Features • High Voltage High-Side Current Source Allows for Grounded Cathode LED Operation • Synchronous Boost Converter • Peak Converter Efficiency >90% • Accurate and Programmable LED Current ranging from 60mA to 500mA • Adaptive LED Current Range Based on LED Configuration • Dedicated Indicator Current Source • Dedicated Torch and Strobe Pins • Dual Mode Control (General Purpose or I 2C) • Broken Inductor Detection • Output Over-Voltage Protection • Output and LED Short-Circuit Protection • 400kHz I 2C Compatible Interface • 12–Bump, 1.575 mm x 2.1 mm x 0.6 mm micro SMD Package (TLA12BCA) Description The LM3555 is a 2 MHz fixed frequency, current mode synchronous boost converter designed to drive either a single flash LED at 500 mA or two series flash LEDs at 400 mA. A high-voltage current source allows the LEDs to be terminated to the GND plane eliminating the need for an additional return trace back to the IC. A dual mode control interface allows the user to configure the LM3555 with a general purpose interface using two enable pins for control or an I 2C allowing a higher level of control. Both interfaces allow access to the indicator, assist light and flash modes. A dedicated Strobe pin provides a direct interface to trigger the flash event, while an external Torch pin provides an additional method for enabling the LEDs in a constant current mode. The LM3555 can adaptively scale the maximum flash level delivered to the LED/LEDs based upon the flash configuration, whether it be a single LED or two LEDs in series. Eight protection features are available on the LM3555 ranging from over-voltage protection, to broken inductor detection. The LM3555 has four selectable inductor current limits to help the user select an inductor that is appropriate for the design. Applications • Camera Phone LED Flash

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Datasheet

Title		Size	Date	Other Language
	LM3555 PRODUCT BRIEF Synchronous Boost Converter with 500 mA High Side LED Driver and Dual-Mode Control Interface	114 Kbytes	20-Jan-09

Featured 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

More 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
	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)
LM3555TLE	CMOS7	0	18406	0	0	1089000	4	309006723
LM3555TLX	CMOS7	0	18406	0	0	1089000	4	309006723

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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