Sunday, July 17, 2011
NUD4700 Active Shunt Regulator as a Low-Cost Way to Ensure LED Reliability When lighting equipment is mission-critical, ensuring its long useful life is absolutely necessary (examples include headlights, lighthouses, bridges, airport runways, etc.). In the past few years, serial LED networks have been actively used for these purposes. However, failure of a single LED light causes the entire series to fail as well. ON Semiconductor offers a low-cost solution that ensures uninterrupted operation of a LED networks even after one the lights burn out. It can be achieved by connecting NUD4700 active shunt regulators in parallel to each LED. When an LED burns out, the shunt regulator is connected to the circuit, allowing the current to bypass the burnt-out light. NUD4700 shunt regulators are intended for use in parallel with LEDs and come in POWERMITE casings with two terminals for surface mounting. An electronic shunt regulator consists of a thyristor and a control circuit that includes a voltage reference diode and a resistor voltage splitter. A capacitor in the thyristor control electrode circuit ensures reaction delay and prevents false triggering. If a burnt-out LED is replaced with a functioning one, the NUD4700 shunt regulator is switched to the off state, which means it is fully recovered and ready for use again. The circuit must be connected in the following manner. The NUD4700 active shunt regulator is connected in parallel to each LED, which enables the entire network ...
http://www.youtube.com/watch?v=bTKB8P5qIzc&hl=en
