SC662 Datasheet, PDF (1/30 Pages) Semtech Corporation – Backlight Driver for 6 LEDs with SemPulse® Interface

POWER MANAGEMENT
Features
 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
 Selectable charge pump frequency — 250kHz/1MHz
 SemPulse^® single wire interface
 Backlight current accuracy — ±1.5% typical
 Backlight current matching — ±0.5% typical
 LED float detection
 Automatic sleep mode with all LEDs off
 Sleep mode quiescent current — 60µA typical
 Shutdown current — 0.1µA typical
 Ultra-thin package — 2 x 2 x 0.6 (mm)
 Lead-free and halogen-free
 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
SC662
Backlight Driver for 6 LEDs
with SemPulse® Interface
Description
The SC662 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 SC662 uses the proprietary SemPulse 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 charge pump switches at 1MHz or 250kHz, and the
frequency is selectable using the SemPulse interface. Both
1MHz and 250kHz frequencies are supported by 0402 size
(1005 metric) ceramic capacitors.
The SC662 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.
Typical Application Circuit
CIN
1.0µF
From
Microprocessor
IN
OUT
SC662
SPIF
BL1
BL2
BL3
BL4
BL5
GND
BL6
COUT
1.0µF
C1+ C1- C2+ C2-
C1
1.0µF
C2
1.0µF
November 30, 2010
© 2010 Semtech Corporation