All switching power supply components shall be located on the same side of the board and shall be connected to forward current paths without heat release and without the use of through holes. Grounded through holes should also be connected to a plane without heat release. The output of the switch is called the SW node and is part of the forward AC current path. It has fast switching, high amplitude voltage swing and peak current. In particular, the connection needs to be kept as short as possible.
At the controller level, it is important that this connection have a very low inductance, and that it be wide enough to allow the current flowing through it. Expanding the connection to compensate for the longer distance is not recommended. This is because the likelihood of such a connection becoming an antenna and radiating is directly related to its length. The switcher circuit should be placed so that the connection is away from other circuits, including other switchers on the same board.
The last aspect of the switcher we will look at is the control circuit. The control circuit determines the duty cycle, which in turn determines the output voltage. Duty cycle control signals can be provided by a fully integrated power controller or, more simply, a gate driver that carries switching frequencies. The trace carries medium current and should be far away from the high current loop. It should also be kept away from any sensitive circuits that it might affect. This signal may also need to be pairwise routed with another signal output from the driver to the power switch to reduce the loop area and provide common mode noise suppression. The above is the switching power supply manufacturer Qidong Weiming computer factory finishing.
