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a u s t ri a m i c r o s y s t e m s
AS3683 1A Backlight and Camera LED Power Charge Pump
P ro du c t B ri e f
1 General Description
The AS3683 is a low-noise, high-current 1A charge pump designed for camera flash LEDs and LCD backlighting 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 (CURR11 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 funlight or a movie indicator lamp. To meet high-flash current requirements (up to 960mA), both current source blocks can be connected together (CURR11 to CURR13 and CURR2 to CURR4). The AS3683 utilizes austriamicrosystems's patent-pending 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 architectures. In Softflash Mode the device is controlled by an I2C 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
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High-Power 1A Charge Pump - 1:1, 1:1.5, and 1:2 Intelligent Adaptive Mode Setting (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 - Softflash Mode (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 (6A), Interface Fully Operating Low Shut-Down Current (0.2A) 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
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3 Application
Lighting management for cameras, mobile telephones, PDAs, and other 1-cell Li+ or 3-cell NiMH powered devices.
(c) 1997-2005, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved. www.austriamicrosystems.com Revision 1.0
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4 Block Diagram
Figure 1. AS3683 Block Diagram
V2_5
22
AS3683
Digital Supply
2 6 5
VBAT1 VBAT2 C2_P C2_N C1_P C1_N CP_OUT
RBIAS
23
Bandgap and Current Reference
Charge Pump 1:1, 1:1.5, 1:2
7 3 24 4
ADR
1
VDD_GPIO
12
CLK/P2 DATA/P1
8 9
Digital Part Serial Interface
Mode Selector
Current Source
STROBE/F2 11
13 14
CURR11 CURR12 CURR13
GPIO0/P0
10
15
SFL/F1
16
Current Source
T1/F0 17
19
CURR2
20 HFL 18 21
CURR3 CURR4 GND Exposed Pad
(c) 1997-2005, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved. www.austriamicrosystems.com Revision 1.0
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5 Application Diagrams
Figure 2. Softflash Mode Application Diagram
Battery V2_5 1F C3 RBIAS 23 5 240k R1 7 V2.5 = 41h GND = 40h ADR 1 3 VDD_GPIO 12 24 4 C1_P C1_N 1F C5 C2_P C2_N 1F C4 22 2 6 VBAT1 VBAT2 2.2F C1
Feature Interface Current Sinks Total Current Flash LEDs Addressable Strobe Trigger Strobe Preview General Purpose LEDs (CURR2, CURR3, CURR4) Current Sinks Current per Sink Addressable
Softflash Mode I2C 3 to 6 0 to 960mA Block Pin STROBE/F2 or software Pin GPIO0/P0 or software 3 0 to 160mA Individually
R4
1 - 10k DATA/P1
9
AS3683
CP_OUT Flash & Preview Camera 2.2F Flash LED C6
CLK/P2
8
13
CURR11
STROBE/F2
11
14 CURR12 15 19 CURR13 CURR2
GPIO0/P0
10
SFL/F1
16
Note: Connect all 6 current sinks in parallel or use general purpose current sink for other functions (e.g., indicatorlamp).
T1/F0 HFL
17 18
20 21
CURR3 CURR4 Battery or CP_OUT
GND
Exposed Pad
Figure 3. Hardflash Mode Application Diagram
Battery V2_5 1F C3 22 2 6 5 7 VDD_GPIO Selectable DATA/P1 MSB Preview CLK/P2 8 9 24 4 C1_N 12 3 VBAT1 VBAT2 2.2F C2_P C2_N C1_P 1F C5 1F C4 C1
Feature Interface Current Sinks Total Current Flash LEDs Addressable Strobe Trigger
Hardflash Mode Dedicated Control Pins for Strobe (3x) & Preview (3x) 6 Strobe: 0 to 900mA Preview: 0 to 480mA Block By Strobe Control Pins
RBIAS ADR
23 1
240k
R1
CP_OUT Flash & Preview Camera 2.2F Flash LED C6
AS3683
13 14 15
Strobe Preview By Preview Control Pins General Purpose LEDs (CURR2, CURR3, CURR4) Current Sinks Current per Sink Addressable N/A N/A N/A
Preview Control (Active-Low)
GPIO0/P0 LSB Preview STROBE/F2 MSB Flash SFL/F1
10
CURR11 CURR12 CURR13 CURR2 CURR3 CURR4
11
16 19
Strobe Control (Active-Low)
T1/F0 LSB Flash Battery HFL
17 20 21
18
GND
Exposed Pad
(c) 1997-2005, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved. www.austriamicrosystems.com Revision 1.0
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Copyrights
Copyright (c) 1997-2005, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered (R). All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters austriamicrosystems AG A-8141 Schloss Premstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 e-mail: info@austriamicrosystems.com For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com
austriamicrosystems
- a leap ahead in analog
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(c) 1997-2005, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved. www.austriamicrosystems.com Revision 1.0

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