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Selecting a power supply module is not simple; many challenges must be taken into account. How much do you know about this? Choke coils, capacitors, diodes, resistors… all have similar underlying principles, it’s just that people don’t pay much attention to them. There are a variety of topologies for power supply modules, including flyback, forward, push-pull, half-bridge, and full-bridge. Each of these has advantages in terms of certain specific performance metrics, due to the differences in their underlying principles. In a flyback power supply, during one cycle of the power switch, there is no charging or discharging activity while the battery is being charged. As a result of this characteristic, it is not possible to achieve very good performance in terms of response time and ripple reduction. Although large capacitors used for energy storage can help to some extent, this fundamental limitation remains a drawback. It has issues such as high leakage inductance, but its advantages include a simple power supply circuit, low cost, light weight, no need for magnetic calibration windings, and a wide operating voltage range. It is for this reason that it holds a market share of around 70% of the total power supply market. The forward-powered supply has good transient control characteristics for its output voltage, as well as a high load capacity. However, its drawbacks are equally evident: it requires a large energy-storing filter inductor and a freewheeling diode; it has a large volume, the back-emf voltage of the transformer’s primary coil is high, which imposes high requirements on the switching transistors. The push-pull power supply has a very high transient response time for current, excellent frequency characteristics at the operating voltage, and is the most widely used type of power transformer among all topologies; it has no magnetic leakage and a simple optocoupler circuit.