Selection and Solution Guides

Application Notes

Thermal Performance of the LM3404/04HV in SO-8 and PSOP-8 Packages (Rev. A)


The LM3404/04HV is a buck-regulator designed for driving high powered LEDs at forward currents of up to 1.0A. LED drivers often experience thermal conditions that are extreme even by the standards of switching converters. For example, LED drivers are often placed on the same metal-core PCB (MCPCB) as the LEDs themselves. At 1.0A, a single-die white LED can dissipate more than 3W. The temperature of the MCPCB can easily reach 60°C or more. Even when the driver is placed on a separate PCB, the combination of high power dissipation, small, enclosed spaces, and little-to-no air flow create high ambient temperatures and even higher junction temperatures.