The NCP1351 is a current−mode controller targeting low power off−line flyback Switched Mode Power Supplies (SMPS) where cost is of utmost importance. Based on a fixed peak current technique (quasi−fixed TON), the controller decreases its switching frequency as the load becomes lighter. As a result, a power supply using the NCP1351 naturally offers excellent no−load power consumption, while optimizing the efficiency in other loading conditions. When the frequency decreases, the peak current is gradually reduced down to approximately 30% of the maximum peak current to prevent transformer mechanical resonance. The risk of acoustic noise is thus
●greatly diminished while keeping good standby power performance.
●Features
●•Quasi−fixed TON, Variable TOFF Current Mode Control
●•Extremely Low Current Consumption at Startup
●•Peak Current Compression Reduces Transformer Noise
●•Primary or Secondary Side Regulation
●•Dedicated Latch Input for OTP, OVP
●•Programmable Current Sense Resistor Peak Voltage
●•Natural Frequency Dithering for Improved EMI Signature
●•Easy External Over Power Protection (OPP)
●•Undervoltage Lockout
●•Very Low Standby Power via Off−time Expansion
●•Internal Temperature Shutdown
●•SOIC−8 Package
