High brightness LEDs are bringing about a revolution in lighting, especially at the front of automobiles. There are still cost-benefit tradeoffs; only with long lifespan can HB-LEDs be justified in cost-sensitive automotive applications.
Operating temperature is the main factor when it comes to longevity. To improve it, the driver can also provide features such as dimming, fault protection and the ability to control multiple strings of LEDs.
HBLEDs can win out in most applications, if their prospective lifetime can be achieved and this comes down to effective thermal management. LEDs rarely fail abruptly under normal conditions, but lose brightness due to propagation of lattice defects (called “dislocations”). A typical plot of lifetime against HBLED chip temperature is shown here:
Fundamental to maintaining chip temperature within design limits is the driver IC specified, but the application also dictates the type of driver needed. A controlled current source is often the best solution.