AAT3143ITP-T1 View Datasheet(PDF) - Advanced Analogic Technologies

Part Name

Description

MFG CO.

AAT3143ITP-T1

High Efficiency 1X/1.5X/2X Charge Pump with PWM Control for White LED Applications

Advanced Analogic Technologies 

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PRODUCT DATASHEET

AAT3143

ChargePumpM High Efficiency 1X/1.5X/2X Charge Pump with PWM Control for White LED Applications

Functional Block Diagram

C1+ C1- C2+ C2-

IN

Soft-Start

Control

1MHz

Oscillator

Voltage

Reference

EN/PWM

EN/PWM

1X/1.5X/2X

Charge Pump

CP

D/A

D1

D/A

D2

D/A

D3

D/A

D4

GND

Functional Description

The AAT3143 is a tri-mode load switch (1X) and high effi-

ciency (1.5X or 2X) charge pump device intended for

white LED backlight applications. To maximize power con-

version efficiency, an internal sensing circuit monitors the

voltage required on each constant current source output

and sets the load switch and charge pump modes based

on the input battery voltage and the current source out-

put voltage. As the battery discharges over time, the

AAT3143 charge pump is enabled when any of the four

current source outputs nears dropout. The charge pump

initially starts in 1.5X mode. If the charge pump output

drops enough for any current source output to become

close to dropout, the charge pump will automatically tran-

sition to 2X mode. The AAT3143 requires only four exter-

nal 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 four constant current source outputs (D1 to D4) can

drive four individual LEDs with a maximum current of

20mA each. The unused source outputs must be con-

nected to GND, otherwise the part will operate only in 2X

charge pump mode. The EN/PWM input allows the user

to control the brightness of the four LEDs by PWMing up

to 50kHz.

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