LED Driver Circuit

Since we know that LED requires specialized devices called LED drivers to operate. So the LED driver provide LED with electricity they require to function and perform at their best. It also protect LED from voltage or current fluctuation. Changing in voltage could cause changing in current being supplied to the LEDs. So the LED light output is proportional to its current supply, and LED are rated to operate within a certain current range. Therefore, too much or to little current can cause light output to vary or degrade faster due to higher temperatures within the LED. For our LED transmitter circuit we used the circuit that recommended from the SFH757V data sheet as shown in Figure. In this circuit as shown in the figure we used a Texas Instruments peripheral driver for high current switching at high speeds which is good for applications like optical transmission especially for LED driver circuit. As in the circuit the two capacitors are for filtering and a 1k resistor is a pull up resistor which is for a stable high level on one of the two inputs of the used AND gate (chip). And then the 50ohm resistor is to reduce reflections between data source and input port of the used AND gate. The R_ILED is very important in this circuit which limits the current through the LED. When we connect the circuit it is very important to take extra care with the LED connection. If we connect with the wrong pin then we could easily blow up the LED. And also the supply voltage as well it is necessary to read the LED data sheet and supply the voltage which is recommended.