AS3683 AMSCO

Document overview

Manufacturer or author: Provided By digicamel.com
PDF pages: 4

Technical content

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 1 - 4

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 blocks for driving a single flash LED (CURR 11 to CURR13) with up to 480mA, and general purpose LEDs (CURR2 to CURR4) with up to 160mA/LED. The general 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 blocks can be connected together (CURR 11 to CURR13 and CURR2 to CURR4). 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. In Softflash Mode the device is controlled by an I 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 - 400mA Continuous Current (@VIN = 3.2 to 5V, VOUT = 5V) - Up to 960mA Pulsed Flash Current - Programmable: 0 to 160mA, 0.625mA Resolution ! Flexible Brightness Control - Three 0 to 160mA LEDs - Individually Addressable via I2C Interface ! 2 Operating Modes -S o f t f l a s h M o d e ( I2C Interface) - 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.

AS3683

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AS3683 AMSCO

Document overview

Technical content

1 General Description

2 Key Features

3 Application

4 Block Diagram

3 C1_P

2 VBAT1

6 VBAT2

5 C2_P

7 C2_N

24 C1_N

4 CP_OUT

13 CURR11

14 CURR12

15 CURR13

19 CURR2

20 CURR3

21 CURR4

5 Application Diagrams

ams AG AS3683 overview.

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