SC627A
LED Light Management Unit
Charge Pump, 4 LEDs, 700mA Flash LED,
Dual LDOs, and I2C Interface
POWER MANAGEMENT
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
The SC627A is a high efficiency charge pump LED driver
using Semtech’s proprietary mAhXLifeTM technology.
Performance is optimized for use in single-cell Li-ion
battery applications.
Flash LED — 700mA max in flash mode, 250mA max
continuous for spotlight
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.
Two programmable 200mA low-noise LDO regulators
Charge pump frequency — 250kHz
I2C compatible interface — up to 400kHz
Backlight current accuracy 1.5ꢀ typical
Backlight current matching 0.5ꢀ 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) — IQ = 100μA
Low shutdown current — 0.1μA (typical)
Ultra-thin package — 3mm x 3mm x 0.6mm
Lead-free and halogen-free
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.
WEEE and RoHS compliant
Applications
Cellular phone backlighting and flash
PDA backlighting and flash
Camera I/O and core power
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
MAIN BACKLIGHT
FLASH
VIN
VOUT
VBAT
COUT
4.7μF
I2C Data
I2C Clock
SC627A
SDA
SCL
FLEN
EN
CIN
2.2μF
Flash Control
BL
BL
BL
BL
1
2
3
4
Enable Control
BYP
FL
CBYP
VLDO1 = 2.5V to 3.3V
LDO2 = 1.5V to 1.8V
LDO
LDO
1
2
AGND
PGND
22nF
V
C1+ C1- C2+ C2-
CLDO1
1μF
CLDO2
1μF
C2
2.2μF
C1
2.2μF
US Patents: 6,504,422; 6,794,926
1
October 19, 2009
© 2009 Semtech Corporation