ADM8839

Features:

3 Voltages (+5 V, +15 V, -15 V) fro 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


Application

Hand-held Instruments
TFT LCD Panels
Cellular Phones


Pinout




Specifications

(T_A = 25°,C, unless otherwise noted.
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . .-0.3 V to +6.0
Input Voltage on Digital Inputs . . . . . . . . . . ..-0.3 V to +6.0
Output Short-Circuit Duration to GND . . . . . . . . . . . . .10 sec
Output Voltage
   +5 V Output . . . . . . . . . . . . . . . . . . . . . . . . . . .0 V to 7.0 V
   -15 V Output . . . . . . . . . . . . . . . . . . . . .. . .-17 V to +0.3V
   +15 V Output . . . . . . . . . . . . . . . . . . . . . ..-0.3 V to +17 V
Operating Temperature Range . . . . . . . . . .  .-40 to +85
Power Dissipation . . . . . . . . . . . . . . . . . . . .  . . . . . . . .50 mW
Storage Temperature Range . . . . . . . . . . . . .-65to +150
ESD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .Class I


Description

The ADM8839 is a charge pump regulator used for color thin film transistor (TFT) liquid crystal displays (LCDs). Using charge pump technology, ADM8839 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 ar 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 (R)C15 V outputs, if required by the user .

The ADM8839 has a power save shutdown feature. The 5 Voutput consumes the most power, so power efficiency is also maximized on this output with an oscillator enabling scheme(Green Idle^TM). This effectively senses the loadcurrent 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 is packaged in a 20-lead LFCSP (lead frame chip scale package).