LM3551_14 Datasheet, PDF (1/23 Pages) Texas Instruments – 1A White LED Driver with Flash Timeout Protection

LM3551, LM3552
www.ti.com
SNVS371C – AUGUST 2005 – REVISED MARCH 2011
LM3551 /LM3552 1A White LED Driver with Flash Timeout Protection
Check for Samples: LM3551, LM3552
FEATURES
1
•2 Up to 1A Total Drive Current
• Flash Timeout Protection
• Independent Torch/Flash/Shutdown Modes
• LED Disconnect in Shutdown
• Programmable Soft-Start Limits Inrush Current
• Over-Voltage Protection
• Wide Voltage Range 2.7 to 5.5V
• 1.25MHz Constant Switching Frequency
• Small, Low Profile Package, Non-Pullback
WSON(4mm x 4mm)
APPLICATIONS
• White LED Camera Flash
• White LED Torch (Flashlight)
• DSC (Digital Still Camera) Flash
• Cellular Camera Phone Flash
• PDA Camera Flash
• Camcorder Torch (Flashlight) Lamp
DESCRIPTION
The LM3551 and LM3552 are fixed frequency, current mode step-up DC/DC converters with two integrated
NFETs that can be used for precision LED brightness control. The devices are capable of driving loads up to 1A
from a single-cell Li-Ion battery.
The LM3551 and LM3552 can drive one or more high current flash LEDs either in a high power Flash mode or a
lower power Torch mode using the TORCH/FLASH pin. A programmable Timeout function on the FTO pin forces
the internal NFETs to turn off after a certain user defined time. An external SD pin (LM3551) or EN pin (LM3552)
is available to put the device into low power shutdown mode. During shutdown, the feedback resistors and the
load are disconnected from the input to avoid leakage current paths to ground.
User programmable soft-start circuitry has been integrated to eliminate large inrush currents at start-up. Over-
voltage protection circuitry and a 1.25MHz switching frequency allow for the use of small, low-cost output
capacitors with lower voltage ratings. The LM3551 and LM3552 are available in a low profile 14-pin WSON
package.
Typical Application Circuits
VBAT
VBAT
L1
D1
Sharp
GM5BW05340A
Flash LED
SW OVP
CIN
VIN
FB
VC
RC ^FTO
CC ^CFTO
LM3551/2
GND
L1
SD/ T/F
EN
D1
RT
RF
FET-T
FET-F
SS
CSS
LUMILED
LXCL-PWF1
Flash LED
COUT
VIN
CIN
VC
RC ^FTO
CC ^CFTO
SW OVP
FB
LM3551/2
SD/ T/F
EN
RT
FET-T
FET-F
SS
CSS
COUT
RF
1
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2005–2011, Texas Instruments Incorporated