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LM3645

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Synchronous boost quad LED flash driver with 2A high-side current sources

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Data sheet

LM3645

ACTIVE
Data sheet Order now

Product details

Input voltage type DC/DC Topology Boost, Current Source Vin (min) (V) 2.5 Vin (max) (V) 5.5 Vout (max) (V) 5.5 Vout (min) (V) 2.5 Features I2C control, IR Mode, LED Thermal Monitor, Over Current Protection, Over Voltage Protection, Synchronous Rectification Operating temperature range (°C) -40 to 85 Dimming method Analog Number of channels 4 Rating Catalog
Input voltage type DC/DC Topology Boost, Current Source Vin (min) (V) 2.5 Vin (max) (V) 5.5 Vout (max) (V) 5.5 Vout (min) (V) 2.5 Features I2C control, IR Mode, LED Thermal Monitor, Over Current Protection, Over Voltage Protection, Synchronous Rectification Operating temperature range (°C) -40 to 85 Dimming method Analog Number of channels 4 Rating Catalog
DSBGA (YCG) 25 3.0625 mm² 1.75 x 1.75
  • Quad independent led current source programmability
  • Accurate and programmable LED current range from 0.525 mA to 2 A
  • Optimized flash LED current during low battery conditions (IVFM)
  • > 85% efficiency in torch mode (at 100 mA) and flash mode (at 1 A to 2 A)
  • Grounded cathode LED operation for improved thermal management
  • Dual hardware strobe enable (STR1, STR2)
  • Synchronization input for RF power amplifier pulse events (TORCH/TX)
  • Hardware torch enable (TORCH/Tx)
  • Dual remote NTC monitoring (TEMP1, TEMP2)
  • Fixed output voltage mode
  • 1-MHz I2C-compatible interface
    • (I2C Address = 0x65)
  • Quad independent led current source programmability
  • Accurate and programmable LED current range from 0.525 mA to 2 A
  • Optimized flash LED current during low battery conditions (IVFM)
  • > 85% efficiency in torch mode (at 100 mA) and flash mode (at 1 A to 2 A)
  • Grounded cathode LED operation for improved thermal management
  • Dual hardware strobe enable (STR1, STR2)
  • Synchronization input for RF power amplifier pulse events (TORCH/TX)
  • Hardware torch enable (TORCH/Tx)
  • Dual remote NTC monitoring (TEMP1, TEMP2)
  • Fixed output voltage mode
  • 1-MHz I2C-compatible interface
    • (I2C Address = 0x65)

The LM3645 is a quad LED flash driver that provides a high level of adjustability within a small solution size. The LM3645 utilizes a synchronous boost converter to provide power to the quad 2A constant current LED sources. The quad 256 level current sources provide the flexibility to adjust the current ratios between LED1, LED2, LED3 and LED4 with each driver capable of delivering a maximum of 2A. An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.

Features of the LM3645 are controlled via an I2C-compatible interface. These features include: dual hardware flash pins and a hardware torch or Tx interrupt pin (STR1, STR2 and TORCH/TX), and dual NTC thermistor monitors. The device offers independently programmable currents in each output leg to drive the LEDs in a flash or movie mode (Torch) condition as well as a fast turn-on and turn-off IR Mode.

Two switching frequency options, overvoltage protection (OVP), and adjustable current limit allow for the use of tiny, low-profile inductors and 10µF ceramic capacitors. The device operates over a –40°C to +85°C ambient temperature range.

The LM3645 is a quad LED flash driver that provides a high level of adjustability within a small solution size. The LM3645 utilizes a synchronous boost converter to provide power to the quad 2A constant current LED sources. The quad 256 level current sources provide the flexibility to adjust the current ratios between LED1, LED2, LED3 and LED4 with each driver capable of delivering a maximum of 2A. An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.

Features of the LM3645 are controlled via an I2C-compatible interface. These features include: dual hardware flash pins and a hardware torch or Tx interrupt pin (STR1, STR2 and TORCH/TX), and dual NTC thermistor monitors. The device offers independently programmable currents in each output leg to drive the LEDs in a flash or movie mode (Torch) condition as well as a fast turn-on and turn-off IR Mode.

Two switching frequency options, overvoltage protection (OVP), and adjustable current limit allow for the use of tiny, low-profile inductors and 10µF ceramic capacitors. The device operates over a –40°C to +85°C ambient temperature range.
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* Data sheet LM3645 Synchronous Boost Quad LED Flash Driver with 2-A High-Side Current Sources datasheet PDF | HTML 26 Sep 2024

Design & development

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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 (...)

User guide: PDF
Not available on TI.com
Evaluation board

LM3645EVM — LM3645 evaluation module

The LM3645 evaluation module (EVM) helps designers evaluate the operation and performance of the LM3645 high-current LED driver. The device offers configurability via I2C-compatible interface. It can be enabled in flash or torch mode. The module utilizes four LEDs mounted on the EVM.
User guide: PDF | HTML
Not available on TI.com
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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