ADM8840

PRELIMINARY TECHNICAL DATA a Charge Pump Regulator & COM Driver for Color TFT Panel ADM8840 Preliminary Technical Data FUNCTIONAL BLOCK DIAGRAM -15V FEATURES Programmable COM Driver to prevent Screen-Burn 3 Voltages (5.0V,15.0V,-15.0V) from one 3V Supply Power Efficiency optimised for use with TFT in mobile phones Low Quiescent Current Low Shutdown Current (<5uA) Shutdown Function APPLICATIONS Handheld Instruments TFT LCD Panels Cellular Phones VOLTAGE INVERTER C4+ C4 0.22 ␮F C9 0.22 ␮ F C4- ADM8840 TRIPLE VOLTAGE TRIPLER DOUBLE +15V C2+ C2 0.22 ␮F C8 0.22 ␮ F C2C3+ C3 0.22 ␮ F C3- OSCILLATOR TIMING GENERATOR 5VIN +5V 5VOUT SHDN C7 2.2 ␮ F SHUTDOWN CONTROL DISCHARGE LDO VOLTAGE REGULATOR VOUT C1+ C6 4.7␮ F CONTROL LOGIC VOLTAGE DOUBLER C1- C1 3.3 ␮F C10 3.3 ␮ F V CC VOLTAGE ADDER C5+ C5 3.3 ␮F C5DAC1_IN DAC1_SD VREF GENERAL DESCRIPTION ADD_OUT The ADM8840 combines a charge pump regulator and a Common Line (COM) driver in a single chip solution for use in TFT LCD’s. The device provides an LCD controller and grayscale DAC supply voltage of 5.0V (±2%), 2 gate drive voltages of +15V and -15V and a COM driver voltage. This COM Driver voltage alternates the polarity of the Common line voltage every line (or every frame) on the display in order to prevent screen-burn occuring over time. The ADM8840 is powered by a single 3.0V supply. The ADM8840 has an internal 100KHz oscillator for driving the charge pumps. The COM Driver section of the ADM884...