1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT-23 Package Evalu
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The LM3405A demo board is configured to drive a series string of high power, high brightness LEDs at a forward current of 1A using the LM3405A constant current buck regulator. The board can accept a full input operating range of 3V to 22V. The converter output voltage adjusts as needed to maintain a constant current through the LED array. The LM3405A is a step-down regulator with an output voltage range extending from a VO(MIN) of 205mV (the reference voltage) to a VO(MAX) determined by the maximum duty cycle (typically 94%). It can drive up to 5 LEDs in series at 1A forward current, with the single LED forward voltage of approximately 3.7V (Typical of white, blue, and green LEDs using InGaN technology).

  • VIN operating range of 3V to 22V
  • Drives up to 5 High-Brightness LEDs in series at 1A
  • Thin SOT23-6 package
  • 1.6MHz switching frequency
  • EN/DIM input for enabling and PWM dimming of LEDs
  • 300mΩ NMOS switch
  • 40nA shutdown current at VIN = 5V
  • Internally compensated current-mode control
  • Cycle-by-cycle current limit
  • Input voltage UVLO
  • Over-current protection
  • Thermal shutdown


  • LED Driver
  • Constant Current Source
  • Industrial Lighting
  • LED Flashlights
  • LED Lightbulbs


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1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT-23 Package


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Technical documentation
Application notes (1)
Title Type Size (KB) Date
PDF 158 01 May 2013
User guides (2)
Title Type Size (KB) Date
PDF 1582 01 May 2013
PDF 219 27 Jan 2012
More literature (1)
Title Type Size (KB) Date
PDF 38 02 Jan 2019

TI Devices (1)

Part Number Name Product Family
LM3405A  1.6-MHz, 1-A constant current buck LED driver with internal compensation  LED drivers 

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