Housed in SO-8 or DIP8 package, the NCP1203 represents a major leap toward ultra-compact Switch-Mode Power Supplies and represents an excellent candidate to replace the UC384X devices.Thanks to its proprietary SmartMOS Very High Voltage Technology, the circuit allows the implementation of complete off-line AC/DC adapters, battery charger and a high-power SMPS with few external components.With an internal structure operating at a fixed 40 kHz, 60 kHz or 100 kHz switching frequency, the controller features a high-voltage start-up FET which ensures a clean and loss-less start up sequence. Its current-mode control naturally provides good audio susceptibility and inherent pulse-by-pulse control.When the current set point falls below a given value, e.g. the output power demand diminishes, the IC automatically enters the so-called skip cycle mode and provides improved efficiency at light loads while offering excellent performance in standby conditions. Because this occurs at a user adjustable low peak current, no acoustic noise takes place.The NCP1203 also includes an efficient protective circuitry which, in presence of an output over load condition, disables the output pulses while the device enters a safe burst mode, trying to restart. Once the default has gone, the device auto-recovers. Finally, atemperature shutdown with hysteresis helps building safe and robust power supplies.