What points should you pay attention to when choosing switching power modules?
Switching power supply in the input anti-interference performance, due to the characteristics of its own circuit structure (multi-level series), the general input interference such as surge voltage is difficult to pass, in the output voltage stability of the technical index compared with the linear power supply has a greater advantage, its output voltage stability can reach (0.5 ~ 1) %. Switching power module as a power electronic integrated device, in the selection should pay attention to the following points:
1 Selection of output current
Because the switching power supply work efficiency is high, generally can reach more than 80%, so in the selection of its output current, should accurately measure or calculate the maximum absorption current of the electrical equipment, so that the selected switching power supply has a high performance-to-price ratio, usually the output calculation formula is:
Is=KIf
Where: Is – rated output current of switching power supply;
If – the maximum absorbed current of the electrical equipment;
K – margin coefficient, generally 1.5 ~ 1.8;
2 Grounding
Switching power supply than linear power supply will produce more interference, common mode interference sensitive electrical equipment, should take grounding and shielding measures, according to ICE1000, EN61000, FCC and other EMC restrictions, switching power supply are taken EMC EMC measures, so the switching power supply should generally have EMC EMC filter. For example, Leadworth technology’s HA series switching power supply, its FG terminal is connected to the ground or to the user’s housing, in order to meet the above electromagnetic compatibility requirements.
3 Protection circuit
Switching power supply in the design must have overcurrent, overheating, short circuit and other protection functions, so in the design should be preferred with complete protection of the switching power module, and the technical parameters of its protection circuit should be matched with the working characteristics of the electrical equipment, to avoid damage to the electrical equipment or switching power supply.