BUF20820

BUF20820 SBOS330C − DECEMBER 2005 − REVISED OCTOBER 2006 18-Channel GAMMA VOLTAGE GENERATOR with Two Programmable VCOM Channels FEATURES D 18-CHANNEL GAMMA CORRECTION D 2-CHANNEL PROGRAMMABLE VCOM: 100mA IOUT APPLICATIONS D D D REPLACES RESISTOR-BASED GAMMA SOLUTIONS TFT-LCD REFERENCE DRIVERS DYNAMIC GAMMA CONTROL D D D D D D D ON-CHIP OTP MEMORY 10-BIT RESOLUTION RAIL-TO-RAIL OUTPUT LOW SUPPLY CURRENT: 900µA/ch SUPPLY VOLTAGE: 7V to 18V DIGITAL SUPPLY: 2.0V to 5.5V INDUSTRY-STANDARD, TWO-WIRE INTERFACE: 3.4MHz HIGH-SPEED MODE 4kV HBM, 1kV CDM, 200V MM DESCRIPTION The BUF20820 is a programmable voltage reference generator designed for gamma correction in TFT-LCD panels. It provides 18 programmable outputs for gamma correction and two channels for VCOM adjustment, each with 10-bit resolution. It offers on-chip One-Time Programmable (OTP) memory that allows the user to store the gamma voltages on-chip. This eliminates the need for an external EEPROM. This programmability replaces the traditional, timeconsuming process of changing resistor values to optimize the various gamma voltages and allows designers to determine the correct gamma voltages for a panel very quickly. Required voltage changes can also be easily implemented without hardware changes. The BUF20820 uses TI’s latest, small-geometry analog CMOS process, which makes it a very competitive choice for full production, not just evaluation. Programming of each output occurs through an industrystandard, two-wire seri...