Product details

Input voltage (type) DC/DC Topology Boost, Current Mode Vin (Min) (V) 2.5 Vin (Max) (V) 5.5 Iout (Max) (A) 2.5 Iq (Typ) (mA) 0.3 Features I2C Control, IR Mode, LED Thermal Monitor, OVP, Over Current Protection, Synchronous Rectification Operating temperature range (C) -40 to 85 Dimming method Analog, PWM
Input voltage (type) DC/DC Topology Boost, Current Mode Vin (Min) (V) 2.5 Vin (Max) (V) 5.5 Iout (Max) (A) 2.5 Iq (Typ) (mA) 0.3 Features I2C Control, IR Mode, LED Thermal Monitor, OVP, Over Current Protection, Synchronous Rectification Operating temperature range (C) -40 to 85 Dimming method Analog, PWM
DSBGA (YFF) 12 2 mm² 1.32 x 1.7
  • Dual Independent 1.5-A LED Current Source Programmability
  • Accurate and Programmable LED Current Range from 1.4 mA to 1.5 A
  • Torch Currents up to 360 mA (LM3644TT)
  • Flash Timeout Values up to 1.6 seconds (LM3644TT)
  • Optimized Flash LED Current During Low Battery Conditions (IVFM)
  • > 85% Efficiency in Torch Mode (at 100 mA) and Flash Mode (at 1 A to 1.5 A)
  • Grounded Cathode LED Operation for Improved Thermal Management
  • Small Solution Size: < 16 mm2
  • Hardware Strobe Enable (STROBE)
  • Synchronization Input for RF Power Amplifier Pulse Events (TX)
  • Hardware Torch Enable (TORCH/TEMP)
  • Remote NTC Monitoring (TORCH/TEMP)
  • 400-kHz I2C-Compatible Interface
    • LM3644 (I2C Address = 0x63)
  • Dual Independent 1.5-A LED Current Source Programmability
  • Accurate and Programmable LED Current Range from 1.4 mA to 1.5 A
  • Torch Currents up to 360 mA (LM3644TT)
  • Flash Timeout Values up to 1.6 seconds (LM3644TT)
  • Optimized Flash LED Current During Low Battery Conditions (IVFM)
  • > 85% Efficiency in Torch Mode (at 100 mA) and Flash Mode (at 1 A to 1.5 A)
  • Grounded Cathode LED Operation for Improved Thermal Management
  • Small Solution Size: < 16 mm2
  • Hardware Strobe Enable (STROBE)
  • Synchronization Input for RF Power Amplifier Pulse Events (TX)
  • Hardware Torch Enable (TORCH/TEMP)
  • Remote NTC Monitoring (TORCH/TEMP)
  • 400-kHz I2C-Compatible Interface
    • LM3644 (I2C Address = 0x63)

The LM3644 is a dual LED flash driver that provides a high level of adjustability within a small solution size. The LM3644 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the dual 1.5-A constant current LED sources. The dual 128 level current sources provide the flexibility to adjust the current ratios between LED1 and LED2. An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.

Features of the LM3644 are controlled via an I2C-compatible interface. These features include: hardware flash and hardware torch pins (STROBE and TORCH/TEMP), a TX interrupt, and an NTC thermistor monitor. The device offers independently 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 10-µF ceramic capacitors. The device operates over a –40°C to +85°C ambient temperature range.

For all available packages, see the orderable addendum at the end of the data sheet.

The LM3644 is a dual LED flash driver that provides a high level of adjustability within a small solution size. The LM3644 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the dual 1.5-A constant current LED sources. The dual 128 level current sources provide the flexibility to adjust the current ratios between LED1 and LED2. An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.

Features of the LM3644 are controlled via an I2C-compatible interface. These features include: hardware flash and hardware torch pins (STROBE and TORCH/TEMP), a TX interrupt, and an NTC thermistor monitor. The device offers independently 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 10-µF ceramic capacitors. The device operates over a –40°C to +85°C ambient temperature range.

For all available packages, see the orderable addendum at the end of the data sheet.

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Technical documentation

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Type Title Date
* Data sheet LM3644 Dual 1.5-A Current Source Camera Flash LED Driver datasheet (Rev. E) 08 Sep 2016
White paper Common LED Functions and LED Driver Design Considerations 21 Sep 2020
Application note LED Flash-Protection Features 23 Aug 2017
Application note Using Flash LED Drivers for Infrared (IR) LED Applications 20 Mar 2017
Application note Using the LM3643/4/8 in an Inductorless and/or Simplified PCB Routing Configurat 11 Oct 2016
Technical article Here's how body electronics and lighting technology are changing the driving experience 26 Sep 2016
Technical article LED brightness adjustment: high-frequency PWM dimming 26 Aug 2016
Technical article Shrink your LED flash solution 10 Dec 2015
Technical article Take better selfies with innovative LED flashes 18 Nov 2014
User guide LM3644 User Guide 28 May 2014

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

LM3644EVM — Synchronous Boost Dual LED Flash Driver Evaluation Module W/ 1.5A High-Side Current Sources

The LM3644EVM aids in evaluation of the LM3643 Synchronous Boost Dual LED Flash Driver W/ 1.5A High-Side Current Sources.  The 2/4 MHz synchronous boost provides power to the dual independently controllable high side current sources.  Each current source can provide a current up to 1.5A (...)

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GUI for evaluation module (EVM)

LM3644EVM

SNVC175.ZIP (2164 KB)
Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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DSBGA (YFF) 12 View options

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