Linear Technology Corp. (LTC) has developed the LT3476, a 2-MHz dc-to-dc converter that's designed to operate as a four-channel constant-current LED driver. Each channel can drive up to eight 1-A LEDs in series, enabling the part to drive up to 32 1-A LEDs while delivering efficiencies up to 96%.
Each of the part's four channels is operated by an independent true-color PWM signal, enabling each channel to be dimmed independently to ratios as high as 1000:1. A fixed-frequency, current-mode architecture ensures stable operation over a wide range of supply and output voltages. A frequency-adjust pin lets the user program the frequency between 200 kHz and 2 MHz to optimize efficiency while minimizing external component size. The LT3476 is housed in a thermally enhanced 5- by 7-mm QFN package.
The LT3476 senses output current at the high side of the LED, enabling buck, buck-boost, or boost configurations. With an external sense resistor, the user programs the output current range of each channel. Other features include open LED protection and thermal limiting. Pricing in lots of 1000 starts at $4.64. For more information, visit www.linear.com.