onsemi (Ansemi)

plug-in

Tube

50

The NCP1077A and NCP1077B products integrate a fixed frequency current mode controller with 700 V MOSFETs. Outputting on two different pins in the very common PDIP™7 package, it offers a high degree of integration including soft start, frequency dithering, short circuit protection, cycle skipping, maximum peak current set point, slope compensation and dynamic self-power ( No auxiliary winding required). Unlike other monolithic solutions, the NCP1077A and NCP1077B are noiseless: during normal load operation, the part switches at a usable frequency (65 or 100 kHz). When the demand for output power disappears, the IC will automatically enter frequency foldback mode, providing excellent energy efficiency at light loads. When power demand decreases further, it enters skip mode, reducing standby power consumption to no-load conditions. Protection features include: timers to detect overload or short circuit events, overvoltage protection with automatic recovery. Input line voltage detection prevents severe runaway under low input voltage conditions (undervoltage) as well as over high input lines (AC line overvoltage protection). This also enables the overpower protection to compensate for any internal delays at high input voltage conditions, optimizing the maximum output current capability. To improve standby performance, connecting an auxiliary winding stops DSS operation, helping to reduce input power consumption on the high line to less than 50 mW.