Product details

Input voltage (type) DC/DC Topology Boost, Current Mode Vin (Min) (V) 2.7 Vin (Max) (V) 5.5 Iout (Max) (A) 1.5 Iq (Typ) (mA) 1 Features I2C Control, Input/Output Isolation, LED Thermal Monitor, Load Disconnect During Shutdown, 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) 2.7 Vin (Max) (V) 5.5 Iout (Max) (A) 1.5 Iq (Typ) (mA) 1 Features I2C Control, Input/Output Isolation, LED Thermal Monitor, Load Disconnect During Shutdown, OVP, Over Current Protection, Synchronous Rectification Operating temperature range (C) -40 to 85 Dimming method Analog, PWM
DSBGA (YFQ) 20 0 mm² 1.65 x 2.05
  • High-Side Current Sources Allowing for Grounded
    LED Cathode for Improved Thermal Management
  • > 85% Efficiency in Torch and Flash Modes
  • Small Solution Size < 20 mm2
  • Accurate and Programmable Flash LED Current from
    24 mA to 1.5 A in 11.7-mA Steps
  • Accurate and Programmable Torch LED Current
    from 2.5 mA to 187 mA in 1.5-mA Steps
  • Dual 1.5-A High-Side Current Sources for Dual
    LED Drive
  • Hardware Flash and Torch Enables
  • Hardware Enable Pin
  • Soft-Start Operation for Battery Protection
  • LED Thermal Sensing and Current Scale-Back
  • Synchronization Input for RF Power Amplifier
    Pulse Events
  • VIN Flash Monitor Optimization
  • 1-MHz I²C-Compatible Interface
  • I²C-Programmable NTC Trip Point
  • 0.4-mm Pitch, 20-Bump DSBGA
  • High-Side Current Sources Allowing for Grounded
    LED Cathode for Improved Thermal Management
  • > 85% Efficiency in Torch and Flash Modes
  • Small Solution Size < 20 mm2
  • Accurate and Programmable Flash LED Current from
    24 mA to 1.5 A in 11.7-mA Steps
  • Accurate and Programmable Torch LED Current
    from 2.5 mA to 187 mA in 1.5-mA Steps
  • Dual 1.5-A High-Side Current Sources for Dual
    LED Drive
  • Hardware Flash and Torch Enables
  • Hardware Enable Pin
  • Soft-Start Operation for Battery Protection
  • LED Thermal Sensing and Current Scale-Back
  • Synchronization Input for RF Power Amplifier
    Pulse Events
  • VIN Flash Monitor Optimization
  • 1-MHz I²C-Compatible Interface
  • I²C-Programmable NTC Trip Point
  • 0.4-mm Pitch, 20-Bump DSBGA

The LM3646 utilizes a 4-MHz fixed-frequency synchronous boost converter to provide power to dual 1.5-A constant current LED sources. The high-side current sources allow for grounded cathode LED operation providing flash current up to 1.5 A total. An adaptive headroom regulation scheme ensures the LED currents remain in regulation and maximizes efficiency. The combination of dual LED driving capability, high LED current, small solution size and high level of adjustability make the LM3646 perfect for camera phone LED flash and torch applications.

The LM3646 is controlled through an I2C-compatible interface. The main features of the LM3646 include: a hardware flash enable (STROBE) input for direct triggering of the flash pulse, a hardware Torch enable (TORCH) for movie mode or flashlight functions, a TX input which forces the flash pulse into a low-current torch mode allowing for synchronization to RF power amplifier events or other high-current conditions, an integrated comparator designed to monitor an NTC thermistor and provide an interrupt to the LED current, and a programmable input voltage monitor which monitors the battery voltage and can reduce the flash current during low battery conditions. A hardware enable (ENABLE) input provides a hardware shutdown during system software failures.

The 4-MHz switching frequency, overvoltage protection, and adjustable current limit allow for the use of tiny, low-profile inductors and (10-µF) ceramic capacitors. The device is available in a small 20-bump DSBGA package and operates over the –40°C to 85°C temperature range.

The LM3646 utilizes a 4-MHz fixed-frequency synchronous boost converter to provide power to dual 1.5-A constant current LED sources. The high-side current sources allow for grounded cathode LED operation providing flash current up to 1.5 A total. An adaptive headroom regulation scheme ensures the LED currents remain in regulation and maximizes efficiency. The combination of dual LED driving capability, high LED current, small solution size and high level of adjustability make the LM3646 perfect for camera phone LED flash and torch applications.

The LM3646 is controlled through an I2C-compatible interface. The main features of the LM3646 include: a hardware flash enable (STROBE) input for direct triggering of the flash pulse, a hardware Torch enable (TORCH) for movie mode or flashlight functions, a TX input which forces the flash pulse into a low-current torch mode allowing for synchronization to RF power amplifier events or other high-current conditions, an integrated comparator designed to monitor an NTC thermistor and provide an interrupt to the LED current, and a programmable input voltage monitor which monitors the battery voltage and can reduce the flash current during low battery conditions. A hardware enable (ENABLE) input provides a hardware shutdown during system software failures.

The 4-MHz switching frequency, overvoltage protection, and adjustable current limit allow for the use of tiny, low-profile inductors and (10-µF) ceramic capacitors. The device is available in a small 20-bump DSBGA package and operates over the –40°C to 85°C temperature range.

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Technical documentation

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Type Title Date
* Data sheet LM3646 1.5-A Synchronous Boost Converter With Dual High-Side Current Sources and I2C-Compatible Interface datasheet (Rev. A) 28 Nov 2014
White paper Common LED Functions and LED Driver Design Considerations 21 Sep 2020
Application note LED Flash-Protection Features 23 Aug 2017
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 Take better selfies with innovative LED flashes 18 Nov 2014
Technical article Solving the automotive EMI issues in new cars with all the screens 11 Sep 2014
EVM User's guide LM3646EVM User’s Guide (Rev. A) 01 Jul 2014

Design & development

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

Evaluation board

LM3646EVM — Evaluation Module for LM3646 Dual LED Flash Driver with I2C Compatible Interface

The LM3646EVM evaluation module helps designers evaluate the operation and performance of the LM3646 1.5A Synchronous Boost Dual LED driver. The EVM offers configurability via I2C-compatible interface. It can be enabled in Flash or Torch mode via the I2C interface or externally using the Strobe and (...)

Driver or library

LM3646SW-LINUX — Linux Driver for LM3646

The Linux driver supports the LM3646 LED Flash Driver. The Linux driver supports communication through the I2C bus and interfaces with the V4L2 sub-system.

 

Linux Mainline Status

Available in Linux Main line: Yes
Available through git.ti.com: N/A

Supported Devices:

  • lm3646

 

Linux Source Files

The files (...)

Simulation model

LM3646 PSpice Transient Model

SNVMA23.ZIP (79 KB) - PSpice Model
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 (YFQ) 20 View options

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