NCP1360

Low Power Offline Constant Current & Constant Voltage Primary Side PWM Current-Mode Controller with/without High Voltage Startup Current Source NCP1360, NCP1365 The NCP1360/65 offers a new solution targeting output power levels from a few watts up to 20 W in a universal−mains flyback application. Thanks to a novel method this new controller saves the secondary feedback circuitry (opto−coupler and TL431 reference) while achieving excellent line and load regulation. The NCP1360/65 operates in valley−lockout quasi−resonant peak current mode control mode at nominal load to provide high efficiency. When the secondary−side power starts diminishing, the switching frequency naturally increases until a voltage−controlled oscillator (VCO) takes the lead, synchronizing the MOSFET turn−on in a drain−source voltage valley. The frequency is thus reduced by stepping into successive valleys until the number 4 is reached. Beyond this point, the frequency is linearly decreased in valley−switching mode until a minimum is hit. This technique keeps the output in regulation with the tiniest dummy load. Valley lockout during the first four drain−source valleys prevents erratic discrete jumps and provides good efficiency in lighter load situations. Features Primary−Side Feedback Eliminates Opto−coupler and TL431 Reference ±5% Voltage Regulation ±10% Current Regulation 560 V Startup Current Source No Frequency Clamp, 80 or 110 kHz Maximum Switching Frequency Options Quasi−Resonant Operati...