1.6MHz 1A Constant Current Buck Regulator for Powering LEDs

1.6MHz 1A Constant Current Buck Regulator for Powering LEDs - LM3405

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The LM3405 is a 1-A constant current buck LED driver designed to provide a simple, high efficiency solution for driving high power LEDs. With a 0.205-V reference voltage feedback control to minimize power dissipation, an external resistor sets the current as required for driving various types of LEDs. Switching frequency is internally set to 1.6 MHz, allowing small surface mount inductors and capacitors to be used. The LM3405 uses current-mode control and internal compensation offering ease of use and predictable, high performance regulation over a wide range of operating conditions. With a maximum input voltage of 15 V, the device can drive up to 3 High-Brightness LEDs in series at 1-A forward current, with the single LED forward voltage of approximately 3.7 V. Additional features include user accessible EN/DIM pin for enabling and PWM dimming of LEDs, thermal shutdown, cycle-by-cycle current limit and overcurrent protection.


  • VIN Operating Range of 3 V to 15 V
  • Drives up to 5 High-Brightness LEDs in Series at 1 A
  • Thin SOT-6 Package
  • 1.6-MHz Switching Frequency
  • EN/DIM Input for Enabling and PWM Dimming of LEDs
  • 300-mΩ NMOS Switch
  • 40-nA Shutdown Current at VIN = 5 V
  • Internally Compensated Current-mode Control
  • Cycle-by-Cycle Current Limit
  • Input Voltage UVLO
  • Overcurrent Protection
  • Thermal Shutdown

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Parametrics Compare all products in Illumination & General Lighting LED Driver

Input Voltage (Type)
Vin (Min) (V)
Vin (Max) (V)
Iout (Max) (A)
Vout (Min) (V)
Vout (Max) (V)
Regulated Outputs (#)
Dimming Method
Power Factor Correction (Min)
Switching Frequency (Min) (kHz)
Switching Frequency (Max) (kHz)
Iq (Typ) (mA)
Vref (V)
UVLO Thresholds On/Off (V)
Operating Temperature Range (C)
LM3405 LM3405A
DC/DC    DC/DC   
3    3   
15    22   
1    1   
0.2    0.2   
13.5    20   
1    1   
Buck    Buck   
PWM    PWM   
N/A    N/A   
1600    1600   
1600    1600   
1.8    1.8   
0.205    0.205   
2.74 / 2.3    2.74 / 2.3   
Integrated Switch
Thermal Shutdown   
Integrated Switch
Thermal Shutdown   
-40 to 125    -40 to 125   
6SOT-23-THIN    6SOT-23-THIN