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SC643 Datasheet, PDF (1/26 Pages) Semtech Corporation – Light Management Unit with 4 LDOs and SemPulse®Interface | |||
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SC643
Light Management Unit with
4 LDOs and SemPulse® Interface
POWER MANAGEMENT
Features
Description
 Input supply voltage range â 2.9V to 5.5V
 Very high efficiency charge pump driver system with
three modes â 1x, 1.5x, and 2x
 Five programmable current sinks with 29 increments
from 0mA to 25mA
 Four programmable 200mA low-noise LDO regulators
 Programmable driver configurations for main and
sub-display backlight
 Fade-in/fade-out feature for main and sub display
backlight
 SemPulse single wire interface
 Backlight current accuracy â ±1.5% typical
 Backlight current matching â ±0.5% typical
 External enable pin for optional control of LDO4
 Automatic sleep mode with LEDs off
 Shutdown current â 0.1μA typical
 Ultra-thin package â 3 x 3 x 0.6 (mm)
 Lead free and Halogen free
 WEEE and RoHS compliant
Applications
 Cellular phones, smart phones, and PDAs
 LCD display modules
 Portable media players
 Digital cameras and GPS units
 Display backlighting and LED indicators
The SC643 is a high efficiency charge pump LED driver
using Semtechâs proprietary charge pump technology.
Performance is optimized for use in single cell Li-ion
battery applications.
Display backlighting is provided through five matched
current sinks with integrated fade-in and fade-out con-
trols. The LEDs can be driven as a single set or as two
different sets (for main and sub displays) with indepen-
dent controls. Four low noise, low dropout (LDO) regulators
are provided to supply power for camera module I/O and
other peripheral circuits. An external enable pin is also
provided for one LDO for added flexibility.
The SC643 uses the proprietary SemPulse® single wire
interface. This interface controls all functions of the device,
including backlight currents and LDO voltage outputs.
The single wire interface minimizes microcontroller and
interface pin counts.
The SC643 enters sleep mode when all the LED drivers are
disabled. In this mode, the quiescent current is reduced
while the device continues to monitor the SemPulse inter-
face. Any combination of LDOs may be enabled when in
sleep mode.
Typical Application Circuit
VBAT = 2.9V to 5.5V
4.7μF
SemPulse
Interface
Motor
Control
22nF
SC643
IN
OUT
SPIF
ENL4
BYP
AGND
PGND
BL1
BL2
BL3
BL4
BL5
LDO1
LDO2
LDO3
LDO4
4.7μF
Main Backlight
Sub
Backlight
VLDO1 = 1.5V to 3.3V
VLDO2 = 1.2V to 1.8V
VLDO3 = 1.5V to 3.3V
1.0μF 1.0μF 1.0μF 1.0μF Motor
October 8, 2009
2.2μF
2.2μF
© 2009 Semtech Corporation
US Patents: 6,504,422; 6,794,926
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