Vo (operating voltage)

[huyvo]

hello
is it safe to tie pin 3 (Vo) of the CFAG1286B-WGH-N to
ground or 5volts?
thanks
Huy

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[CF Tech]

It would be safe , but pointless to do either.

Vlcd for the CFAG12864B-WGH-N is specified at typical of 8.1v typical.

Since Vlcd = Vcc - Vo, and assuming that Vcc = 5v, then Vo must be -3.1 in order to make Vlcd be 8.1v.

So you really need to have Vo at around -3v in order to see anything on the display.

Vlcd for this display is rated from 7.1v to 9.1v, so ideally you would want a circuit connected to Vo that allows easy adjustment between -2.1 and -4.1.

 

[huyvo]

sample code (again)

hello,
thank you for clarifying about the voltage level for Vo.
A few days ago, I asked for some sample code to control the
CFAG12864BW-GHN. Unfornately, I had to reinstall my machine and lost that code. Can you please send or post that code again.
Thank you very much.
huy

 

[CF Support]

YGM.

 

[huyvo]

hello,
last time i believed i was able to click on the arrow on the right
hand corner and get to the code. somehow i was not
able to get the code this time
huy

 

[huyvo]

hi
I think i finally got the code. Thank you!
huy

 

[pericolo]

Hello, i have a CFAH4002A-YYH-JP. But i have a similar question about Vo. If i put Vcc = 5V, and Ground = 0v, so PIN3 (Vo) must be 0v? Because in datasheet i read :
－
supply Voltage For LCD VDD-V0 4.5 V (Typical)
－


So i have 5V (5v - 0v)

am i wrong?

Thank you very much

 

[cosmicvoid]

You are correct. But a 5v Vlcd may make the display a bit dark. You should have Vo be adjustable from 0v to about 2v (or 5v, as shown in the data sheet), by using a potentiometer, as shown. Then you can optimize the contrast setting.