The L6590 is a monolithic switching regulator designed in BCD OFF-LINE technology, able to operate with wide range input voltage and delivering an output power up to 13W. The internal switch. is implemented by a lateral high voltage power Mosfet with an Rdson of 13 and a BVDss of 700V. The internal fixed oscillator frequency, non dissipative start up and the internal soft start system allow to minimize the components count. A 2.5V+/-2% internal reference in addition to a high gain error amplifier make the device suitable for low cost applications with primary control. Internal protections like cycle by cycle current limiting, output overvoltage protection and thermal shutdown generate a 'robust' design solution. The device automatically reduces the frequency from 65KHz to 22KHz under light load conditions improving the efficiency.