Features • Dual High Side Current Sources • Grounded Cathode Allowing for Better Heatsinking and LED Routing • >90% Efficiency • Ultra-Small Solution Size: < 23mm2 • Four Operating Modes: Torch, Flash, LED Indicator and Voltage Output • Accurate and Programmable LED Current from 37.5mA to 1.2A • Programmable 4.5V or 5.0V Constant Output Voltage • Hardware Flash and Torch Enable • LED Thermal Sensing and Current Scaleback • Software Selectable Input Voltage Monitor • Programmable Flash Timeout • Dual Synchronization Inputs for RF Power Amplifier Pulse Events • Open and Short LED Detection • Active High Hardware Enable for Protection Against System Faults • 400kHz I 2C Compatible Interface • 16-Bump (1.7mm × 1.7mm × 0.6mm) µSMD Description The LM3554 is a 2 MHz fixed frequency, current mode synchronous boost converter. The device is designed to operate as a dual 600mA (1.2A total) constant current driver for high current white LEDs, or as a regulated 4.5V or 5V voltage source. The dual high side current sources allow for grounded cathode LED operation. An adaptive regulation method ensures the current source for each LED remains in regulation and maximizes efficiency. The main features include: an I 2C compatible interface for controlling the LED current or the desired output voltage, a hardware Flash enable input for direct triggering of the Flash pulse, and dual TX inputs which force the Flash pulse into a low current Torch mode allowing for synchronization to RF power amplifier events or other high current conditions. Additionally, an active high hardware enable (HWEN) input provides a hardware shutdown during system software failures. Five protection features are available within the LM3554 including a software selectable input voltage monitor, an internal comparator, for interfacing with an external temperature sensor, four selectable current limits to ensure the battery current is kept below a predetermined peak level, an over-voltage protection feature to keeps the output voltage below the OVP threshold in case of an open LED, and an output short circuit protection which limits the output current during an output short to GND. Additionally, the device provides various fault indicators including: a thermal fault flag indicating the LED temperature has tripped the thermal threshold, a flag indicating a TX event has occured, a flag indicating the flash timeout counter has expired, a flag indicating the devices die temperature has reached the thermal shutdown threshold, and a flag indicating an open or short LED. Notice: This document is not a full datasheet. For more imformation regarding this product, or to order samples, please contact your National Semiconductor sales office or visit http://www.national.com/support/dir.html. Applications • Camera Phone LED Flash Controller • Class D Audio Amplifier Power • LED Current Source Biasing

Typical application circuit MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application click for larger image Typical application circuit

Datasheet

Title		Size	Date	Other Language
	LM3554 PRODUCT BRIEF Synchronous Boost Converter with 1.2A Dual High Side LED Drivers and I 2 C Compatible Interface	148 Kbytes	8-Jun-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)
LM3554TME	CMOS7	0	18406	0	0	1089000	4	309006723
LM3554TMX	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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