SC653 Datasheet, PDF (1/22 Pages) Semtech Corporation – Light Management Unit with 2 LDOs and SemPulse®Interface

POWER MANAGEMENT
Features
„ Input supply voltage range — 2.9V to 5.5V
„ Four programmable current sinks with 29 steps from
0mA to 25mA
„ Very high efficiency charge pump driver system with
three modes — 1x, 1.5x and 2x
„ Two programmable 200mA low-noise LDO regulators
„ Charge pump frequency — 250kHz
„ SemPulse single wire interface
„ Backlight current accuracy — ±1.5% typical
„ Backlight current matching — ±0.5% typical
„ Fade-in/fade-out feature for main backlight
„ Automatic sleep mode (LEDs off ) — I = 100μA
Q
„ Shutdown current — 0.1μA (typical)
„ Ultra-thin package — 2.3 x 2.3 x 0.6 (mm)
„ Lead-free and halogen-free
„ WEEE and RoHS compliant
Applications
„ Cellular phones, smart phones, and PDAs
„ LCD modules
„ Portable media players
„ Digital cameras and GPS units
„ Display backlighting and LED indicators
SC653
Light Management Unit with
2 LDOs and SemPulse® Interface
Description
The SC653 is a highly integrated light management unit
that provides two low-noise LDOs, a multi-mode high
efficiency charge pump, and four programmable LED
drivers. Performance is optimized for use in single-cell Li-
ion battery applications.
The load and supply conditions determine whether the
charge pump operates in 1x, 1.5x, or 2x mode. A program-
mable fading feature can be enabled to gradually adjust
the backlight current, simplifying control software. The
low-dropout, low-noise linear regulators can be used for
powering a camera module or other peripheral circuits.
The SC653 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 SC653 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. The two LDOs can be enabled when the device is in
sleep mode.
Typical Application Circuit
V_BAT = 2.9V to 5.5V
C_IN
2.2μF
SemPulse
Interface
GND2
GND2
C_BYP
22nF
SC653
IN
OUT
SPIF
C_OUT
2.2μF
MAIN BACKLIGHT
ENL1
ENL2
BYP
BL1
GND2
BL2
BL3
BL4
GND1
GND2
LDO1
LDO2
V_LDO1 = 1.5V to 3.3V
V_LDO2 = 1.2V to 1.8V
GND1
C1+ C1-
GND2
C1
2.2μF
C2+ C2-
C_LDO1
1μF
C_LDO2
1μF
C2 ^GND1
2.2μF
GND1
US Patents: 6,504,422; 6,794,926
October 21, 2009
© 2009 Semtech Corporation
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