SC668 8 LED Light Management Unit Automatic Dropout Prevention , Ambient Light Sense Input, PWM Dimming, and 4 LDOs POWER MANAGEMENT Features Description Eight LED backlight sinks with 32 current settings The SC668 is a highly integrated light management unit from 0mA to 25mA that provides programmable current for up to eight LED Up to four LED backlight banks current sinks. Four LED banks are provided to allow set- Lighting effects fade-in/fade-out, breathe, blink, tings for various LED zones or indicators. Four low-noise auto-dim full, and auto-dim partial functions LDOs with programmable outputs ranging from 1.2V to 3.3V ADP (Automatic Dropout Protection) for backlights and 200mA maximum output current are also included. ALS (Ambient Light Sense) option sets the backlight ADP limits the maximum LED current to a level that ensures brightness according to ambient lighting conditions 2 the LEDs maintain matched currents when the supply I C Bus fast mode and standard mode voltage approaches dropout. This feature produces accept- Backlight current accuracy 1.5% typical able light output at low supply voltage levels without Backlight current matching 0.5% typical requiring a boost converter or charge pump. Four programmable 200mA low-noise LDO regulators PWM interface (200Hz to 50kHz) with internal digital 2 Two interfaces are provided for design flexibility. The I C low-pass lfi ter interface controls the LED on/off functions, assigns the Automatic sleep mode with all LEDs off LEDs to backlight banks, programs the LED currents, pro- Shutdown current 0.1A typical grams the lighting eeff cts, enables the LDOs, and sets the Ultra-thin package 3 x 3 x 0.6 (mm) LDO output voltages. The PWM interface reduces the Lead-free and halogen-free current setting for LED bank 1 by a factor equal to the duty WEEE and RoHS compliant cycle of the applied PWM signal. A lfi ter at the PWM input Applications converts the pulsed signal to a DC current level, resulting in less switching noise compared to pulsed current methods. Cellular phones, smart phones, and PDAs LCD modules The ADI input translates the voltage from an external ALS Portable media players and digital cameras (Ambient Light Sensor) into a digitized code using a sigma- Personal navigation devices delta ADC. This block includes level detection to adjust the Display/keypad backlighting and LED indicators current setting of bank 1 with two dieff rent programmable levels based on the ambient light level. An interrupt output transitions low to notify the host processor that a level adjustment has been made. Typical Application Circuit VIN V IN SC668 2.9 to 5.5V IN BL1 BL2 C IN GND BL3 BL4 2 I C Data SDA BL5 2 BL6 I C Clock SCL BL7 Backlight PWM PWM BL8 Device Enable EN LDO1 LDO1 V LDO4 ADI LDO2 LDO2 LDO3 LDO3 BYP LDO4 LDO4 C BYP C C1 C2 C3 4 Ambient Light Sensor December 2, 2010 2010 Semtech Corporation 1SC668 Pin Configuration Ordering Information Device Package (1)(2) SC668ULTRT MLPQ-UT-20 33 SC668EVB Evaluation Board 20 19 18 17 16 Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. LDO1 1 15 PWM (2) Lead-free package only. Device is WEEE and RoHS compliant and halogen-free. TOP VIEW VIN 2 14 SDA 3 GND 13 SCL BL8 4 12 ADI T BL1 BL7 5 11 6 7 8 9 10 MLPQ-UT-20 3x3, 20 LEAD = 35C/W JA Marking Information 668 yyww xxxx yyww = Date Code xxxx = Semtech Lot Number 2 BL6 LDO2 BL5 LDO3 BL4 LDO4 BL3 BYP BL2 EN