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ADM8839

Analog Devices
Part Number ADM8839
Manufacturer Analog Devices
Description Charge Pump Regulator for Color TFT Panels
Published Mar 23, 2005
Detailed Description Charge Pump Regulator for Color TFT Panels ADM8839 FEATURES 3 Voltages (+5 V, +15 V, –15 V) from a Single 3 V Supply Pow...
Datasheet PDF File ADM8839 PDF File

ADM8839
ADM8839

Overview
Charge Pump Regulator for Color TFT Panels ADM8839 FEATURES 3 Voltages (+5 V, +15 V, –15 V) from a Single 3 V Supply Power Efficiency Optimized for Use with TFT in Mobile Phones Low Quiescent Current Low Shutdown Current (<5 ␮A) Shutdown Function Option to Use External LDO APPLICATIONS Hand-held Instruments TFT LCD Panels Cellular Phones FUNCTIONAL BLOCK DIAGRAM C5, 2.
2␮F VCC ADM8839 C1+ VOLTAGE DOUBLER C1– C1, 2.
2␮F VOUT LDO_IN OSCILLATOR LDO VOLTAGE REGULATOR C6, 2.
2␮F +5VOUT +5VIN C2+ C2– C3+ C3– C3, 0.
22␮F +15V C8, 0.
22␮F C4, 0.
22␮F LDO_ON/OFF CONTROL LOGIC +5V C7, 2.
2␮F DOUBLE VOLTAGE TRIPLER TRIPLE TIMING GENERATOR C2, 0.
22␮F +15VOUT C4+ SHDN SHUTDOWN CONTROL DISCHARGE VOLTAGE INVERTER C4– –15VOUT GND –15V C9, 0.
22␮F GENERAL DESCRIPTION The ADM8839 is a charge pump regulator used for color thin film transistor (TFT) liquid crystal displays (LCDs).
Using charge pump technology, the device can be used to generate three voltages (+5 V ± 2%, +15 V, –15 V) from a single 3 V supply.
These voltages are then used to provide supplies for the LCD controller (5 V) and the gate drives for the transistors in the panel (+15 V and –15 V).
Only a few external capacitors are needed for the charge pumps.
An efficient low dropout (LDO) voltage regulator ensures that the power efficiency is high and provides a low ripple 5 V output.
This LDO can be shut down and an external LDO can be used to regulate the 5 V doubler output and drive the input to the charge pump section that generates the +15 V and –15 V outputs, if required by the user.
The ADM8839 has a power save shutdown feature.
The 5 V output consumes the most power, so power efficiency is also maximized on this output with an oscillator enabling scheme (Green Idle™).
This effectively senses the load current that is flowing and turns on the charge pump only when charge needs to be delivered to the 5 V pump doubler output.
The ADM8839 is fabricated using CMOS technology for minimal power consumption.
The part i...


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