7.3.4 Programmable VCOM

The V_COM channels of the BUF20800-Q1 can swing to 2V from the positive supply rail while sourcing 50 mA and to 1 V above the negative rail while sinking 50 mA (see Figure 4, typical characteristic Output Voltage vs Output Current). To store the gamma and the V_COM values, an external EEPROM is required. During power-up of the LCD panel, the timing controller can then read the EEPROM and load the values into the BUF20800-Q1 to generate the desired V_COM voltages, as illustrated in Figure 10 and Figure 8. The V_COM channels can be programmed independently from the gamma channels.

Figure 8. BUF20800-Q1 Used for Programmable V_COM