IN

OUT

SW

TX/TORCH

SDA

SCL

1 2H

10 2F

10 2F

STROBE

LED

Flash

LED

2.5V to 5.5V

GND

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LM3642

SNVS891H – SEPTEMBER 2012 – REVISED SEPTEMBER 2015

LM3642 1.5-A Synchronous Boost LED Flash Driver With High-Side Current Source

1 Features

3 Description

The LM3642 is a 4-MHz fixed-frequency synchronous

1

•

1.5-A High-Side Current Source for Single LED

boost converter plus 1.5-A constant current driver for

•

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

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

Flash Mode (at 1 A to 1.5 A)

source allows for grounded cathode LED operation

•

Accurate Programmable Flash LED Current from

providing Flash current up to 1.5 A. An adaptive

regulation

method

ensures

the

current

source

93 mA to 1.5 A

remains in regulation and maximizes efficiency.

•

Accurate Programmable Torch LED Currents:

–

48.4 mA to 375 mA

interface. Features include a hardware flash enable

–

24 mA to 187 mA (LT option)

(STROBE) allowing a logic input to trigger the flash

•

pulse as well as a TX input which forces the flash

•

Soft-Start Operation for Battery Protection

pulse into a low-current Torch Mode, allowing for

synchronization to RF power amplifier events or other

•

Hardware Strobe Enable

high-current conditions.

•

Synchronization Input for RF Power Amplifier

The

4-MHz

switching

frequency,

overvoltage

Pulse Events

protection and adjustable current limit settings allow

•

the use of tiny, low-profile inductors and (10-µF)

•

ceramic capacitors. The device is available in a small

•

0.5-mm Pitch, 9-Bump DSBGA

9-bump DSBGA package and operates over the

−40°C to 85°C temperature range.

2 Applications

Device Information(1)

Camera Phone LED Flash

PART NUMBER

PACKAGE

BODY SIZE (MAX)

LM3642

DSBGA (9)

1.69 mm × 1.64 mm

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

the end of the data sheet.

Simplified Schematic

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.