AC to DC switching converters are ICs used in switch-mode power supply circuits to convert an AC input voltage power supply waveform into a regulated DC output power supply. Important characteristics include input voltage range, maximum input current, DC output voltage, maximum peak current and the continuous current the converter can supply to a load. Converters are also characterized by efficiency, typically around be 70-80%.

 

Converters are used in circuit configurations that generally fall into the categories of flyback, buck, boost and buck-boost topologies. They have control circuitry inbuilt to regulate the output power over a wide range of dynamically changing input voltage levels and output impedance loads. They will also typically have fault condition sensing and circuitry to detect if the switcher is being overloaded or the input is under voltage. Some converters have in-built power factor correction circuits to improve the power factor presented to the mains supply. This reduces the burden on the mains supply, increases the efficiency of the switch-mode and reduces the noise created by the mains supply.

 

All switches generate a high-frequency square wave output that needs to be filtered by a reactive element that stores and smoothens out the square wave ripple to produce a DC output. This is usually a capacitive banks or inductive capacitive combination. The remainder of this square wave AC that has not been integrated out by the capacitors is referred to as ripple voltage.