Do a few years of power board layout, summed up some of the main points of attention, mainly from the following places to consider:

First, the power loop part

Power board is more important to bear the brunt of the power loop part of the layout should be the first time to know the power of the cloth part of the circuit in the power of the power circuit is divided into di / dt circuit and dv / dt circuit, the two circuits In the layout of the line when walking is not the same.

Di / dt circuit because of its unit time changes in the current is relatively large, so this part of the circuit in the line when the focus should be concerned about the entire circuit loop area should be as small as possible, preferably a loop of the line in the Different layers overlap, so that the circuit loop area of ​​the smallest, the interference itself can be coupled on their own out.

Dv / dt circuit its focus is completely different, because this circuit in the unit time voltage changes will be relatively large, so it is easy to interfere with the outside world, so this circuit in the line when the copper can not be too wide, In the case of bearing current, the width of the copper foil is as small as possible, and the overlapping areas of the different layers are as small as possible and the sensitive signals are as far away from these traces as possible.

Second, drive part

Driving the part of the line first to consider the entire drive circuit area, as small as possible, away from the source of interference, from the drive part as close as possible. Like the MOS tube, such as the power of the components of the drive, in the line when the special attention to the G pole and D pole of the alignment do not walk parallel, because in most cases, the MOS pole of the D pole part of the circuit is dv / dt Circuit, G pole is the drive circuit, if the parallel walk, the drive signal is easy to be disturbed, resulting in MOS malfunction.

Third, the sampling signal

Sampling signals like voltage sampling and current sampling in power boards are also critical because these signals are directly related to the control, and all of these sampled signals should try to avoid other signals, if conditional These sampled signals can be sampled by differential, and they can be given a complete ground plane at the corresponding traces.

Four to the ground

The importance of the land, not to mention, no matter what kind of board, for the handling of the ground is very important. In the power board is relatively more complex, because many times the power part of the high current to the ground, control part of some small current are common ground, so this time the processing of these places is very important in my Of the experience to deal with these areas, the key is to choose a correct single point even node, because each power supply design is not the same, so the choice of this single point of connection is not the same, I am in the low-power photovoltaic inverter Are generally selected BUS capacitor of a pin, the inverter I generally is a large current in a capacitor to lead a relatively thick line to the switching power supply input to the capacitor on the pin, And then from the pin to the switch behind the power supply out of those small current ground plane, of course, there are some other places, such as crystal ground, sampling, etc., each company's design rules are not the same The law is not the same, the Internet for the processing of the information is also more.

Five, safety regulations

Safety regulations in the design of power products is indispensable for different countries in different regions of the corresponding safety regulations are also different requirements, as well as the application of environmental pollution levels and altitude will be the safety of the distance to be compared Big impact, all of us at the beginning of the design must be clear above these factors, if there are safety engineers, then they can ask them to give a more professional creepage and electrical clearance distance, we actually PCBLayout time to pay special attention to those metals Components in the area where the PCB, such as the fuse, it is the middle of the metal is non-metallic metal, if there is no seat, then the fuse of the two metal and PCB contact, all the fuse around the surface traces should pay attention to avoid these metal areas.

Six, heat

For those relatively large power system, the heat is also essential, the general circumstances and the structure with a good, in the design to understand the overall structure of the cooling method is natural cooling, air cooling or water cooling, which air-cooled But also sub-suction and hair, which will have a greater impact on the layout.

Seven, electromagnetic compatibility (EMC)

Mainly some of the power part of the alignment width as far as possible not to mutations, if you need to turn, turn the place also try to do a little peace, do not mutations, there is sometimes there will be high current, small current, sampling signal, although some Is to share a network, but when the free line do not share a loop, to go separately, the walk of the circuit is better.