In short, the switching power supply works by
When the ac power is input, it usually goes through something like the earthen coil to filter the interference on the power grid and the interference from the power supply to the power grid.
With the same power, the higher the switching frequency, the smaller the volume of the switching transformer, but the higher the requirements of the switching tube;
The secondary of a switching transformer may have multiple windings or a winding may have multiple taps to obtain the desired output;
Generally also should add some protection circuit, such as no load, short circuit and other protection, otherwise it may burn the switch power supply.
This is the general working principle of switching power supply.
In fact, now has a very high level of integration of the special chip, can make the peripheral circuit is very simple, even do not debug.
The development of computer switching power supply has gone through AT, ATX, ATX12V three development stages.The AT standard was proposed by IBM in the early launch of PC/AT machines, providing + 5V, -5v, + 12V, -12v four sets of voltage, with a hard switch.The generation of ATX standard is of epoch-making significance, which realizes the soft boot and shutdown, can wake up through the remote network, and adds +3.3V, +5VSB output. ATX12V is the product of hardware development such as CPU, which mainly increases the output capacity of +12V.