SC627A Datasheet, PDF (1/24 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, 700mA Flash LED, Dual LDOs, and I2C Interface

POWER MANAGEMENT
SC627A
LED Light Management Unit
Charge Pump, 4 LEDs, 700mA Flash LED,
Dual LDOs, and I²C Interface
Features
Description
„ 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
„ Flash LED — 700mA max in flash mode, 250mA max
continuous for spotlight
„ Two user-configurable 100mA 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
„ External flash control pin to sync with camera
„ Optional 1s flash time out
„ Automatic sleep mode (LEDs off ) — I = 100μA
Q
„ Low shutdown current — 0.1μA (typical)
„ Ultra-thin package — 3mm x 3mm x 0.6mm
„ Fully WEEE and RoHS compliant
Applications
„ Cellular phone backlighting and flash
„ PDA backlighting and flash
„ Camera I/O and core power
The SC627A 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. It also can
supply continuous or bursted current to a flash LED using
the dedicated flash driver current sink. 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. A flash-timeout feature disables
the flash if active for longer than 1 second.The SC627A also
provides two low-dropout, low-noise linear regulators for
powering a camera module or other peripheral circuits.
The SC627A uses an I²C compatible serial interface. The
interface controls all functions of the device, including
backlight and flash currents as well as two LDO voltage
outputs. The flash/spotlight output is triggered via either
the I²C interface or a dedicated pin.
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
2.2μF
I²C Data
I²C Clock
Flash Control
Enable Control
C_BYP
22nF
VIN
VOUT
SDA ^SC627A
SCL
FLEN
EN
BYP
BL 1
BL 2
BL 3
BL 4
FL
AGND
PGND
LDO 1
LDO 2
C_OUT
4.7μF
MAIN BACKLIGHT
FLASH
V_LDO1 = 2.5V to 3.3V
V_LDO2 = 1.5V to 1.8V
May 21, 2007
C1+ C1- C2+ C2-
C1
2.2μF
C2
2.2μF
C_LDO1
1μF
C_LDO2
1μF
© 2007 Semtech Corporation
US Patents: 6,504,422; 6,794,926
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