Charge-Pump, Parallel Backlight Driver with Image Content PWM Input Data Sheet ADP8870 FEATURES APPLICATIONS Charge pump with automatic gain selection of 1, 1.5, and Mobile display backlighting 2 for maximum efficiency Mobile phone keypad backlighting Two high accuracy (5%) phototransistor inputs for RGB LED lighting automated ambient light sensing (ALS) LED indication 5 programmable ambient light-sensing zones for optimal General backlighting of small format displays backlight power savings TYPICAL OPERATING CIRCUIT Independent ALS control of D7, for automated response of V DD ALS keypad lighting to ambient light levels OPTIONAL PHOTOSENSOR PWM input can be used for content adaptive brightness V OUT PHOTO- control (CABC) of any, or all, of the LEDs SENSOR PWM input scales the LED output current 0.1F 7 independent, programmable LED drivers 6 drivers capable of 30 mA (maximum) 0.1F D1 D2 D3 D4 D5 D6 D7 CMP IN 1 driver capable of 60 mA (maximum) Programmable maximum current limit (128 levels) V IN 1F Standby mode for <1 A current consumption V OUT 16 programmable fade-in and fade-out times (0.1 sec to 5.5 sec) 1F VDDIO with choice of square or cubic rates Fading override C1+ 2 I C-compatible interface for all programming C1 nRST ADP8870 1F Dedicated reset pin and built-in power-on reset (POR) C1 SDA Short-circuit, overvoltage, and overtemperature protection C2+ Internal soft start to limit inrush currents SCL C2 1F Input-to-output isolation during faults or shutdown C2 nINT Operates down to V = 2.5 V, with undervoltage lockout IN PWM GND (UVLO) at 2.0 V. Available in a small, 2.15 mm 2.36 mm 0.6 mm wafer level chip scale package (WLCSP) or a 4 mm 4 mm 0.75 mm Figure 1. lead frame chip scale package (LFCSP) GENERAL DESCRIPTION The ADP8870 combines a programmable backlight LED 60 mA (maximum). All LEDs are individually programmable for charge-pump driver with automatic phototransistor control of minimum/maximum current and fade-in/fade-out times through 2 the brightness (LED current) and a PWM input to control the an I C interface. These LEDs can also be combined into groups scale of the output current. This combination allows significant to reduce the processor instructions during fade-in and fade-out. power savings because it automatically changes the current Driving these components is a two-capacitor charge pump intensity based on the sensed ambient lighting levels and the with gains of 1, 1.5, and 2. This setup is capable of driving a display image content. It performs this function automatically, maximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. A full eliminating the need for a processor to monitor the photo- suite of safety features, including short-circuit, overvoltage, and transistor. The light intensity thresholds are fully programmable overtemperature protection, allows easy implementation of a 2 via the I C interface. safe and robust design. Additionally, input inrush currents are The ADP8870 allows up to six LEDs to be independently driven up limited via an integrated soft start combined with controlled input-to-output isolation. to 30 mA (maximum). An additional seventh LED can be driven to Rev. C 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 20122017 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. 08829-001ADP8870 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 D7 Ambient Light-Sensing Control......................................... 20 Applications ....................................................................................... 1 Automatic Backlight Adjustment ............................................. 20 Typical Operating Circuit ................................................................ 1 Independent Sink Control (ISC) .............................................. 21 General Description ......................................................................... 1 Short-Circuit Protection (SCP) Mode ..................................... 21 Revision History ............................................................................... 2 Overvoltage Protection (OVP) ................................................. 21 Specifications ..................................................................................... 3 Thermal Shutdown (TSD)/ Overtemperature Protection .... 21 Absolute Maximum Ratings ............................................................ 6 Interrupts ..................................................................................... 23 Maximum Temperature Ranges ................................................. 6 Backlight Off Interrupt .............................................................. 23 Thermal Resistance ...................................................................... 6 Applications Information .............................................................. 24 ESD Caution .................................................................................. 6 Layout Guidelines....................................................................... 24 Pin Configurations and Function Descriptions ........................... 7 Example Circuit .......................................................................... 25 2 Typical Performance Characteristics ............................................. 8 I C Programming and Digital Control ........................................ 26 Theory of Operation ...................................................................... 12 Register Summary .......................................................................... 28 Power Stage.................................................................................. 13 Register Details ............................................................................... 29 Operating Modes ........................................................................ 14 Manufacturer and Device ID (MFDVID)Register 0x00 ... 29 Image Content Control .............................................................. 15 Mode Control Register (MDCR)Register 0x01.................. 29 Backlight Operating Levels ....................................................... 16 Interrupt Status Register (INT STAT)Register 0x02 ........ 30 Backlight Maximum and Dim Settings ................................... 16 Interrupt Enable (INT EN)Register 0x03 .......................... 30 Automated Fade-In and Fade-Out ........................................... 17 Backlight Register Descriptions ............................................... 31 Backlight Turn On/Turn Off/Dim ........................................... 17 Independent Sink Register Descriptions ................................. 40 Automatic Dim and Turn Off Timers...................................... 18 Comparator Register Descriptions .......................................... 50 Fade Override ............................................................................. 18 Outline Dimensions ....................................................................... 56 Backlight Ambient Light Sensing ............................................. 19 Ordering Guide .......................................................................... 57 REVISION HISTORY 10/2017Rev. B to Rev. C Changed CP-20-10 to CP-20-8 .................................... Throughout Updated Outline Dimensions ....................................................... 57 Changes to Ordering Guide .......................................................... 57 1/2014Rev. A to Rev. B Change to Figure 35 ....................................................................... 17 8/2012Revision A: Initial Version Rev. C Page 2 of 57