1 Features
1• 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

2 Applications
• LED Drivers
• Constant Current Sources
• Industrial Lighting
• LED Flashlights

3 Description
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.