Power chip

The NCP1076A and NCP1076B products integrate a fixed frequency current mode controller with 700 V MOSFETs. It has two different pin outputs, adopts very common PDIP™7 encapsulation, highly integrated, including soft start, frequency dithering, short circuit protection, skip cycle, maximum peak current set point, slope compensation and dynamic self-power supply ( No auxiliary winding required). Unlike other monolithic solutions, the NCP1076A and NCP1076B 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 automatically enters frequency foldback mode, providing excellent 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. AC input line voltage detection prevents severe runaway under low input voltage conditions (brownout) as well as over high input line (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.

The NCP1361 provides a novel solution aimed at achieving output power levels from a few watts to 20 W in general power supply flyback applications. Thanks to the new approach, the new controller eliminates the need for an auxiliary feedback circuit for constant current regulation, while achieving excellent line and load regulation using a conventional optocoupler and TL431 voltage reference. The NCP1361 operates in a valley-lock quasi-resonant peak current control mode at high loads to provide high energy efficiency. When auxiliary side power starts to disappear, the controller will automatically adjust the duty cycle, then at lower loads, the controller goes into pulse frequency modulation with a fixed peak current through valley switching detection. This technique allows output regulation to be maintained under small dummy loads. Valley lockout in the first 4 valleys prevents valley skipping operation, then valley switching at lower loads provides high energy efficiency.