SC623 Datasheet, PDF (1/21 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, 400mA Flash LED, and SemWireTM 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
„ Flash LED — 400mA max in flash mode, 250mA max
continuous for spotlight
„ 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
SC623
LED Light Management Unit
Charge Pump, 4 LEDs, 400mA Flash LED,
and SemWire^TM Interface
Description
The SC623 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 SC623 uses the proprietary SemWire^TM single wire
interface. The interface controls all functions of the device,
including backlight and flash currents. 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.
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 ^SC623
BL1
BL2
BL3
BL4
GREF
FL
AGND
PGND
C1+ C1- C2+ C2-
C1
2.2μF
C2
2.2μF
C_OUT
4.7μF
June 27, 2007
© 2007 Semtech Corporation
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US Patents: 6,504,422; 6,794,926
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