IN

OUT

SW

HWEN

TX

SDA

SCL

GND

1 2H

10 2F

10 2F

STROBE

LED1

Flash

LED

2.5V to 5.5V

Flash

LED

LED2

LM3643

TORCH/TEMP

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LM3643, LM3643A

SNVS967A – AUGUST 2014 – REVISED NOVEMBER 2014

LM3643 Synchronous Boost Dual LED Flash Driver with 1.5-A High-Side Current Sources

1 Features

3 Description

The LM3643 is a dual LED flash driver that provides

1

•

1.5 A Total Allowed LED Current During Operation

a high level of adjustability within a small solution

size. The LM3643 utilizes a 2-MHz or 4-MHz fixed-

•

Dual Independent LED Current Source

frequency synchronous boost converter to provide

Programmability

power to the dual 1.5-A constant current LED

sources. The total LED current the LM3643 boost can

•

Accurate and Programmable LED Current Range

from 1.4 mA to 1.5 A

current sources provide the flexibility to adjust the

•

Optimized Flash LED Current During Low Battery

current ratios between LED1 and LED2 with each

Conditions (IVFM)

driver capable of delivering a maximum of 1.5 A (ex:

•

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

Flash Mode (@1 A to 1.5 A)

1.5 A, or a current configuration with a current less

•

Grounded Cathode LED Operation for Improved

adaptive regulation method ensures the current

Thermal Management

sources

remain

in

regulation

and

maximizes

•

efficiency.

•

Hardware Strobe Enable (STROBE)

•

Synchronization Input for RF Power Amplifier

compatible

interface.

These

features

include:

Pulse Events (TX)

hardware flash and hardware torch pins (STROBE

•

Hardware Torch Enable (TORCH/TEMP)

and TORCH/TEMP), a TX interrupt, and an NTC

thermistor monitor. The device offers independently

•

Remote NTC Monitoring (TORCH/TEMP)

programmable currents in each output leg to drive the

•

LEDs in a Flash or Movie Mode (Torch) condition.

–

The 2-MHz or 4-MHz switching frequency options,

–

overvoltage protection (OVP), and adjustable current

limit allow for the use of tiny, low-profile inductors and

2 Applications

(10-µF) ceramic capacitors. The device operates over

a –40°C to 85°C ambient temperature range.

Camera Phone White LED Flash

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (MAX)

LM3643

DSBGA (12)

1.69 mm x 1.31 mm

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

the end of the datasheet.

4 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.