HONG KONG: National Semiconductor Corp. has added two new light-emitting diode (LED) drivers to its PowerWise energy-efficient product family. National's LM3401 and LM3405A LED drivers power 1W to 5W, high-brightness LEDs found in industrial and automotive applications as well as general illumination applications such as solid state and signage.  Each offers a wide input voltage range and provides a constant current to regulate the LED brightness and low feedback voltage to minimize power dissipation.

Featuring a voltage range from 4.5V to 35V, National's high-efficient LM3401 LED driver includes a scalable current drive of greater than 3A and a 100 percent duty cycle.  A low feedback voltage of 0.2V and accuracy within 3 percent provides a constant current to provide constant color output from an LED.

The LM3405A LED driver features a voltage range from 3V to 22V and is able to regulate from a loosely coupled 12V AC rail found in industrial and commercial lighting applications.  The small SOT-23 package allows LEDs to be placed into small-form factor light bulbs to offer higher efficiency versus the traditional halogen and incandescent sources for illumination.

The LM3401 is a high-efficiency hysteretic PFET switching controller that provides a high-performance, constant current drive to a string of LEDs resulting in a constant color output. An adjustable hysteretic window allows for flexibility in component selection and overall design simplicity. Offered in an 8-pin mini SOIC package, the LM3401 has programmable over current voltage protection and a DIM input pin for PWM inputs to control dimming.

The LM3405A extends the voltage range of National's previously announced LM3405 up to 22V. Offered in a tiny 6-pin SOT-23 package, the LM3405A constant-current buck regulator delivers up to 1A of current to drive 3W or 5W LEDs. With a 0.2V reference voltage for constant-current feedback control, internal compensation and a fixed 1.6 MHz switching frequency, the LM3405A provides a simple, highly-efficient solution for driving LEDs. 

It also includes an EN/DIM pin for pulse-width-modulation (PWM) dimming. The LM3405A drives general illumination for industrial and commercial lighting applications from the 12V AC and 12V DC rail.