NCP1205

The NCP1205 combines a true Current Mode Control modulator and a demagnetization detector to ensure full Discontinuous Conduction Mode in any load/line conditions and minimum drain voltage switching (QuasiResonant operation, also called critical conduction operation). With NCP1205's inherent Variable Frequency Mode VFM), the controller decreases its operating frequency at constant peak current whenever the output power demand diminishes. Associated with automatic multiple valley switching, this unique architecture guarantees minimum switching losses and the lowest power drawn from the mains when operating at noload conditions. Thus, the NCP1205 is optimal for applications targeting the newest International Energy Agency (IEA) recommendations for standby power.

The internal HighVoltage current source of NCP1205 provides a reliable charging path for the VCC capacitor and ensures a clean and short startup sequence without deteriorating the efficiency once off.

The continuous feedback signal monitoring implemented with an OverCurrent fault Protection circuitry (OCP) makes the final design rugged and reliable. An internal Over Voltage Protection (OVP) circuit continuously monitors the VCC pin and stops the NCP1205 IC whenever its level exceeds 36 V. The DIP14 offers an adjustable version of the OVP threshold via an external resistive network.