A typical line connected power supply must perform the following functions (in this specific order):
- Voltage conversion – changing the 115/230 VAC line voltage into one or more other voltages as determined by application.
- Rectification – turning the AC into DC.
- Filtering – smoothing the ripple of the rectified voltage(s).
- Regulation – making the output voltage(s) independent of line and load variations.
- Isolation – separating the supply outputs from any direct connection to the AC line.
A power supply is often taken very much for granted, especially in a PC. “That little box at the back with the fan in it” has a very important job to do!