Saturday, 25 October 2014

LED Driver

This lesson will teach you

What are LEDs ?

Why LED gets fuse or short (Damage) ?
How to use LED in a circuit ?
Learn about LED Driver.

LED (Light Emitting Diode) are small light sources that become illuminated by the movement of electrons through a semiconductor material. It needs low power. Like general diode it allows current to flow in one direction.
The current flowing in an LED is an exponential function of voltage across the LED. A small change in voltage can produce a huge change in current so always add a suitable value of resistance in series with the LED.
Now days high power LEDs and Surface mount LEDs are also available in Electronic Market.
For a good life of LED, use a suitable value of resistance according to source voltage or a LED Driver(Regulated Power Supply).
A LED driver is an electrical device that regulates the power to an LED or string(s) of LEDs. It supplies a constant amount of power to the LED even if source voltage changes.
 
Resistance Value Commonly used for lighting a single  red, green and yellow L.E.D
230V AC –> 82K 1/2 watt
110V AC –> 47K 1/4 watt
12V DC –> 1 K Ohm
9v DC –>470 ohms
6v DC –>330 Ohms
3v DC –>220 Ohms
VOLTAGE REGULATOR : To maintain a steady voltage the resistance of the regulator varies in accordance with the load resulting in a constant output voltage. The regulating device is made to act like a variable resistor, continuously adjusting a voltage divider network to maintain a constant output voltage.