LEDs are among the most environmentally friendly electronic components available today. The expected life of a properly designed LED lighting assembly can exceed 10-12 years, or 70,000 hours. There are no moving parts to wear out, filaments to be broken or mercury biohazards present. So how, you may ask, can one extend the life cycle of this product?

The first key for maximizing your circuitry and extending the lifecycle of an LED is to correctly size and wire your components. To avoid almost instant burn out, a resistor must be connected in series with LEDs to limit the current.

To calculate the resistor value ‘R’ use the following:

R = (V_S – V_L)/I where:

V_S = Supply Voltage

V_L = LED Voltage

I   = LED Current

Check manufacturer specifications for the applicable LED voltage and current. If the resistor value calculated is not available choose the next larger size to limit the current and protect your LED.

When connecting multiple LEDs it is advisable to wire them in series when possible, as they will share the same current. If parallel connections are to be used, make sure each LED has a resistor in series to limit the current in that leg and protect your device. Always be sure to double-check polarity. While many think the only result of incorrect wiring is a light that doesn’t energize but it is possible to apply a reverse voltage above the typically low reverse breakdown voltage of an LED. This will result in damage to your LED and a reduced lifecycle, if not destruction of the component.

The future opportunities for extending LED life cycles are abundant. I’ve included a couple of the most interesting projects that are closest to completion and implementation.

One of the new developments being researched and tested is using metal-coated silicon wafers. This will reduce costs further and extend the LED life cycle even beyond current abilities. The Applied Physics Letters journal published a study by Purdue Engineers regarding current silicon-based research trials. A reflective metal coating is applied to a silicon wafer. The new metal coating is a thin, reflective layer of zirconium nitride.

Currently, when the LED emits light, that light is emitted in both the up and down directions. The reflective metal coating limits the light lost in the downward direction. This will reduce the LED duty cycle and allow an extended life.

Another method of operating LED circuits through manipulation of the gain control and duty cycle is currently seeking a patent. The higher gain control in this technique results in a duty cycle of less than 100%. This extends LED life by essentially slowing the aging process. This process also includes end-of life predictions for your LED device or entire lighting assembly. Being able to predict and replace LEDs during scheduled maintenance times reduces facility cost and downtime of equipment.

There are many other research projects in place to improve the life cycle and efficiency of light emitting diodes. A variety of these use IC chips for circuit control while others employ new multi-chip technologies.

With copious amounts of research time and money being dedicate to improving the current benefits of LED usage, this is a new and exciting time for this field. Research efforts to further prolong LED life will once again bring new life to this device and expand its use to unknown limits.