Abstract: Based on the SinoMOS 1μm 40V CMOS process,a CMOS flyback PWM controller with low power consumption is presented.The flyback PWM controller provides frequency conversion-mode under the light-load condition and burst-mode under the zero-load condition,which minimize standby power consumption and enable the power supply to meet international power conservation requirements.The PWM frequency of the flyback PWM controller is 65~66kHz with a normal load and 21.7kHz with no or light load.The start operation current is 17~18μA,and the normal operation current is 3.5~4.0mA.The active die area of the flyback PWM controller is 2.06mm×1.55mm.

Key words: flyback controller, pulse-width-modulation, frequency conversion-mode, burst-mode, CMOS, low power