SC623A Datasheet, PDF (1/21 Pages) Semtech Corporation – LED Light Management Unit Charge Pump, 4 LEDs, 400mA Flash LED, and I2C 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
„ 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
SC623A
LED Light Management Unit
Charge Pump, 4 LEDs, 400mA Flash LED,
and I²C Interface
Description
The SC623A 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 SC623A uses an I²C compatible serial interface. The
interface controls all functions of the device, including
backlight and flash currents. 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.
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
VIN
VOUT
SDA ^SC623A
SCL
FLEN
EN
BL 1
BL 2
BL 3
BL 4
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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