SC614 Datasheet, PDF (1/25 Pages) Semtech Corporation – Low Noise Backlight and Flash Driver With Serial Interface

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Description
The SC614 is a high efficiency charge pump LED driver
using Semtech’s proprietary mAhXLife^TM technology.
Performance is optimized for use in Li-ion battery
applications.
Each of 7 LED currents can be programmed via the
I²C serial control bus. M1 through M4 are for LED
backlighting of LCD main displays. S1/FL3 through
S3/FL1 can be used for backlighting sub displays and/
or for driving flash LEDs. These three current sinks are
configurable over the I²C interface for any combination
of pins for sub or flash use.
The charge pump automatically selects an operating
mode based on the number of active loads, input
voltage, and load currents required. Any combination of
LED drivers can be enabled at one time, allowing the
SC614 to power any combination of backlight and flash
required by the application.
Two dedicated pins, MDIM and SDIM, are provided to
allow PWM dimming of the main and sub-backlights and
one dedicated pin, FL, allows direct control of the flash.
All three pins can be utilized without having to use the
I²C interface once the registers are set up.
The enable pin can be used to put the device in
low-current shutdown mode drawing 0.1μA (typ), or a reg-
ister can be written that sets the device in a sleep mode
that reduces the current to 50μA (typ).
Typical Application Circuit
SC614
Low Noise Backlight and Flash
Driver With Serial Interface
Features
‹ Four independent current sinks for main backlight,
adjustable from 0.4mA to 32mA each
‹ Dedicated MDIM pin for PWM dimming of main
backlight
‹ Three independent current sinks for sub-backlight
or flash, adjustable from 0.4mA to 102mA each
‹ Configurable sub-backlight or flash sinks
‹ Dedicated SDIM pin for PWM dimming of sub-
backlight
‹ Dedicated FL pin for flash control
‹ Current accuracy to within ±1.5% down to 4.8mA
‹ Current matching to within ±0.5% down to 4.8mA
‹ Very high efficiency over 90% of battery life
‹ Shutdown current 0.1μA (typ)
‹ Three charge pump operating modes: 1x, 1.5x,
and 2x
‹ I²C serial interface
‹ Soft-start/in-rush current limiting
‹ 1.33MHz and 250kHz programmable fixed
frequency options
‹ Short-circuit/thermal protection
‹ Output open circuit protection
‹ MLPQ-24 package (4mm x 4mm), fully WEEE and
RoHS compliant
Applications
‹ Cellular phone backlighting and flash
‹ LCD modules
‹ PDA backlighting and flash
‹ RGB LED Driver
VLOGIC
R1
Pull-up
R2
Pull-up
EN
SDIM
MDIM
VBAT
U1
11 _VIN
C1
17 _VIN
2u2
2 _EN
3 _SDIM
4
MDIM
SDA
SCL
FL
Note: R1 and R2
pull-up resistors are a
requirement of the I2C
s pecif ic ation
7
SDA
8
SCL
6
FL
5 _ASEL
12 _GND
21
GND
SC614
VOUT ⁹
328mA Max Continuous
434mA Max (500ms)
VOUT ¹⁶
C2
1u
M1 ¹
M2 ²⁴
23
M3
22
M4
S1/FL3 ²⁰
19
S2/FL2
18
S3/FL1
32mA Max
32mA Max
32mA Max
32mA Max
306mA Max.
MAIN BACKLIGHT
D1
D2
D3
D4
LED
LED
LED
LED
FLASH
D5
LED
C3 1u
C4 1u
April 28, 2006
1
United States Patent No. 6,504,422
www.semtech.com