HWEN

SCL

SDA

STROBE

TX1/TORCH/

GPIO1

IN

OUT

GND

LED1

LED2

LEDI/NTC

SW

4.5-V or 5-V DC Power Rail

Flash

LEDs

Indicator

LED

ENVM/TX2

/GPIO

VBIAS

D1

D2

0.1 µF

4.7 µF

4.7 µF

2.2 µH

2

NŸ

Thermistor

2.5 V

± 5.5 V

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM3554

SNVS549C – JUNE 2009 – REVISED FEBRUARY 2016

Compatible Interface

1

1 Features

1

•

Input Voltage: 2.5 V to 5.5 V

•

Programmable 4.5-V or 5-V Constant Output

Voltage

•

Dual High-Side Current Sources

•

Grounded Cathode Allowing for Better Heat

Sinking and LED Routing

•

> 90% Efficiency

•

•

Four Operating Modes: Torch, Flash, LED

Indicator, and Voltage Output

•

Accurate and Programmable LED Current from

37.5 mA to 1.2 A

•

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

•

2 Applications

•

Camera Phone LED Flash Controller

•

Class D Audio Amplifier Power

•

LED Current Source Biasing

3 Description

The LM3554 is a 2-MHz fixed-frequency, current-

mode synchronous boost converter. The device is

designed to operate as a dual 600-mA (1.2 A total)

constant-current driver for high-current white LEDs, or

as a regulated 4.5-V or 5-V voltage source.

The

main

features

include:

an

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 overvoltage 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.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (MAX)

LM3554

DSBGA (16)

1.685 mm × 1.685

mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Typical Application Circuit