Electronica

LEDS
Selecting the best topology for white LED drive electronics

[pic]
| | | | |
|BIncandescent |3% |No |2,000 hrs |Warm,Yellowish 9 |
|I Fluorescent | |Yes |7,500 hrs.|Cold,Blueish 1 |
|I LED |12%-20% |No |50/ |Anything 1 |
|Table 1: Competing Light Technologies|

-o
PI-37SS-181003
Figure 1: Basic configuration of a LinkSwitch-TN as a) a buck converter and b) a buck-boost converter
BySilvestro FimianiProduct Marketing Mngr.-Appliance and Industrial Applications Power Integrations, Inc.

The incandescent light bulb's days are numbered. Over the last century Edison's traditional filament-baseddesign has stood the test of time and become the standard for general illumination applications. But new lighting technologies, in particular light-emitting diodes (LEDs), promise to eventually displaceglass-encased incandescent bulbs as well as fluorescent lights.
In a world where escalating costs have every user closely examining power budgets, incandescent technology finds itself on the wrongside of the power efficiency curve. Approximately 97 percent of the energy consumed by an incandescent bulb is wasted in heat. Fluorescent bulbs offer a slightly better option, but still waste up to 85percent of power consumed. Moreover, both technologies last on average only about 5000 hours before needing replacement. Fluorescent technology also uses toxic Mercury and emits a harsh-colouredlight. Neither technology can compare to white LEDs which offer a lifecycle ten times as long, do not use toxic materials and can support virtually any colour light. Most importantly, LEDs support light...