SC624_09 Datasheet, PDF (1/22 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, Dual LDOs,and SemWireTM Interface

POWER MANAGEMENT
Features
„ Input supply voltage range — 3.0V to 5.5V
„ Charge pump modes — 1x, 1.5x and 2x
„ Four programmable current sinks with 32 steps from
0.5mA to 25mA
„ Two programmable 200mA low-noise LDO regulators
„ Charge pump frequency — 250kHz
„ SemWire^TM single wire interface — up to 75kbit/s
„ Backlight current accuracy ±1.5% typical
„ Backlight current matching ±0.5% typical
„ Programmable fade-in/fade-out for main backlight
„ Automatic sleep mode (LEDs off ) — I = 100μA
Q
„ Low shutdown current — 0.1μA (typical)
„ Ultra-thin package — 3mm x 3mm x 0.6mm
„ Lead-free and halogen-free
„ WEEE and RoHS compliant
Applications
„ Cellular phone backlighting
„ PDA backlighting
„ Camera I/O and core power
SC624
LED Light Management Unit
Charge Pump, 4 LEDs, Dual LDOs,
and SemWire^TM Interface
Description
The SC624 is a high efficiency charge pump LED driver
using Semtech’s proprietary mAhXLife^TM technology.
Performance is optimized for use in single-cell Li-ion
battery applications.
The charge pump provides backlight current in
conjunction with four matched current sinks. The load
and supply conditions determine whether the charge
pump operates in 1x, 1.5x, or 2x mode. An optional fading
feature that gradually adjusts the backlight current is
provided to simplify control software. The SC624 also
provides two low-dropout, low-noise linear regulators for
powering a camera module or other peripheral circuits.
The SC624 uses the proprietary SemWire^TM single wire
interface. The interface controls all functions of the device,
including backlight current and two LDO voltage outputs.
The single wire implementation minimizes microcontroller
and interface pin counts.
In sleep mode, the device reduces quiescent current to
100μA while continuing to monitor the serial interface.
The two LDOs can be enabled when the device is in sleep
mode. Total current reduces to 0.1μA in shutdown.
Typical Application Circuit
V_BAT
C_IN
1μF
SemWire
Interface
C_BYP
22nF
October 20, 2009
VIN
VOUT
SWIF
SC624
C_OUT
2.2μF
MAIN BACKLIGHT
BYP
GREF
AGND
PGND
BL1
BL2
BL3
BL4
LDO1
LDO2
V_LDO1 = 2.5V to 3.3V
V_LDO2 = 1.5V to 1.8V
C1+ C1- C2+ C2-
C1
C2
1μF
1μF
C_LDO1
1μF
C_LDO2
1μF
US Patents: 6,504,422; 6,794,926
© 2009 Semtech Corporation
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