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

LM3644

TORCH/TEMP

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LM3644, LM3644TT

SNVSA52D – AUGUST 2014 – REVISED SEPTEMBER 2015

LM3644 Dual 1.5-A Current Source Camera Flash LED Driver

1 Features

3 Description

The LM3644 is a dual LED flash driver that provides

1

•

Dual Independent 1.5-A LED Current Source

a high level of adjustability within a small solution

Programmability

size. The LM3644 utilizes a 2-MHz or 4-MHz fixed-

•

Accurate and Programmable LED Current Range

frequency synchronous boost converter to provide

from 1.4 mA to 1.5 A

power to the dual 1.5-A constant current LED

sources. The dual 128 level current sources provide

•

Torch Currents up to 360 mA (LM3644TT)

the flexibility to adjust the current ratios between

•

Flash Timeout Values up to 1.6 seconds

LED1 and LED2. An adaptive regulation method

(LM3644TT)

ensures the current sources remain in regulation and

•

Optimized Flash LED Current During Low Battery

maximizes efficiency.

Conditions (IVFM)

•

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

compatible

interface.

These

features

include:

Flash Mode (at 1 A to 1.5 A)

hardware flash and hardware torch pins (STROBE

•

Grounded Cathode LED Operation for Improved

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

thermistor monitor. The device offers independently

Thermal Management

programmable currents in each output leg to drive the

•

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

•

Hardware Strobe Enable (STROBE)

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

•

Synchronization Input for RF Power Amplifier

overvoltage protection (OVP), and adjustable current

Pulse Events (TX)

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

•

Hardware Torch Enable (TORCH/TEMP)

10-µF ceramic capacitors. The device operates over

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

•

Remote NTC Monitoring (TORCH/TEMP)

•

Device Information(1)

–

PART NUMBER

PACKAGE

BODY SIZE (MAX)

LM3644

DSBGA (12)

1.69 mm x 1.31 mm

2 Applications

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

Camera Phone White LED Flash

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.