NCP1215

Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected.

The NCP1215 is a controller for low power off−line flyback Switchemode Power Supplies (SMPS) featuring low size, weight and cost constraints together with a good low standby power performance.
The operating principle of NCP1215 uses switching frequency reduction at light load by increasing the OFF Time. Also, when OFF Time expands, the peak current is gradually reduced down to approximately 1/4 of the maximum peak current to prevent from exciting the transformer mechanical resonances.

The risk of acoustic noise is thus greatly diminished while keeping good standby power performance. A low power internal supply block also ensures very low current consumption at startup without hampering the standby power performance. A special primary current sensing technique in NCP1215 minimizes the impact of SMPS switching on control IC operation.

The choice of peak voltage across the current sense resistor allows dissipation to be further reduced. The negative current sensing technique offers advantages over a traditional approach by avoiding the voltage drop incurred by traditional MOSFET source sensing. Thus, the NCP1215 IC drive capability is greatly improved. Finally, the bulk input ripple ensures a natural frequency dithering which smooths the EMI signature.