onsemi (Ansemi)

SOIC-7

taping

2500

The NCP1247 is a novel fixed-frequency current-mode PWM 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 the auxiliary power supply and Vcc capacitor. 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 NCP1247 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 NCP1247 to enter sleep mode, minimizing the power consumption of the control circuit. The NCP1247 is very similar in function to the NCP1246. The NCP1247 brings higher performance to systems with synchronous rectification. NCP1247 - Added C and D options for different undervoltage thresholds - Enhanced operation of synchronous rectification at light loads - Modified X2 discharge sequence This product is IEC60950 compliant. See test reports and certificates in the Compliance Reports section below.