SC622_09 Datasheet, PDF (1/21 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 400mA Flash LED, Dual LDOs, and SemWire Interface

POWER MANAGEMENT
Features
„ Input supply voltage range — 3.0V to 5.5V
„ Charge pump modes — 1x, 1.5x and 2x
„ Flash LED — 400mA max in flash mode, 250mA max
continuous for spotlight
„ Two programmable 200mA low-noise LDO regulators
„ Charge pump frequency — 250kHz
„ SemWire^TM single wire interface — up to 75kbit/s
„ 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
„ Lead-free and halogen-free
„ WEEE and RoHS compliant
Applications
„ Cellular phone flash
„ PDA flash
„ Camera I/O and core power
SC622
LED Light Management Unit
Charge Pump, 400mA Flash LED, Dual
LDOs, and SemWire^TM Interface
Description
The SC622 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 continuous or bursted current
to a flash LED using a dedicated flash driver current sink.
The load and supply conditions determine whether the
charge pump operates in 1x, 1.5x, or 2x mode. A flash-
timeout feature disables the flash if active for longer than
1 second. The SC622 also provides two low-dropout, low-
noise linear regulators for powering a camera module or
other peripheral circuits.
The SC622 uses the proprietary SemWire^TM single wire
interface. The interface controls all functions of the device,
including flash current and 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
VIN
VOUT
SWIF
FLEN ^SC622
C_OUT
4.7μF
FLASH
October 20, 2009
C_BYP
22nF
BYP
GREF
AGND
PGND
FL
LDO1
LDO2
V_LDO1 = 2.5V to 3.3V
V_LDO2 = 1.5V to 1.8V
C1+ C1- C2+ C2-
C1
2.2μF
C2
2.2μF
C_LDO1
1.0μF
C_LDO2
1.0μF
© 2009 Semtech Corporation
US Patents: 6,504,422; 6,794,926
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