This application note describes several low-cost power supply circuits for home appliance applications. These circuits can be built with simple components and are very cost-effective.
This document describes three methods for powering microcontrollers in home appliances: transformer-based, capacitive, and resistive power supplies. It details the circuit diagrams, advantages, and disadvantages of each approach, noting that transformerless solutions reduce cost and size but lack isolation from the AC line.
The document presents the basic principle and cost analysis of various power supply circuits for home appliance applications.
The 78L05 regulator in the transformer power supply can deliver up to 100 mA.
For a 220V / 50Hz supply, a 1 uF AC capacitor allows a maximum average output current of 22.1 mA.