SC654 Datasheet, PDF (1/22 Pages) Semtech Corporation – Light Management Unit for 6 LEDs with SemPulseTM Interface

SC654
POWER MANAGEMENT
Light Management Unit for
6 LEDs with SemPulseTM Interface
Features
Description
„ Input supply voltage range — 2.9V to 5.5V
„ Very high efficiency charge pump driver system with
three modes — 1x, 1.5x and 2x
„ Six programmable current sinks — 0mA to 25mA
„ Up to three LED grouping options
„ Fade-in/fade-out feature for main LED bank
„ Charge pump frequency — 250kHz
„ SemPulse single wire interface
„ Backlight current accuracy — ±1.5% typical
„ Backlight current matching — ±0.5% typical
„ LED float detection
„ Automatic sleep mode (LEDs off ) — I = 60μA (typ.)
Q
„ Shutdown current — 0.1μA (typical)
„ Ultra-thin package — 2 x 2 x 0.6 (mm)
„ Fully WEEE and RoHS compliant
Applications
„ Cellular phones, smart phones, and PDAs
„ LCD modules
„ Portable media players
„ Digital cameras
„ Personal navigation devices
„ Display/keypad backlighting and LED indicators
The SC654 is a high efficiency charge pump LED driver
using Semtech’s proprietary charge pump technology.
Performance is optimized for use in single-cell Li-ion
battery applications.
The charge pump provides backlight current utilizing six
matched current sinks. 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.
The SC654 uses the proprietary SemPulse^TM single wire
interface to control all functions of the device, including
backlight currents. The single wire interface minimizes
microcontroller and interface pin counts. The six LEDs
can be grouped in up to three separate banks that can be
independently controlled.
The SC654 enters sleep mode when all the LED drivers are
disabled. In this mode, the quiescent current is reduced
while the device continues to monitor the SemPulse
interface.
With a 2 x 2 (mm) package and four small capacitors, the
SC654 provides a complete LED driver solution with a
minimal PCB footprint.
Typical Application Circuit
V_BAT = 2.9 to 5.5V
IN
OUT
C_IN
2.2μF
SC654
BL1
From
Microprocessor
SPIF
BL2
BL3
BL4
BL5
GND
BL6
C1+ C1- C2+ C2-
C_OUT
2.2μF
C1
2.2μF
C2
2.2μF
January 30, 2009
© 2009 Semtech Corporation
US Patents: 6,504,422; 6,794,926
1