LEDs have already replaced traditional incandescent lamps in traffic signal applications for their high efficiency, low power consumption and long life. LED Traffic Signals use both high brightness & high power LEDs connected in a combination of series and parallel to build a LED cluster. To realize specific luminous distribution intensity, an additional optical design (lenses) is necessary. If traffic signals are driven by AC power, an AC-DC circuit is required to convert AC to DC power that is suited for LED driver to drive LED cluster/string. MCU is used to implement the control over LED driver so as to give correct traffic signals.