Switching Power Supply Using MC33374

This switching power supply circuit diagram is based on the MC33374 high power voltage switching regulator IC manufactured by Motorola Semiconductor. This MC33374 switching power supply circuit will provide a maximum output power around  90 W and require few external components .

The MC33374 switching regulator IC is a monolithic high voltage power switching regulators that combine the required converter functions with a unique programmable state controller .

The MC33374 switching regulator IC is designed to operate directly from a rectified AC line source, and in flyback converter applications are capable of providing an output power in excess of 150 W with a fixed AC input of 100 V, 115 V, or 230 V, and in excess of 90 W with a variable AC input that ranges from 85 V to 265 V.

Circuit Diagram: 




The MC33374 switching regulator offers features like  : Programmable State Controller , On–Chip 700 V SENSEFET Power Switch Circuit , Rectified AC Line Source Operation from 85 V to 265 V , On–Chip 700 V Active Off–Line Start–Up Circuit , Latching PWM for Double Pulse Suppression , Cycle–By–Cycle Current Limiting , Input Undervoltage Lockout with Hysteresis, Non–Latching Internal Thermal Shutdown .

This MC33374 switching power supply circuit has a efficiency of 83.2 % at 115 V AC input voltage and a 85.4 % efficiency at 230 V with  IO= 6 A.

The output voltage of this switching power supply is 15 volts and the maximum output current is 6 A .

The hard part of these switching power supply circuit is   to design the T1 transformer  , but you have the design data for that bellow , or you can buy a transformer from Coilcraft.

Z1 is a zenner diode and is used to limit the voltage on Pin 5 and a damper circuit consisting of resistor R2 and capacitor C2.

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