Features Dual High Side Current Sources Grounded Cathode Allowing for Better Heat Sinking and LED Routing >90% Efficiency Ultra-Small Solution Size: < 23mm 2 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) micro SMD Description The LM3554 is a 2MHz 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 limit the output voltage during LED open circuits, and an output short circuit protection which limits the output current during shorts 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 occurred, 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. Applications Camera Phone LED Flash Controller Class D Audio Amplifier Power LED Current Source Biasing

Typical application circuit

Typical Application click for larger image Typical application circuit	Block Diagram click for larger image block diagram
Typical Performance click for larger image single toko flash efficiency vs VIN

Parameters Values Regulated LEDs 2 Total LED Current 1200 mA Boost Type Inductive Switching Frequency 2000 kHz Efficiency (peak) 95 % Input Min Voltage 2.7 Volt Input Max Voltage 5.5 Volt LED Configuration Parallel Current Matching 0.5% OutputMax Voltage 5.4 Volt Supply Current 2.7 mA Switching Type Fixed Freq Special Features Indicator, LED Temp Sense, VOUT Mode, I2C Compatible Interface, Dual TX Interrupt, VIN Monitor, Fault Detection, Programmable Current Limit PWM BrightCtrl No Analog-V BrightCtrl No Ambient Light Compensation No RGB-LED No Temperature Min -30 deg C Temperature Max 85 deg C RegType Switching Regulator PowerWise No

Datasheets

Title		Size	Date	Other Language
	LM3554 Synchronous Boost Converter with 1.2A Dual High Side LED Driver and I2C Compatible Interface C Compatible Interface	2891 Kbytes	12-Apr-11

Other Technical Documents

Title		Type	Date
	High-Performance LED Flash for Camera Phones	External Article	2009-08-10
	Things to Keep in Mind When Designing Power Management Circuitry	External Article	2009-10-20

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3554TME/NOPB RoHS Status	MICRO SMD	Full production Lead Time: 6 weeks	Distributor Region Qty AVNET-EM Worldwide 134 DIGI-KEY Worldwide 1095 FARNELL Europe and Asia 126 NEWARK Americas 126	$1.30 each at 1K+ pcs	reel of 250
LM3554TMX/NOPB RoHS Status	MICRO SMD	Full production Lead Time: 10 weeks	Distributor Region Qty CEAC Asia Pacific 30000 DIGI-KEY Worldwide 0	$1.30 each at 1K+ pcs	reel of 3000

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM3554.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM3554 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3554TMEEV/NOPB	LM3554TMEEV Evaluation Board	Full production Lead Free (RoHS)	Distributor Region Qty DIGI-KEY Worldwide 0	$150.00 each	1
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National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

Lead Free product status is available through the search tool located here

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM3554TME/NOPB	3.689	MICRO SMD	16	1	260	Detail	N/A	N/A	XYTT I SF
LM3554TMX/NOPB	3.689	MICRO SMD	16	1	260	Detail	N/A	N/A	XYTT I SF

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM3554.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM3554 is located at RoHS Status.

CAD Symbols and Models N/A

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3554TME	CMOS7	0	21301	0	0	1584000	3	449464325
LM3554TMX	CMOS7	0	21301	0	0	1584000	3	449464325

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.

For more information on Reliability Metrics, please click here.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM3554.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM3554 is located at RoHS Status.