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ADM8839

Charge Pump Regulator

for Color TFT Panels

FUNCTIONAL BLOCK DIAGRAM

OSCILLATOR

CONTROL

LOGIC

TIMING

GENERATOR

SHUTDOWN

CONTROL

DISCHARGE

VOLTAGE

INVERTER

VOLTAGE

TRIPLER

LDO

VOLTAGE

REGULATOR

VOLTAGE

DOUBLER

C1+

C1–

LDO_IN

VOUT

+5VOUT

C2+

C2–

C3+

C3–

+15VOUT

C4+

C4–

–15VOUT

–15V

+15V

+5V

GND

SHDN

LDO_ON/

OFF

DOUBLE

TRIPLE

C5, 2.2 F

C1, 2.2 F

C6, 2.2 F

C7, 2.2 F

C8, 0.22 F

C9, 0.22 F

C2, 0.22 F

C3, 0.22 F

C4, 0.22 F

ADM8839

+5VIN

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.

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

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 is packaged in a 20-lead LFCSP

(lead frame chip scale package).