Document
10kΩ 10kΩ 2.2kΩ 2.2kΩ
07780-001
Programmable Current Backlight Driver with Ambient Light Sensor Input ADP5501
FEATURES
Efficient asynchronous boost converter for driving up to 6 white LEDs
2.7 V to 5.5 V input voltage range 128 programmable backlight LED current levels (30 mA
maximum) Programmable backlight fade-in/fade-out times Programmable backlight dim and off times Ambient light sensing with autonomous backlight
adjustment 3 auxiliary LED current sinks 64 programmable auxiliary LED current levels (14 mA
maximum) Programmable auxiliary LED fade-in/fade-out times Programmable auxiliary LED on and off times (allows
blinking) I2C-compatible serial interface Interrupt line for signaling an external processor (INT) Hard reset (RST) Current limit protection Thermal overload protection Available in small 4.0 mm × 4.0 mm, 24-lead LFCSP package
APPLICATIONS
Display backlight driver with ambient light sensor input and control and multiple LED indicator sinks
TYPICAL OPERATING CIRCUIT
2.7V TO 5.5V
1µF
I/O RAIL
4.7µH 1µF
2 1 PGND SW
21 VBAT
22 BST
23 BL_SNK CAP_OUT 20
16 VDDIO
5 SCL 4 SDA 3 INT 15 RST
ADP5501
GND 19 GND 18 GND 24
CMP_IN 17 RGB
NC NC NC NC NC NC 6 7 8 9 10 11
LED1 LED2 LED0
12
13
14
1µF
100nF VBAT
3.3V
Figure 1.
GENERAL DESCRIPTION
The ADP5501 is a versatile, single-chip, white LED backlight driver with programmable ambient light sensor input and programmable LED current. This device is designed for mediaenabled handset applications. The ADP5501 uses an I2C®compatible serial interface and a single line interrupt to communicate with the host processor.
The ADP5501 can detect ambient light levels and adjust the backlight brightness accordingly, resulting in extended battery life.
Once configured, the ADP5501 is capable of controlling the display backlight intensity, on/off timing, dimming, and fading without the intervention of the main processor, which translates into valuable battery power savings. The three auxiliary LEDs are also capable of fading and are timed on and off via register programming.
Rev. 0
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ADP5501
TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Typical Operating Circuit................................................................ 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Descriptions............................. 6 Typical Performance Characteristics ............................................. 7 Theory of Operation ........................................................................ 9 Backlight Drive Control .............................................................. 9 Backlight Operating Levels ....................................................... 10 Backlight Maximum and Dim Settings ................................... 10 Backlight Turn-On/Turn-Off/Dim .......................................... 10 Automatic Dim and Turn-Off Timers ..................................... 11 Linear Backlight Fade-In and Fade-Out.................................. 11
REVISION HISTORY
10/08—Revision 0: Initial Version
Fade Override ............................................................................. 13 Advanced Fading (Square)........................................................ 13 Advanced Fading (Cubic 1 and Cubic 2) ................................ 13 Ambient Light Sensing .............................................................. 14 Automatic Backlight Adjustment............................................. 14 LED Current Sinks ..................................................................... 15 Interrupt Output (INT) ..........................................