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Three performance indicators of switching power supply
time2006/09/18
- Switching power supply has anti-interference performance. Due to its own circuit structure (multi-stage series), general input interference such as surge voltage is difficult to pass. Compared with linear power supply, the output voltage stability is compared with the linear power supply. Big advantage.
Switching power supply has anti-interference performance. Due to its own circuit structure (multi-stage series), general input interference such as surge voltage is difficult to pass. Compared with linear power supply, the output voltage stability is compared with the linear power supply. The larger advantage is that the output voltage stability can reach (0.5~1)%. As a power electronic integrated device, the switching power supply module should pay attention to the following three points in the selection:
1, the choice of output current
Because the switching power supply has high working efficiency, it can generally reach more than 80%. Therefore, in the selection of its output current, the large absorption current of the electrical equipment should be accurately measured or calculated, so that the selected switching power supply has a high performance-price ratio. Usually the output calculation formula is:
Is=KIf
Where: Is—the rated output current of the switching power supply; If—the large absorption current of the electrical equipment; K—the margin factor, generally taking 1.5 to 1.8;
2, ground
Switching power supply will generate more interference than linear power supply. Grounding and shielding measures should be taken for electrical equipment sensitive to common mode interference. According to EMC limits such as ICE1000, EN61000, FCC, etc., switching power supply adopts EMC electromagnetic compatibility measures, so the switch The power supply should normally have an EMC EMC filter. Such as the joint transmission power supply, the FG terminal is connected to the earth or the user's casing to meet the above requirements of electromagnetic compatibility.
3, the protection circuit
The switching power supply must have overcurrent, overheat, short circuit and other protection functions in the design. Therefore, the switching power supply module with complete protection function should be preferred in design, and the technical parameters of the protection circuit should match the working characteristics of the electrical equipment. Avoid damage to electrical equipment or switching power supplies.