Topology mainly affects the conversion efficiency, dynamic capability and stability of power supply.

But there is no fixed collocation relationship between the topology and the power supply.

And the topological structure is very detailed in classification, just like a tree graph, which can be divided into forward excitation, full bridge and half bridge.

Switching power supply has six topologies, the order is buck/boost/buck-boost/cuk/zeta/sepic, and the most basic topology is: buck/boost/buck-boost。

Buck topology circuit:

Switch T tube connection :

Switch T tube disconnection：

When the T tube is on, the current on the PWM drive increases linearly. At this time, in addition to supply to the load, there is a part of the electric energy stored in the inductor PWM and capacitor C.

Boost topological circuit

Boost - type circuit topology, sometimes called step-up circuit.

Switch T tube connection :

Switch T tube disconnection：

Buck-Boost topological circuit

The polarity of the input voltage and the output voltage in a buck-boost circuit is opposite.

Switch T tube connection :

Switch T tube disconnection：

It should be noted that since the startup current of a buck-boost circuit is larger than that of a BUCK circuit, some buffer-type devices are added to the input of the buck-boost voltage.

Among the basic power supply topologies, Buck Buck is the most widely used. However, the combination of various basic topologies can solve many problems similar to the application of positive and negative power supply and bidirectional power supply.

In short, the power base topology is old, but the practical application can be ever-changing.