AAT3124(2003) Просмотр технического описания (PDF) - Advanced Analogic Technologies

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AAT3124
(Rev.:2003)

High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications

Advanced Analogic Technologies 

AAT3123/4

High Efficiency 1X/1.5X Fractional Charge

Pump for White LED Applications

General Description

The AAT3123/24 is a low noise, constant frequen-

cy charge pump DC/DC converter that uses a dual

mode Load Switch (1X) and fractional (1.5X) con-

version to maximize efficiency for White LED appli-

cations. The device can be used to produce current

levels up to 20mA to drive up to 6 LEDs from a

2.7V to 5.5V input. Outputs may be operated indi-

vidually or paralleled for driving higher-current

LEDs. Low external parts counts (two 1µF flying

capacitors and two small 1µF capacitors at VIN,

and OUT) make the AAT3123/24 ideally suited for

small battery-powered applications.

AnalogicTech™’s Simple Serial Control™

(S2Cwire™) interface is used to enable, disable

and set the LED drive current with a 32 level loga-

rithmic scale LED brightness control. The

AAT3123/24 has a thermal management system to

protect the device in the event of a short circuit

condition at the output pin. Built-in soft-start circuit-

ry prevents excessive inrush current during start-

up. A high charge pump switching frequency

enables the use of very small external capacitors.

A low current shutdown feature disconnects the

load from VIN and reduces quiescent current to less

than 1µA. The AAT3123 is available in very small

12 pin TSOPJW package. The six output AAT3124

is available in a 16 pin 4x4mm QFN package.

Features

ChargePump™

• Dual Mode 1x and 1.5x Charge Pump for

Maximum Efficiency

• Drives Low-VF & High-VF Type LEDs

• Up to 6 20mA Outputs

• 32 Position Logarithmic Scale with Digital

Control

• Simple Serial Control™ (S2Cwire™) interface

• Low Noise Constant Frequency Operation

• 1MHz Switching Frequency

• Small Application Circuit

• Regulated Output Current

• Automatic Soft-Start

• VIN Range: 2.7V to 5.5V

• No Inductors

• Iq < 1µA in Shutdown

• Temperature Range -40 to 85°C.

• 16 pin 4x4 QFN package (AAT3124)

• 12 pin TSOPJW-12 package (AAT3123)

Applications

• White LED Backlighting

• White Photo-Flash for DSCs

• Color (RGB) Lighting

• Programmable Current Source

Typical Application

VBATTERY

VIN

C1+

CIN

COUT

1µF

1µF

EN/SET

VOUT

C1-

C2+

AAT3124

C2-

D1

D2

D3

D4

EN/SET

D5

D6

GND

C1

1µF

C2

1µF

D6

D5

D4

D3

D2

D1

3123.2003.09.1.1

1

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