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!
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
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!