onsemi (Ansemi)

SOIC-7

taping

2500

The NCP1240 is a new fixed-frequency current-mode controller with dynamic self-power 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 supports brown-out detection. It features timer-based fault detection to ensure overload detection and adjustable 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 robust power supply designs. A dedicated shutdown mode achieves extremely low no-load input power consumption by putting the entire device to "sleep", thereby minimizing power consumption in the control circuitry. The NCP1240 adopts dual-level overcurrent protection, which is different from other fixed-frequency flyback controllers with active X2 discharge and high-voltage startup. For some applications, such as limited power supplies, the controller must maintain regulation when it detects an overload on the first stage. This allows the transient peak power to be higher than the maximum continuous output power. This product complies with the IEC60950 standard. See test reports and certifications in the Compliance Reports section below.