AAT3152(2005) Просмотр технического описания (PDF) - Advanced Analogic Technologies

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AAT3152
(Rev.:2005)

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

Advanced Analogic Technologies 

AAT3152

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

For White LED Applications

General Description

The AAT3152 is a low noise, constant frequency

charge pump DC/DC converter that uses a tri-mode

load switch (1X), fractional (1.5X), and doubling (2X)

conversion to maximize efficiency for white LED

applications. The AAT3152 is capable of driving

four-channel LEDs from a 2.7V to 5.5V input. The

current sinks may be operated individually or in par-

allel for driving higher-current LEDs. A low external

parts count (two 1µF flying capacitors and two small

1µF capacitors at VIN and VOUT) makes this part ide-

ally suited for small, battery-powered applications.

AnalogicTech's S2Cwire™ (Simple Serial Control™)

serial digital input is used to enable, disable, and

set current for each LED with eight settings (20mA

down to 50µA) including main/sub-display group

control. The AAT3152 consumes extremely low cur-

rent internally (50µA typical) at light load for opti-

mized efficiency.

Each output of the AAT3152 is equipped with built-

in protection for VOUT short-circuit and auto-disable

for load short-circuit conditions. Built-in soft-start

circuitry prevents excessive inrush current during

start-up. A low current shutdown feature discon-

nects the load from VIN and reduces quiescent cur-

rent to less than 1µA.

The AAT3152 is available in a Pb-free, space-sav-

ing, thermally-enhanced 12-pin 3x3mm TDFN

package.

Typical Application

Features

ChargePump™

• VIN Range: 2.7V to 5.5V

• Fully Programmable Current with Single Wire

— Eight-Step Current: 20mA to 50µA

— Individual Main-Sub Group Control

— Low IQ (50µA) at Light Load

• Tri-Mode 1X, 1.5X, and 2X Charge Pump for

Maximum Efficiency and VF Coverage

• Drives 1-4 Channels of LEDs

• No Inductors, Low Noise Operation

• 1MHz Constant Switching Frequency

• Small Application Circuit

• Built-In Thermal Protection

• Built-In Auto-Disable for Short-Circuit

• Automatic Soft Start

• IQ <1µA in Shutdown

• Thermally-Enhanced 3x3mm 12-Pin TDFN

Package

Applications

• Color (RGB) Lighting

• Programmable Current Sinks

• White LED Backlighting

• White Photo Flash for Digital Still Cameras

2.7V to 5.5V

VIN

C1+

CIN

1µF

C1-

C2+

AAT3152

C2-

VOUT

EN/SET

EN/SET

D1

D2

D3

D4

GND

C1

1µF

C2

1µF

D1 D2 D3 D4

COUT

1µF

3152.2005.08.1.2

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