Before deciding the VEE, we should first know the module's Vop (VDD-VO). Vo is the differential voltage of VDD and VEE. For example, WG12864A. VDD-VO is 9.4V when the temperature is 25 degrees. When the VO reaches 9.4V, the display will be the best. If VDD is 3.3V, the VEE should be at least 6.1V to achieve the best display. But we suggest the VEE should not be just right. It is better to be bigger for 3V. For instance, as above, 6.1V+3V=9.1V.

The connection of the VEE is as follows--