POWER MANAGEMENT
1
SC628A
LED Flash Driver
Charge Pump with 1000mA Flash Mode,
275mA Spotlight Mode, and I
2
C Interface
Features
Input supply voltage range — 3.0V to 5.5V
Charge pump modes — 1x, 1.5x and 2x
Flash LED — 1000mA max in ash mode, 275mA max
continuous for spotlight
Charge pump frequency — 250kHz
I
2
C compatible interface — up to 400kHz
External ash control pin to sync with camera
One second ash time out with disable feature
Automatic sleep mode ( ash o ) — I
Q
= 100μA
Low shutdown current — 0.1μA (typical)
Ultra-thin package — 3mm x 3mm x 0.6mm
Fully WEEE and RoHS compliant
Applications
Cellular phone ash
PDA ash
Description
The SC628A is a high e ciency charge pump LED driver
using Semtech’s proprietary charge pump technology.
Performance is optimized for use in single-cell Li-ion
battery applications. The load and supply conditions
determine whether the charge pump operates in 1x, 1.5x,
or 2x mode.
The charge pump provides continuous spotlight mode
current or pulsed ash mode current to an LED using a
dedicated current sink. In ash mode, a ash-timeout
feature turns o the ash if active for longer than 1 second.
In spotlight mode, the timeout feature is disabled to allow
continuous operation of the LED.
The SC628A uses an I
2
C compatible serial interface to set
the ash mode or the spotlight mode current. The ash/
spotlight output is triggered via either the I
2
C interface or
a dedicated ash enable pin (FLEN).
In sleep mode, the device reduces quiescent current to
100μA while continuing to monitor the serial interface.
Total current reduces to 0.1
μA in shutdown.
SC628A
IN
SDA
FLEN
AGND
PGND
OUT
FL
C
IN
4.7μF
1C+ C1- C2+ C2-
I
2
C Data
Flash Control
Enable Control
I
2
C Clock
SCL
EN
V
BAT
= 3.0V to 5.5V
C1
2.2μF
C2
2.2μF
C
OUT
4.7μF
FLASH
US Patents: 6,504,422; 6,794,926
Typical Application Circuit
July 14, 2009