Power chip

The products NCP1075A and NCP1075B integrate a fixed frequency current mode controller and 700 V MOSFET. Using the very common PDIP 7 encapsulation, with two different pin outputs, provides a high level of integration, including soft start, frequency jitter, short circuit protection, skip cycle, maximum peak current set point, slope compensation and dynamic self-power supply (DSS, no auxiliary winding required). Unlike other monolithic solutions, the NCP1075A and NCP1075B are noiseless: during normal load operation, when switching at one of the available frequencies (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 NCP1246 is a new fixed-frequency current-mode controller with dynamic self-supply capability. This feature activates the internal start-up current source to power the controller during start-up, transients, latch-up, standby, etc., greatly simplifying the design of auxiliary power supplies and VCC capacitors. The device contains a special high voltage detector that detects the application of unplugging from the AC line and triggers the X2 discharge current. The high voltage structure also includes an undervoltage detection circuit. The NCP1246 features timer-based fault detection to ensure overload detection and adjustable power compensation to help maintain maximum power regardless of input voltage. Due to frequency foldback, the controller has excellent energy efficiency at light load conditions while achieving very low standby power consumption. Internal frequency jittering, slope compensation, and a multifunction latch input make this controller an excellent candidate for rugged power supply designs. A dedicated shutdown mode enables this SMPS to achieve very low no-load input power consumption when used with the auxiliary side controller NCP4353 or NCP4354. When used together, the SMPS is capable of <10 mW no-load input power dissipation. The secondary side controller signals the NCP1246 to enter sleep mode, minimizing the power consumption of the control circuit. This product complies with the IEC60950 standard. See test reports and certificates in the Compliance Reports section below.