IN

OUT

TEMP

SW

ENABLE

TORCH

TX

SDA

SCL

GND

1 PH

10 PF

10 PF

STROBE

LED

Flash

LED

2.5 V to 5.5 V

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LM3556

SNVS796D – AUGUST 2011 – REVISED OCTOBER 2015

LM3556 1.5-A Synchronous Boost LED Flash Driver With High-Side Current Source

1 Features

3 Description

The LM3556 is a 4-MHz fixed-frequency synchronous

1

•

Grounded Cathode LED Operation for Improved

boost converter plus 1.5-A constant current driver for

Thermal Management

a high-current white LED. The high-side current

•

1.5-A High-Side Current Source for Single LED

source allows for grounded cathode LED operation

•

Accurate and Programmable LED Current from

providing flash current up to 1.5 A. An adaptive

regulation

method

ensures

the

current

source

46.9 mA to 1.5 A

remains in regulation and maximizes efficiency.

•

> 85% Efficiency in Torch Mode (at 100 mA) and

Flash Mode (at 1 A to 1.5 A)

The LM3556 is controlled via an I2C-compatible

interface. Features include: a hardware flash enable

•

Small Solution Size: < 20 mm2

(STROBE) allowing a logic input to trigger the flash

•

LED Thermal Sensing and Current Scale-Back

pulse, a hardware torch enable (TORCH) for Movie

•

Soft-Start Operation for Battery Protection

Mode or flashlight functions, a TX input which forces

the flash pulse into a low-current Torch Mode

•

Hardware Enable Pin

allowing for synchronization to RF power amplifier

•

Hardware Torch Enable

events or other high-current conditions, and an

•

Hardware Strobe Enable

integrated comparator designed to monitor an NTC

•

Synchronization Input for RF Power Amplifier

thermistor and provide an interrupt to the LED

current. With a fast 1-

μs transition from 0 mA to

Pulse Events

46.9 mA, the TORCH input pin can be used to

•

VIN Flash Monitor Optimization

develop custom LED current waveforms.

•

400-kHz I2C-Compatible Interface

The

4-MHz

switching

frequency,

overvoltage

•

I2C-Compatible Programmable NTC Trip Point

protection and adjustable current limit allow for the

•

0.4-mm Pitch, 16-Pin DSBGA Package

use of tiny, low-profile inductors and 10-µF ceramic

capacitors. The device is operates over a

−40°C to

2 Applications

+85°C temperature range.

Camera Phone LED Flash

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (MAX)

LM3556

DSBGA (16)

1.69 mm × 1.64 mm

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

the end of the data sheet.

Typical Application Circuit

1

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.