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ADM8840

Analog Devices
Part Number ADM8840
Manufacturer Analog Devices
Description Charge Pump Regulator & COM Driver for Color TFT Panel
Published Mar 23, 2005
Detailed Description PRELIMINARY TECHNICAL DATA a Charge Pump Regulator & COM Driver for Color TFT Panel ADM8840 Preliminary Technical Data...
Datasheet PDF File ADM8840 PDF File

ADM8840
ADM8840

Overview
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 ADM8840 can be used to generate the alternate frame or line inversion of the COM line of the LCD panel.
The ADM8840 receives the COM clock from the controller with a frequency up to 10kHz and allows programmable conditioning of its amplitude and centre voltage through the use of on-board DAC’s.
This allows programmable elimination of display flicker caused by the COM inversion.
The COM_OUT amplitude can be programmed from 4.
0V to 7.
0V in steps of 28mV.
The COM_OUT centre voltage can be programmed to 0...


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