How to layout and select switching power supplies
Switching power supply is a highly efficient power converter, with a theoretical value close to 100% and a wide variety of types. According to the topology structure, there are Boost, Buck, Boost Buck, Charge pump, etc; According to the switch control mode, there are PWM PFM; According to the type of switching transistor, there are BJT, FET, IGBT, etc. This discussion focuses on the commonly used PWM control Buck and Boost types for data card power management.
The main components of a switching power supply include: input source, switching transistor, energy storage inductor, control circuit, diode, load, and output capacitor. At present, the vast majority of semiconductor manufacturers integrate switch tubes, control circuits, and diodes into a power management IC with CMOS/Bipolar technology, greatly simplifying external circuits.
The energy storage inductor, as a key component of the switching power supply, plays an important role in the performance of the power supply and is also a key focus and debugging object for product design engineers. With devices like smartphones PMP, The size of consumer electronic devices represented by data cards is developing towards a trend of light, thin, compact, and fashionable, which is contradictory to the larger capacity and size of inductors and capacitors required for stronger product performance. Therefore, how to reduce the size of the switching power supply inductor (occupied PCB area and height) while ensuring product performance is an important topic to be discussed in this article. Designers will have to compromise between circuit performance and inductor parameters (Tradeoff).
Everything has two sides, and switching power supplies are no exception. Bad PCB layout and wiring design not only reduces the performance of switching power supplies, but also strengthens EMC EMI, Grounding, etc. Another important topic to be discussed in this article is the issues and principles that should be paid attention to when laying out and wiring switch mode power supplies.
