A suitable switching power supply can not only improve the cost performance of electronic equipment, but also determine the reliability and product characteristics of electronic equipment,

Here are some tips and precautions for selecting switching power supply:

1. Differentiation between constant voltage power supply and constant current power supply:

Constant voltage means that the output voltage is constant. When used within the rated power, the ideal constant voltage output power supply load current changes, and the output voltage remains constant,

The current is between zero and the rated maximum output current according to the power consumption at the load end;

Constant current means that the output current is constant. When it is used within the rated power, when the terminal voltage characteristics of the load change, the constant current output power supply ensures constant current,

The output voltage will change with the load, while the output current will remain constant;

When an output voltage on the product label is a fixed value, the output belongs to constant voltage output; when the output voltage on the product label is a range, the output belongs to constant current output.

2. Purpose of constant voltage power supply and constant current power supply

The constant voltage power supply is applicable to the load whose internal resistance characteristics will change during use. For the LED stage lamp, the constant voltage output power supply is generally connected to the control board with built-in constant current circuit, which mainly supplies power for the single-chip microcomputer power supply circuit, motor drive circuit, cooling fan power supply, LED constant current drive circuit, and other auxiliary circuits on the control board. The constant voltage output power supply cannot directly drive the LED lamp beads, otherwise the LED lamp beads will not be loaded or burned;

The constant current power supply is applicable to the load whose terminal voltage characteristics will change during use. The LED lamp beads belong to this kind of load. Although its terminal voltage is a fixed value at normal temperature, its terminal voltage will change after power-on and use because of the temperature rise. For the LED stage lamps that need to be directly driven by the power supply at present, the constant current output power supply must be used to provide a constant working current for the LED, To ensure the brightness, power consumption stability and service life after working temperature rise.

3. Selection description of power specification

Most of the parameter data of our power supply are tested based on Vin=220Vac at room temperature of 25 ℃. The actual customer application conditions are different. For the power supply, the working environment temperature is very critical, and temperature is one of the key factors determining the maximum usable power;

Several factors that can lead to high power supply temperature: low 100-120VAC input voltage, high ambient temperature, close to the heat source, poor air mobility near the power supply, and low voltage and high current power supply output;

Without accurate measurement of current and power and evaluation of the power supply selected under heat dissipation conditions, it is not ruled out that the power supply will work in the limit state, overload or slight overload state, and there may be no problems if it is used for a short time,

Because the power overload protection point is generally set in the range of 110% - 150% of the rated power. The temperature rise of the power supply working in the extreme or even overload state is relatively high, which will affect its reliability and service life. Therefore

When selecting the power supply, customers should focus on the heat dissipation effect of the power supply environment, and the maximum power should be measured and calculated. Our company can also provide measurement and evaluation services for customers;

When the heat dissipation effect of the power supply is not ideal and the power margin is insufficient, the power supply must be derated (refer to the characteristic curve in the product specification provided by our company),

Or select a higher power supply. The following selection principles shall be referred to when recommending customers to select power supply:

(1) When the heat dissipation condition is good or the ambient temperature is not high, and the input voltage is 200-240Vac, 20% of the rated power margin is reserved for the power supply;

(2) When the heat dissipation condition is good or the ambient temperature is not high, and the input voltage=100-120Vac or the full voltage range, 30% of the rated power margin is reserved for the power supply;

(3) When the heat dissipation condition is poor or the ambient temperature is high, and the input voltage is 200-240Vac, select the power supply to reserve 30% of the rated power margin;

(4) When the heat dissipation condition is poor or the ambient temperature is high, and the input voltage is 100-120Vac or the full voltage range, 40% of the rated power margin is reserved for the power supply.

4. Impact of cross adjustment rate

When selecting multiple groups of output power supply, the mutual influence of alternating fluctuation of each group of load current on the output voltage of power supply shall be considered. Multiple groups of output power supply are divided into main output and auxiliary output, and the auxiliary output is easy to be affected by the main output belt

If the voltage increases or decreases due to the load size, the customer should consider the voltage acceptance range of the secondary output load or ensure that each group carries at least 10% of the constant load. If the load still cannot be met

In case of demand within the fluctuation range, customers are required to provide finished products or electrical loads. Our company can customize power supply that meets the demand parameters for customers.

5. Installation and wiring of power supply

When installing bare plate power supply in metal case, the height of power supply support stud shall not be less than 6mm in consideration of the reliable distance of safety regulations. When certification is required, insulating sheet can be added between the bottom of power supply and case;

When installing the power supply with a housing, the length of the screw for locking the power supply should be controlled to ensure that the screw does not puncture the insulating sheet between the power PCB board and the power supply housing after the screw is locked,

There is a gap of more than 2mm between the solder joint and the bottom of the power circuit board;

50. N refers to the zero line, live line and FG refers to the grounding port at the AC input terminal. In case of single group output, V+and V - respectively represent the output positive and negative poles. In case of multiple groups of output,

V1, V2, V3... respectively represent the positive pole of each output group, and G represents the common negative pole of each output group.