Features • 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 LLP14 (4mm x 4mm) 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 LLP package. 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

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Typical Application click for larger image	Block Diagram click for larger image
Typical Performance click for larger image

Datasheet

Title		Size	Date	Other Language
	LM3551/LM3552 1A White LED Driver with Flash Timeout Protection	756 Kbytes	28-Feb-06

Featured Application Notes

Title		Size	Date	Other Language
	AN-1495: Application Note 1495 LM3552 White LED Flash Driver Evaluation Board	626 Kbytes	27-Sep-06	中文

More Application Notes

Title		Size	Date	Other Language
	AN-1780: Application Note 1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface	1427 Kbytes	12-Mar-08

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3552SD	ABCD150	0	34175	0	0	4234000	1	1201409060
LM3552SDX	ABCD150	0	34175	0	0	4234000	1	1201409060

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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