How to design a good switching power supply module?
2022-08-25

First, evaluate the module power requirements of the system

For the electronic system, the module power demand not only focuses on the input voltage, output voltage and current, but also considers the power consumption, power efficiency, transient response of power to load changes, tolerance of key equipment to power fluctuations, allowable power ripple and heat dissipation. Power consumption and efficiency are closely related, with high efficiency. When the load power consumption is the same, the total power consumption is small. LDO and switching power supply module, the efficiency of switching power supply module is higher. When looking at the efficiency of the full load power circuit, we should also pay attention to the efficiency of light load.

Switching power supply module

As for the load transient response capability, there are strict requirements for some high-performance CPU applications, because when an application is a CPU and a heavy task suddenly starts to run, the required startup current is very large. If the response speed of the power supply circuit is not enough, and the instantaneous voltage drops too much or too low, it will lead to CPU operation error. Large current power supply and heat dissipation LDO more importantly, it can also be evaluated through calculation.

How to select the appropriate power module circuit?

According to the specific technical indicators obtained by analyzing the system requirements, the appropriate circuit can be selected. Generally speaking, the weak current part includes LDO (linear power converter), switching power supply capacitor buck converter and switching power supply inductor capacitor converter. In contrast, LDO design is the easiest to realize, with small output ripple, but its disadvantages are low efficiency, large heat value, and less current than switching power supply. The circuit design of switching power supply is flexible and efficient, but the ripple is large, the implementation is complex and the debugging is cumbersome.

How to select the appropriate components and parameters for the switching power supply module?

Many engineers who do not use the modular power supply design will have some fears about it, such as the interference of the switching power supply module, the pcbayout problem, and the parameter and type selection of components. In fact, as long as you understand, the design is very convenient to use, which not only simplifies the PCB design, but also makes the design more flexible. The switching controller is basically a closed-loop feedback control system, so there is usually a sampling circuit for feedback output voltage and a control circuit for feedback loop. Therefore, the design of this part is to ensure accurate sampling circuit and control feedback depth. If the response of the feedback loop is too slow, the transient response capability will be greatly affected.