AS3683

1A Backlight and Camera LED Power Charge Pump

Product Brief

© 1997-2005, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.

www.austriamicrosystems.com

Revision 1.0

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1 General Description

The AS3683 is a low-noise, high-current 1A charge

pump designed for camera flash LEDs and LCD back-

lighting applications. The current sinks are capable of

driving up to 960mA of load current.

The AS3683 integrates two independent current source

purpose LEDs are controlled individually and can be

used for backlighting, but also in support of an RGB fun-

light or a movie indicator lamp. To meet high-flash cur-

rent requirements (up to 960mA), both current source

The AS3683 utilizes austriamicrosystems's patent-pend-

ing Intelligent Adaptive Mode Setting (IAMS) to switch

between 1:1, 1:1.5, and 1: 2 modes. In combination with

very-low-drop-out current sinks, the device achieves

high efficiency over the full single-cell Li+ battery voltage

range. The charge pump operates at a fixed frequency

of 1MHz allowing for tiny external components and its

design ensures low EMI and low input-ripple.

The ultra-flexible brightness control scheme allows for

simple adaptation of the device to different system archi-

tectures.

interface. In these modes the LED brightness, flash

duration, GPIOs and various charge pump states are

controlled by internal register settings. The GPIO pins

can act as programmable input or output pins and can

also be set to trigger preview and flash light directly by a

camera module.

In Hardflash mode the LED brightness is controlled by

the Enable pins. These programming pins can be used

as simple enable pins, or as PWM input, again offering

ample flexibility for setting the LED brightness.

2 Key Features

!

High-Power 1A Charge Pump

- 1:1, 1:1.5, and 1:2 Intelligent Adaptive Mode Set-

ting (IAMS)

- Efficiency up to 95%

- Soft Start to Reduce Inrush Current

- Low-Noise Constant-Frequency Operation

!

Current Sinks

- Up to 960mA Pulsed Flash Current

- Programmable: 0 to 160mA, 0.625mA Resolution

!

Flexible Brightness Control

- Three 0 to 160mA LEDs

!

2 Operating Modes

- Hardflash Mode (Dedicated Control Pins)

!

2 General Purpose Inputs/Outputs in Softflash Mode

- Digital Input, Output, and Tristate

- Programmable Pull-Up and Pull-Down

- Strobe Pin can be used for Camera Flash Control

!

LED Disconnect in Shutdown

!

Open LED Detection

!

Low Stand-By Current (6µA), Interface Fully

Operating

!

Low Shut-Down Current (0.2µA)

!

Wide Battery Supply Range: 3.0 to 5.5V

!

Thermal Protection

!

24-Pin, Small Form-Factor QFN Package

- 4 x 4 x 0.85mm, 0.5mm Pitch

- Enhanced Thermal Characteristics

3 Application

Lighting management for cameras, mobile telephones,

PDAs, and other 1-cell Li+ or 3-cell NiMH powered

devices

.