MAX8798

19-0971; Rev 0; 9/07 Internal-Switch Boost Regulator with Integrated 3-Channel Scan Driver for TFT LCDs General Description The MAX8798 includes a high-performance, step-up regulator; a high-speed operational amplifier; a digitally adjustable VCOM calibration device with nonvolatile memory and an I2C interface; and a high-voltage, levelshifting scan driver. The device is optimized for thin-film transistor (TFT) liquid-crystal display (LCD) applications. The step-up DC-DC converter provides the regulated supply voltage for panel source driver ICs. The high switching frequency allows the use of ultra-small inductors and ceramic capacitors. The current-mode control architecture provides fast transient response to pulsed loads typical of source driver loads. The step-up regulator features soft-start and current limit. The high-current operational amplifier is designed to drive the LCD backplane (VCOM). The amplifier features high output current (±150mA), fast slew rate (45V/µs), wide bandwidth (20MHz), and rail-to-rail inputs and outputs. The programmable VCOM calibrator is externally attached to the VCOM amplifier’s resistive voltage-divider and sinks a programmable current to adjust the VCOM output-voltage level. An internal 7-bit digital-to-analog converter (DAC) controls the sink current. The DAC is ratiometric relative to BOOST and is guaranteed to be monotonic over all operating conditions. The calibrator IC includes an EEPROM to store the desired VCOM voltage level. The 2...