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AAT3153

High Efficiency 1X/1.5X/2X Charge Pump For White LED Applications

Analog Technology Inc 

AAT3153

High Efficiency 1X/1.5X/2X Charge Pump

For White LED Applications

Functional Block Diagram

C1+ C1- C2+ C2-

VIN

EN/SET

Soft-Start

Control

1MHz

Oscillator

Voltage

Reference

S2C

Interface

1X, 1.5X and 2X

Charge Pump

D/A

6 x 16 bit

ROM

D/A

D/A

D/A

6 x 16 bit

D/A

ROM

D/A

VOUT

D1

D2

D3

D4

D5

D6

GND

Functional Description

The AAT3153 is a tri-mode load switch (1X) and

high efficiency (1.5X or 2X) charge pump device

intended for white LED backlight applications. To

maximize power conversion efficiency, an internal

sensing circuit monitors the voltage required on

each constant current sink input and sets the load

switch and charge pump modes based on the input

battery voltage and the current sink input voltage.

As the battery discharges over time, the AAT3153

charge pump is enabled when any of the four cur-

rent sink inputs near dropout. The charge pump ini-

tially starts in 1.5X mode. If the charge pump out-

put drops enough for any current source output to

become close to dropout, the charge pump will

automatically transition to 2X mode. The AAT3153

requires only four external components: two 1µF

ceramic capacitors for the charge pump flying

capacitors (C1 and C2), one 1µF ceramic input

capacitor (CIN), and one 0.33µF to 1µF ceramic

charge pump output capacitor (COUT).

The six constant current sink inputs (D1 to D6) can

drive six individual LEDs with a maximum current

of 20mA each. The unused sink inputs must be

connected to VOUT, otherwise the part will operate

only in 2X charge pump mode. The S2Cwire serial

interface enables the AAT3153 and sets the cur-

rent sink magnitudes. S2Cwire addressing allows

independent control of two groups of current sink

input: D1-D4 and D5-D6.

6

3153.2004.10.0.6

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