SC635 Datasheet, PDF (1/12 Pages) Semtech Corporation – Charge Pump Flash LED Driver

POWER MANAGEMENT
Description
Features
SC635
Charge Pump
Flash LED Driver
The SC635 is a high-current charge pump designed spe-
cifically for use with white LEDs used in camera flash ap-
plications. Only two small bucket capacitors are required
to develop the output drive, providing a low EMI solution
compared to inductive boost regulators.
The SC635 has two modes of operation: Flash mode and
Spotlight mode. In Flash mode, the SC635 is capable of
delivering 200mA to a high-intensity LED during image
capture.In Spotlight mode the SC635 outputs 40% of the
Flash mode current for general purpose lighting or status
indication.
u Two selectable modes - Flash and Spotlight
u 200mA max output - Flash Mode
u Spotlight mode set to 40% of Flash Current
u 3.0V to 5.25V Input Range
u External pins for control of flash and spotlight modes
for synchronization to a camera module or graphics
controller
u Short circuit, over-voltage, and over-temperature
protection
u Soft-start functionality
u Micro Lead Package MLPD-10, 3mm x 3mm
An external resistor is connected in series with the LED to
set the current. In Flash mode, this resistor can dissipate
up to 50mW, reducing the power dissipation requirement
of the SC635. The flash input (FLASH) overrides the con-
trol input (CTRL) to make sure the flash function is acti-
vated when called for.
The thermally efficient MLPD-10 package and ceramic by-
pass and bucket capacitors make the SC635 a high out-
put current driver that requires minimal PCB area.
Applications
u Mobile Camera Phones
u Digital Cameras
u PDAs with Built-in Cameras
Typical Application Circuit
Typical Application Circuit
VBAT
10µF
1µF
1µF
FLASH
CTRL
1 _VIN ^SC635 _VOUT 9
8 _C1+
GND ³
1µF
4 _C1-
ISET ⁶
10 _C2+
CTRL ⁷
2
C2-
5
FLASH
white LED
RSET
December 2, 2005
www.semtech.com