning to get some more. :slight_smile:

MarkT:
However I think they are cheap due to no touchscreen.

Is there no suitable-size touch-screen overlay for these? They're a bit too small for a touch interface anyway.

There's hundreds of 3.2" touch panels for a bit more money.