PCB design considerations in power management
With the rapid development of technological products, the PCB design of power supply products is facing greater challenges, including power conversion efficiency, thermal analysis, power plane integrity and EMI (electromagnetic interference), etc.
As industry applications become more extensive and diversified, power supply products continue to develop in the direction of high frequency, high efficiency, high density, low voltage, high current and diversification. At the same time, the packaging structure and external dimensions of power supply products are becoming increasingly standardized to adapt to the requirements of the global integrated market.
The first is power conversion efficiency.
The first is power conversion efficiency. Conversion efficiency refers to the ratio of the output power of a power supply to the actual input power consumed. In practical applications, electrical energy cannot be completely converted, and there will be a certain amount of energy consumption in the process. Therefore, no matter what kind of circuit, there must be efficiency problems in power conversion. . For linear power supplies, the heat dissipation problem of the LDO needs to be considered; for switching power supplies, the loss of the switching tube must be considered.
Secondly, if there is energy loss, heat will inevitably be generated, which involves the issue of heat dissipation. In addition, as the load becomes heavier, the power consumption of the power supply chip increases. Therefore, heat distribution is an issue that must be considered in power supply design.
The third is the power plane integrity design. Maintaining the integrity of the power supply means maintaining a stable power supply. In real systems, there are always noises of different frequencies. For example, the natural frequency of PWM or PFM variable frequency control signal, fast di/dt will produce current fluctuation signal, so a low impedance power plane design is necessary.
Finally, there is the issue of EMI (electromagnetic interference). The switching power supply will generate switching noise when it is constantly turned on and off. If the loop inductance is not considered during the design process, an excessively large return path will cause EMI problems.
The industry has been looking for ways to improve the success rate of power supply PCB design. Experience shows that if possible risks can be predicted in advance and avoided during the design process, the success rate will be greatly improved. Therefore, choosing a suitable design simulation tool is particularly important.