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AAT3171

High Current, High Efficiency Charge Pump with Auto-Timer

Analog Technology Inc 

General Description

The AAT3171 is a high output current, high effi-

ciency, low noise, low profile charge pump DC/DC

converter. The device is ideal for multi-functional

LED photo-flash applications where solution cost,

size, and efficiency are critical.

The AAT3171 is capable of driving a regulated out-

put current up to 800mA. Output current levels can

be easily programmed in 16 steps through

AnalogicTech's Simple Serial Control™ (S2Cwire™)

interface controlled by a single microcontroller

GPIO line. This allows smooth transitions and flexi-

ble adjustment of brightness in flash or other light-

ing modes. The maximum output current can also

be set with an external RSET resistor.

The tri-mode (1X/1.5X/2X) operation of the internal

charge pump offers excellent power efficiency

throughout the output current range for both flash

and movie modes. Combined with a low external

parts count (two 1µF flying capacitors and two small

bypass capacitors at VIN and OUT), the AAT3171 is

ideally suited for small battery-powered applications.

The AAT3171 has a thermal management system to

protect the device in the event of a short-circuit con-

dition at the output pin. Built-in soft-start circuitry pre-

vents excessive inrush current during start-up. The

shutdown feature disconnects the load from VIN and

reduces quiescent current to less than 1µA.

The AAT3171 is available in a Pb-free, thermally-

enhanced 12-pin 3x3mm TDFN package and is spec-

ified over the -40°C to +85°C temperature range.

Typical Application

1µF

AAT3171

High Current, High Efficiency

Charge Pump with Auto-Timer

Features

ChargePump™

• Up to 800mA Output Current

• Tri-Mode 1X/1.5X/2X in Current Mode

• 16 Current Level Steps Set by S2Cwire

• External RSET to Set Maximum Current

• <1µA of Shutdown

• Small Application Circuit

• No Inductors

• Automatic Soft Start

• 12-Pin TDFN 3x3mm Package

• -40°C to +85°C Temperature Range

Applications

• Camcorders

• Camera Phones

• Digital Still Cameras

• PDAs and Notebook PCs

• Smart Phones

1µF

2.7V

to 5.5V

C1+

VIN

CIN

4.7µF

C1- C2+

AAT3171

C2+

OUT

COUT

2.2µF

Flash

LED

EN

0.1µF

EN/SET

CT

GND

FL

RSET

187K

3171.2007.03.1.1

1

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