National Semiconductor has introduced an LED driver to drive three common anode RGB high-brightness LEDs sequentially with a single inductor. The LM3435 LED driver includes an I2C control interface for LED current control. It powers one LED after another at a frequency of 60Hz and above to match the operation requirements of the liquid crystal on silicone or digital light processing image devices.
The LED driver integrates all active components, including an N-channel main MOSFET, P-channel synchronous MOSFET and three N-channel pass switches for individual LED control. It accepts input voltage from 2.7 to 5.5V to drive constant current pulses to each red, green and blue high-brightness LED sequentially. The level of current pulses is individually programmed linearly for 1023 steps through an I2C interface. The maximum level of the current pulse can be set by three external current setting resistors to ground from 0.5 to 2.0A. The driver's non-isolated flyback converter with synchronous rectification ensures buck-boost operation at high efficiency.
