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.