SC667 Datasheet, PDF (1/47 Pages) Semtech Corporation – 7 LED Light Management Unit Automatic Dropout Prevention, Ambient Light Sense Input, PWM Dimming, and 4 LDOs

POWER MANAGEMENT
SC667
7 LED Light Management Unit
Automatic Dropout Prevention, Ambient Light
Sense Input, PWM Dimming, and 4 LDOs
Features
Description
 Seven LED backlight sinks with 32 current settings
The SC667 is a highly integrated light management unit
from 0mA to 25mA
that provides programmable current for up to seven 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 Prevention) for backlights
and 200mA maximum output current are also included.
 ALS (Ambient Light Sense) option sets the backlight
brightness according to ambient lighting conditions
 I²C Bus fast mode and standard mode
 IRQ (Interrupt request) — open-drain output indi-
cates a change of state for the ALS
 Backlight current accuracy — ±1.5% typical
ADP limits the maximum LED current to a level that ensures
the LEDs maintain matched currents when the supply
voltage approaches dropout. This feature produces accept-
able light output at low supply voltage levels without
requiring a boost converter or charge pump.
 Backlight current matching — ±0.5% typical
 Four programmable 200mA low-noise LDO regulators
 PWM interface (200Hz to 50kHz) with internal digital
low-pass filter
 Automatic sleep mode with all LEDs off
 Shutdown current — 0.1µA typical
 Ultra-thin package — 3 x 3 x 0.6 (mm)
 Lead-free and halogen-free
 WEEE and RoHS compliant
Applications
Two interfaces are provided for design flexibility. The I²C
interface controls the LED on/off functions, assigns the
LEDs to backlight banks, programs the LED currents, pro-
grams the lighting effects, enables the LDOs, and sets the
LDO output voltages. The PWM interface reduces the
current setting for LED bank #1 by a factor equal to the duty
cycle of the applied PWM signal. A filter at the PWM input
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
 Portable media players and digital cameras
 Personal navigation devices
 Display/keypad backlighting and LED indicators
The ADI input translates the voltage from an external ALS
(Ambient Light Sensor) into a digitized code using a sigma-
delta ADC. This block includes level detection to adjust the
current setting of bank #1 with two different 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
2.9 to 5.5V
I²C Data
I²C Clock
Backlight PWM
Device Enable
VLDO4
RSDA
VIN
CIN
RSCL
IN ^SC667 BL1
BL2
GND
BL3
BL4
SDA
BL5
SCL
BL6
BL7
PWM
IRQ
EN
LDO1
ADI
LDO2
LDO3
BYP
LDO4
VIN
VDD
R1
Flag for ALS
LDO1
LDO2
LDO3
LDO4
CBYP
C1
C2
C3
C4
Ambient Light Sensor
May 21, 2010
© 2010 Semtech Corporation