Variable Cost Low Off Time Switching Power Supply Controller The NCP1215 is a low power off-line flyback controller Switchemode Power Supply (SMPS) with low size, weight and cost constraints and good low standby power performance. Using the principle of switching the light frequency reduces the load and increases the shutdown time. Furthermore, when the off time is expanded, the peak current is gradually reduced to about 1/4 of the maximum peak current to prevent mechanical resonance from the exciting transformer. The risk to noise is greatly reduced while maintaining good standby power performance. A low power internal power block also guarantees very low current consumption at startup without hindering backup power performance. A special primary current sensing technique minimizes the effect of switching the power switch's control IC operation. The voltage across the selected current sense resistor for this peak is allowed to dissipate further down. The negative current sensing technique offers the advantages over a conventional method, avoiding the voltage drop incurred by the source sensing of conventional MOSFETs. Therefore, the chip driver capability is greatly improved. Finally, the large input ripple guarantees natural frequency jitter and its smooth EMI signature.

Features • Lead-free package available • Variable off-time control method • Very low current consumption at startup • Natural frequency jitter for improved EMI signature • Current mode control operation • Peak current compression reduces transformer noise • Programmable peak voltage current sense resistor • Typical Applications of Under-Voltage Lockout • Auxiliary Power • Backup Power • AC-DC Adapter • Offline Battery Charger