Four suggestions for power circuit design

1. Ceramic capacitors can be used with a wide variety of dielectrics, each with different characteristics that can greatly affect performance over its temperature and voltage range. The two most common dielectrics are the Y5V and X5R, while the Y5V dielectric is inexpensive and offers high capacitance in a small package, but its capacitance varies widely over its voltage and temperature range and is not suitable for DC/DC applications.

X5R and X7R dielectrics are more suitable for output capacitor applications because their characteristics are more stable over their operating range and are highly recommended.

2. Proper selection of capacitor and inductor values will make the circuit more stable, but good PCB design is still the key to avoiding high ripple or even self-oscillation.

3. By adding a PI filter, you can better protect the MCU's more ripple-sensitive power supplies (for example, analog voltage references).

4. The power supply margin should be sufficient

The power supply must be left with a margin, which is generally at least 20% more than the peak power consumption of the load. This is safer and will not cause unexpected failures.

When the power supply is insufficient, the power supply will work in the limit state, and the ripple of the power supply will rise sharply, reaching several hundred mV or even several V. So before determining the power input, it is best to estimate the maximum power consumption above the entire board subsystem.