SC624A_09 Datasheet, PDF (1/23 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, Dual LDOs,and I2C 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
„ I²C compatible interface — up to 400kHz
„ 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
SC624A
LED Light Management Unit
Charge Pump, 4 LEDs, Dual LDOs,
and I²C Interface
Description
The SC624A 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 SC624A also
provides two low-dropout, low-noise linear regulators for
powering a camera module or other peripheral circuits.
The SC624A uses an I²C compatible serial interface. The
interface controls all functions of the device, including
backlight current and two LDO voltage outputs.
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
I²C Data
I²C Clock
Enable Control
C_BYP
22nF
October 19, 2009
VIN
VOUT
SDA ^SC624A
SCL
EN
BYP
BL 1
BL 2
BL 3
BL 4
C_OUT
2.2μF
MAIN BACKLIGHT
AGND
PGND
LDO 1
LDO 2
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
© 2009 Semtech Corporation
US Patents: 6,504,422; 6,794,926
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