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CFAG128128A Connexion issue


New member
I am working on a project to create a graphic function controller with a PIC 18F and a CFAG128128A display.
The problem is that I can't figure out how to connect it to the power supply.

Apparently there is a supply for the logic (5 V) and a supply for the LCD, for the backlight I suppose.
However, the datasheet is extremly unclear concerning the supply voltage for the LCD.

What is Vo? What do I connect to pin no 4?
And what on earth is the -16v output for pin no 20???

If anybody could answer me very quickly, I'd be extremely grateful!
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Last edited:


New member
Sure, Vo(V0) is for contrast adjustment (it could be very sensitive)

pin 21 - backlight (+5V)
pin 22 - backlight (GND)


CF Support

The datasheets have been updated / corrected to reflect the pin functions in the mechanical drawing.

You can find the updated datasheets here.

CF Tech

Do Not Connect +5v Directly To The Backlight !!

. . .
pin 21 - backlight (+5V)
pin 22 - backlight (GND)
This is a dangerous way to put it. This description would be better:

Pin 21 = LED A (anode / positive)
Pin 22 = LED K (cathode / negative)

Connecting +5v and ground will damage the backlight. You need a current limiting resistor as follows:

CFAG128128A-STI-TZ ==> Rlimit = (5v-3.5v)/0.096A = 16 ohm minimum

CFAG128128A-TMI-TZ ==> Rlimit = (5v-3.5v)/0.120A = 13 ohm minimum

CFAG128128A-YYH-TZ ==> Rlimit = (5v-4.2v)/0.500A = 1.6 ohm minimum

. . . Here is a post that explains how to connect the backlight:



New member
Thank you!

Thank you very much for replying so quickly, you've been extremely helpful!