Standby consumption reduction for capacitive power supplies

Most appliances that only require a low current in the range of 10 mA to 50 mA to supply the control circuit still, even today, use capacitive power supplies. In these appliances the MCU usually controls one or two Triacs, one LED and sometimes a buzzer; they are, for example, coffee machines, food processors, room heaters, hand dryers or low-end fridges. It is increasingly difficult to meet standard standby power requirements with such capacitive power supplies. We explain here how capacitive power supplies can be modified to better meet these requirements or to increase their output current capability while maintaining power consumption during standby operation mode at a low level.