1. Consider the output power of the product: 1----60W. It is generally recommended that the actual power used is 30 to 80% of the rated power of the module power supply (the specific proportion is also related to other factors, which will be mentioned later). Within this power range, the performance of the module power supply in all aspects is relatively full and stable reliable. Too light a load causes waste of resources, and too heavy a load is detrimental to temperature rise and reliability. All module power supplies have a certain overload capacity,

2. How much V is the input voltage and how much V is the output voltage; whether the output voltage is single output or dual output.

3. Is there any requirement for isolation voltage? In general, the isolation voltage of the module power supply is not very high, but the higher isolation voltage can ensure that the module power supply has less leakage current, higher safety and reliability, and better EMC characteristics. Therefore, the current industry The general isolation voltage level is above 1500VDC.

4. Working temperature and derating use: -40-85 degrees, -25-75 degrees. Generally, the module power supply of the manufacturer has several temperature range products to choose from: commercial grade, industrial grade, military grade, etc., when choosing the module power supply, the actual working temperature range must be considered, because the temperature grade is different and the manufacturing process is different The price varies greatly, and improper selection will also affect the use, so it has to be carefully considered. There are two ways to choose: one is to choose according to the power used and the package form. If the actual power used is close to the rated power under a certain volume (package form), then the nominal temperature range of the module must strictly meet the actual needs or even Slight margin. The second is to choose according to the temperature range. If the product with a smaller temperature range is selected due to cost considerations, but sometimes the temperature is approaching the limit, what should I do? Use derating. That is, choose products with higher power or packaging, so that the temperature rise of the "large horse-drawn carriage" is lower, which can alleviate this contradiction to a certain extent. The derating ratio varies with the power level, generally 3～10W/℃ above 50W. In short, either choose a product with a wide temperature range, the power utilization is more adequate, and the package is smaller, but the price is higher; or choose a general temperature range product, the price is lower, the power margin and the package form must be larger. Should be compromised.

5. Are there any requirements for packaging and size? There are many different types of packaging for the module power supply. There are also international standards and non-standard ones. For the same company products, the same power products have different packages, and the same package has different power, then How to choose the packaging form? There are three main aspects: ① The volume should be as small as possible under certain power conditions, so as to give more space and function to other parts of the system; ② Try to choose products that comply with international standard packaging, because the compatibility is better, not limited to one or two Supplier; ③ It should be expandable to facilitate system expansion and upgrade. Choose a package, because the system requires higher power for functional upgrades, the power module package remains unchanged, and the system circuit board design does not need to be changed, which greatly simplifies product upgrades and upgrades and saves time. Full brick; 116.8*61*12.7mm half brick: 61*57.9*12.7mm quarter brick: 57.9*36.8*8.1mm quarter brick: 57.9*22.9*10.4mm. The working environment of brick DC/DC converters is getting worse and worse. Although these module products have not much room for development as a general product, suppliers are still making further efforts to fully tap the potential of these devices. At present, the market's requirements for improving power density and efficiency are mainly concentrated on small converters, and newly released products are rarely converters over half a brick size. Of course, reducing the size to the smallest is not the most urgent requirement. In fact, the current mainstream of the market is mainly one-eighth brick products. From a technical perspective, compatibility with wide and narrow input, modulated and unmodulated output, wireless applications, and power over Ethernet (PoE) applications has become a hot topic.

6. Fault protection function. Relevant statistical data show that the main reason for the failure of the module power supply within the expected effective time is the damage under external fault conditions. The probability of failure in normal use is very low. Therefore, an important part of extending the life of the module power supply and improving the reliability of the system is to select products with perfect protection functions, that is, the module power supply can automatically enter the protection state without permanent failure when the external circuit of the module power supply fails, and should be able to Automatically return to normal. The protection function of the module power supply should include at least input overvoltage, undervoltage, soft start protection; output overvoltage, overcurrent, short circuit protection, and high-power products should also have overtemperature protection.

7. Power consumption and efficiency. According to the formula, Pin, Pout, P consumption are the module power input, output power and its own power loss. It can be seen from this that under certain conditions of output power, the smaller the loss P of the module, the higher the efficiency, the lower the temperature rise, and the longer the life. In addition to the normal loss at full load, there are two other losses worth noting: no-load loss and short-circuit loss (module power loss when the output is short-circuited), because the smaller these two losses, the higher the module efficiency, especially if the short-circuit is not taken in time In the case of measures, it may last longer, and the smaller the short-circuit loss, the probability of failure is greatly reduced. Of course, the smaller the loss, the more energy-saving it is.

8. Working frequency. Generally speaking, the higher the operating frequency, the lower the output ripple noise and the better the dynamic response of the power supply. However, the higher the requirements for the components, especially the magnetic materials, the higher the cost. Therefore, the switching frequency of domestic module power products is more In order to be below 300kHz, or even only about 100kHz, it is difficult to meet the requirements of dynamic response under load varying conditions. Therefore, high-frequency applications should be considered for applications with high requirements. On the other hand, when the module power switching frequency is close to the signal operating frequency, it is easy to cause beat oscillation, and this point should also be considered when selecting.

In short, module power supply and other components can only be maximized in performance and reliability when fully selected and applied reasonably, and module power supply will be more widely adopted!