The NCP101X series integrates a fixed--frequency current--modecontroller and a 700 V MOSFET. Housed in a PDIP--7,PDIP--7 Gull Wing, or SOT--223 package, the NCP101X offerseverything needed to build a rugged and low--cost power supply,including soft--start, frequency jittering, short--circuit protection,skip--cycle, a maximum peak current setpoint and a DynamicSelf--Supply (no need for an auxiliary winding).Unlike other monolithic solutions, the NCP101X is quiet by nature:during nominal load operation, the part switches at one of the availablefrequencies (65 -- 100 -- 130 kHz). When the current setpoint fallsbelow a given value, e.g. the output power demand diminishes, the ICautomatically enters the so--called skip--cycle mode and providesexcellent efficiency at light loads. Because this occurs at typically 1/4of the maximum peak value, no acoustic noise takes place. As a result,standby power is reduced to the minimum without acoustic noisegeneration.Short--circuit detection takes place when the feedback signal fadesaway, e.g. in true short--circuit conditions or in broken Optocouplercases. External disabling is easily done either simply by pulling thefeedback pin down or latching it to ground through an inexpensiveSCR for complete latched--off. Finally soft--start and frequencyjittering further ease the designer task to quickly develop low--cost androbust offline power supplies.For improved standby performance, the connection of an auxiliarywinding stops the DSS operation and helps to consume less than100 mW at high line. In this mode, a built--in latched overvoltageprotection prevents from lethal voltage runaways in case theOptocoupler would brake. These devices are available in economical8--pin dual--in--line and 4--pin SOT--223 packages.