The circuit shown in the schematic below is a typical implementation of a 12 V – 120 mA non-isolated power supply that can be used in appliance control such as rice cookers, dishwashers, or other white goods. This circuit may also be applicable to other applications such as night-lights, LED drivers, electricity meters, and residential heating controllers, where a non-isolated supply is acceptable.
Resistor R5 controls inrush current at a safe level for D2/D5, D2/D5 converts AC supply into DC, inductor L1 for EMI noise, Capacitor C3-C4 DC filter capacitor. The power processing stage is formed by the Link-Switch, freewheeling diode D4, output choke L2, and the output capacitor C5. The LNK3204 was selected such that the power supply operates in the mostly discontinuous mode (MDCM).