SC627 Datasheet, PDF (1/23 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, 700mA Flash LED, Dual LDOs, and SemWireTM Interface

POWER MANAGEMENT
SC627
LED Light Management Unit
Charge Pump, 4 LEDs, 700mA Flash LED,
Dual LDOs, and SemWire^TM 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
„ 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
„ 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 SC627 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 SC627 also
provides two low-dropout, low-noise linear regulators for
powering a camera module or other peripheral circuits.
The SC627 uses the proprietary SemWire^TM single wire
interface. The interface controls all functions of the
device, including backlight and flash currents as well as
two LDO voltage outputs. The single wire implementation
minimizes microcontroller and interface pin counts. The
flash/spotlight output is triggered via either the SemWire
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
SemWire
Interface
Flash
Control
C_BYP
22nF
VIN
VOUT
SWIF
FLEN ^SC627
BYP
GREF
AGND
PGND
BL1
BL2
BL3
BL4
FL
LDO1
LDO2
C_OUT
4.7μF
MAIN BACKLIGHT
FLASH
V_LDO1 = 2.5V to 3.3V
V_LDO2 = 1.5V to 1.8V
June 27, 2007
C1+ C1- C2+ C2-
C1
2.2μF
C2
2.2μF
C_LDO1
1.0μF
C_LDO2
1.0μF
© 2007 Semtech Corporation
US Patents: 6,504,422; 6,794,926
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