chapter  22
16 Pages

AC Driving Circuits for LEDs

Apart from the above thoughtfulness, in order to account for the dierent frequency norms (50 or 60 Hz), the AC driving circuits are designed to

operate from 47 to 63 Hz. Further, AC drive circuits must be endowed with EMI and surge protection (Zywyn ZD832 2007). e device should assure fortication against LED string fault (open or short). Provision should be made for protection features such as auxiliary winding disconnection or brownout (reduction/cutback in electric power) detection and shorted secondary rectier or transformer saturation detection (STMicroelectronics 2010). Many products include features such as overcurrent protection when the current exceeds a predecided limit, short-circuit protection in the event of short circuiting or overloading, overvoltage protection against high voltages, overtemperature protection at elevated temperatures, lightning protection in case of a lightning strike, and so on.