CFAG12864B Backlighting

[bgardner]

I have recently purchased a CFAG12864B-TMI-V display with LED backlighting. I have not received the display yet but am currently working on a PCB and the circuitry for the display. I am a little confused about the backlighting schematics in the documentation. Option 1 seems straightforward - wiring directly to the A and K pads on the side of the display through a resistor. My question has to do with Option 2. Do I just need to run my +5 volts to an 8 ohm resistor and then to pin 19? Are pin 19 and the A pad internally collected on the LCD? If they are, then I assume pin 20 and pad K are also connected.

Thanks,

Bob Gardner

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[CF Support]

By default pins 19 and 20 are connected to A and K through 0 ohm resistors. If you calculate the value of the dropping resistor and find it in SMT, just remove A or K's resistor and replace it with the appropriate dropping resistor for the backlight.

 

[bgardner]

Thanks for the quick reply. I think I will leave the 0 ohm resistors in place and just provide my 5 volts through an 8 ohm or appropriately sized resistor to pin 19.

Thanks again,

Bob