Four White LED Backlight Driver Data Sheet ADM8843 FEATURES GENERAL DESCRIPTION Drives 4 LEDs from a 2.6 V to 5.5 V (Li-Ion) input supply The ADM8843 uses charge pump technology to provide the 1/1.5/2 fractional charge pump to maximize power to drive up to four LEDs. The LEDs are used for back- power efficiency lighting a color LCD display that has regulated constant current 0.3% typical LED current matching for uniform brightness intensity. The main display can use up to Up to 88% power efficiency over Li-Ion range three LEDs, and the sub display uses one LED. The CTRL1 and Powers main and sub display LEDs with individual shutdown CTRL2 digital input control pins control the shutdown opera- 2 Package footprint only 9 mm (3 mm 3 mm) tion and the brightness of the main and sub displays. Package height only 0.75 mm To maximize power efficiency, the charge pump can operate in Low power shutdown mode 1, 1.5, or 2 mode. The charge pump automatically switches Shutdown function among 1/1.5/2 modes, based on the input voltage, to Soft start limiting in-rush current maintain sufficient drive for the LED anodes at the highest APPLICATIONS power efficiency. Cellular phones with main and sub displays Improved brightness matching of the LEDs is achieved by a White LED backlighting feedback pin that senses individual LED current with a typical Camera flash/strobes and movie light applications matching accuracy of 0.3%. Micro TFT color displays DSC PDAs FUNCTIONAL BLOCK DIAGRAM C1 C2 1F 1F V ADM8843 CC V OUT CHARGE PUMP C3 C4 1/1.5/2 MODE 2.2F MAIN SUB 4.7F OSC CTRL1 CONTROL LOGIC CTRL2 V REF FB1 FB2 FB3 FB4 LED I SET CURRENT CONTROL R SET CIRCUIT CURRENT CONTROLLED SINKS GND Figure 1. Rev. E Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20042018 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Technical Support www.analog.com CURRENT CONTROL 1 CURRENT CONTROL 2 CURRENT CONTROL 3 CURRENT CONTROL 4 05050-001ADM8843 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 LED Brightness Control Using a PWM Signal Applied to VPWM ............................................................................................. 12 Applications ....................................................................................... 1 LED Brightness Control Using a DC Voltage Applied to General Description ......................................................................... 1 V .......................................................................................... 12 BRIGHT Functional Block Diagram .............................................................. 1 Applications ..................................................................................... 13 Revision History ............................................................................... 2 Layout Considerations and Noise ............................................ 13 Specifications ..................................................................................... 3 White LED Shorting .................................................................. 13 Absolute Maximum Ratings ............................................................ 4 Driving Four LEDs in the Main Display Only ....................... 13 Thermal Resistance ...................................................................... 4 Driving Fewer than Four LEDs ................................................ 13 ESD Caution .................................................................................. 4 Using Smaller Capacitor Values ............................................... 14 Pin Configuration and Function Descriptions ............................. 5 Power Efficiency ......................................................................... 15 Typical Performance Characteristics ............................................. 6 Outline Dimensions ....................................................................... 16 Theory of Operation ........................................................................ 9 Ordering Guide .......................................................................... 16 Automatic Gain Control ............................................................ 10 Brightness Control with a Digital PWM Signal ..................... 10 REVISION HISTORY 7/2018Rev. D to Rev. E 4/2010Rev. A to Rev. B Change to Features Section ............................................................. 1 Removed CP-16-12 Package ............................................. Universal Changed Thermal Characteristics Section to Thermal Change to Figure 2 ............................................................................ 5 Resistance Section ............................................................................ 4 Change to Figure 6 ............................................................................ 6 Changes to Thermal Resistance Section ........................................ 4 Changes to Figure 14 ......................................................................... 7 Added Table 3 Renumbered Sequentially .................................... 4 Changes to Figure 15 ......................................................................... 8 Updated Outline Dimensions ....................................................... 16 Updated Outline Dimensions ....................................................... 16 Changes to Ordering Guide .......................................................... 16 Changes to Ordering Guide .......................................................... 16 3/2017Rev. C to Rev. D 12/2006Rev. 0 to Rev. A Changed CP-16-3 to CP-16-22 .................................... Throughout Change to Thermal Characteristics Section .................................. 4 Changes to Figure 2 .......................................................................... 5 Changes to Outline Dimensions .................................................. 16 Updated Outline Dimensions ....................................................... 16 Changes to Ordering Guide .......................................................... 16 Changes to Ordering Guide .......................................................... 16 10/2004Revision 0: Initial Version 1/2011Rev. B to Rev. C Changes to Figure 14 ........................................................................ 7 Rev. E Page 2 of 16