Compact size and low cost DC-DC converters | AC-DC converters | DC-AC inverters | step up converter

AC-DC Switching Power Application Notes

When using AC / DC power modules, user should pay attention to the following aspects:

1. Choice of output current

Ordinary linear power efficiency is 35% ~ 40%, therefore, if original solution adopted a linear power supply (a transformer) of 45VA, replace with a 15W power supply module may be sufficient. However user should estimate maximum current absorption as accurate as possible, and generally remain about 80% margin (depends on the specific applications), which is used then to determine the rated output current of the power module.

2. Interference suppression measures

Switch mode AC / DC power supply generate more interference than the linear regulator. It will not have any impact on general electrical systems. But for common-mode interference sensitive circuitry, attention should be paid to take ground shielding measures. Conneting AC / DC power module's GND to earth or termination case can achieve very good results.

3. Earthing measures

By ICE1000, EN61000 and FCC standards etc EMC requirements, switch-mode power supply should adopt EMC measures. Therefore, power modules usually have EMC filters. While in use, GND must be well connected to the earth in order to meet the electromagnetic compatibility requirements.

4. Overload and fault protection

In the design of power supply modules, designers have considered account in the general running overload, and overheating, over-current, short circuit protection and so on. Devices should be able to bear the load current 10 times a few minutes. If internal temperature rise too high or output is short-circuit, it will automatically cut off power supply in order to avoid damage, after correction of failure it will automatically recover.