We have found that when customers are using a display from another manufacture that has 14 pins and we send them a sample of an exact cross, they find that our displays have 16 pins. There is no difference between the two displays other than the 2 additional pins.
Most displays come with three backlight options.
Option 1: LED
Option 2: EL
Option 3: No backlight
On the PCB, pins 15 and 16 are used to power up the LED or EL backlight.
I do not have a backlight: If you do not use a backlight, there is no need for pins 15 and 16. Some manufactures use a PCB with 14 pins on the displays that have no backlight and 16 pins on displays that have a backlight. This means they carry two different types of PCBs in stock. We find that it lowers the manufacturing cost to manufacture one PCB that has 16 pins. If you do not have a backlight, then pins 15 and 16 are not connected. They are just two holes that were drilled out of the PCB.
I have an LED backlight: If you have an LED backlight, then you need to draw your power from some other location than pins 15 and 16. You have two options.
Option 1: You can draw this power from pins 1 and 2. Note, this is only possible if your LCD voltage is the same as your LED backlight voltage. Some customers may have a 3.3V LCD and a 5V LED. If this is the case, do not draw the LED power from pins 1 and 2.
Option 2: You can draw the power from pins A and K on the side of the PCB.
I have an EL backlight: If you have an EL backlight, then you will have to draw the power from the A and K on the side of the PCB.
