Switching power supply use must know precautions!

Switching power supply is now a very common equipment supporting products in the home, but most people do not know much about it. Today let's take a look at the switching power supply use must know matters needing attention!

First, output calculation

Because the switching power supply work efficiency is high, generally can reach more than 80%, so in its output current selection, should accurately measure or calculate the maximum absorption current of electrical equipment, so that the selected switching power supply has a high performance-price ratio, usually 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;

Two, grounding

Switching power supplies produce more interference than linear power supplies. For electrical equipment sensitive to common-mode interference, grounding and shielding measures should be taken. According to EMC restrictions such as ICE1000, EN61000 and FCC, switching power supplies should adopt EMC EMC measures. For example, Leadworth technology's HA series switching power supply, the FG terminal can be connected to the ground or the user's housing to meet the above requirements of electromagnetic compatibility.

Three, protect the circuit

Switching power supply in the design must have overcurrent, overheating, short circuit and other protection functions, so in the design should be the first choice of the switching power module with complete protection functions, and the technical parameters of the protection circuit should match the working characteristics of the electrical equipment, to avoid damage to the electrical equipment or switching power supply.

Four, wiring method

L: connected with 220v AC live wire;

N: connected with 220v AC neutral line;

FG: ground;

G: DC output ground;

+5v: port for the output +5V point;

ADJ: It is to adjust the output voltage in a certain range. The rated voltage of the output on the switching power supply is fixed when leaving the factory, that is, the nominal rated output voltage. Setting this potentiometer can allow users to adjust the output voltage in a smaller range according to the actual use situation.

Five, switching power supply use precautions

1, the input voltage of the switching power supply can be 220V or 110V, according to the circuit design reasonable choice of input voltage gear. Otherwise, it will cause damage to the switching power supply.

2. Pay attention to distinguish the ground terminal and the neutral terminal of the output voltage terminal of the switching power supply. And ensure reliable grounding of switching power supply.

3. The metal shell of the switching power supply is generally connected to the ground (FG), and should be grounded reliably to ensure safety. Do not mistakenly connect the shell to the neutral line;

4, before the installation of the switching power supply is completed and energized for trial, please check and proofread the connection on each terminal again, make sure that input and output, AC and DC, single phase and polyphase, positive and negative, voltage and current value, etc., are correct before power operation;

5, for high-power switching power supply, generally have two or more than two "+" output terminal "-" output terminal, in fact, they belong to an output electrode, just to facilitate the user connection, and multiple terminals are respectively in the internal and connected together;

6, in order to achieve full heat dissipation, the general switching power supply should be installed in a position with good air convection conditions, or installed on the case shell through the shell to transfer the heat out;

7, switching power supply before factory resistive load test, if it needs to be used in capacitive or inductive load, should be explained in advance in the order contract;

8, for the dual switching power supply output symmetric load, the priority is to use symmetrical output power supply;

9. For grounding users of switching power supply FG, it is normal to feel numb electricity when touching the shell or the output. When floating to the ground, FG has about 110V AC output to the ground, which is determined by the internal structure of the power supply.

10, the switching power supply before leaving the factory 100% filled negative in aging, generally control the power utilization rate within 80% or lower, can greatly improve the service life of the power supply, generally every increase in the power supply temperature 10℃ capacitor life is reduced by half;

11. The ripple and noise of switching power supply are AC components superimposed on the DC output voltage, generally expressed by millivolt peak;

12. For all switching power supplies, when the load is sudden, there will be a certain response time. During this sudden change, the output voltage of the power supply will have a short overshoot process at an instant, and then return to the normal output state, which is the dynamic response;

13. Once the switching power supply fails, the factory should be notified in the fastest way. The factory will be responsible for free maintenance or technical guidance, except for those who disassembly the power supply.

For the use of switching power supply must know the precautions introduced here, hope to help you use the correct switching power supply!