What should be paid attention to when choosing a power supply module

The power supply module customization is a power supply that can be directly mounted on the printed circuit board. Its characteristics are that it can be an application-specific integrated circuit (ASIC), digital signal processor (DSP), microprocessor, memory, field programmable gate array ( FPGA) and other digital or analog loads provide power. So what should be paid attention to when choosing a power module customization?

1. Rated power

Theoretically speaking, when selecting a module, the greater the power, the better, so that the system can run with higher requirements. But the greater the power, the larger the volume, and the cost will also increase substantially. Therefore, when designing to customize the power supply module, it is best to choose the working power of the product to maintain 30-80% of the customized power supply module used, because for general modules, within this power range, the performance of the module power supply is exerted. Both are relatively stable and reliable, and are more conducive to the long-term operation of the module. Choosing a power product that is too large will cause waste; choosing a power that is just right or too small will easily cause the load to be too heavy, the system will be unstable in the lighter, and the components will be burned in the heavy. Although there are currently some customized power module products that can be overloaded, they can only be used for emergency purposes, and long-term use is not recommended. Of course, this depends on different products and different requirements. You can choose the most appropriate power module to customize according to your own product characteristics and needs.

2. Package form

There are a variety of custom packaging forms for power modules. Some of the commonly used products conform to international standards, and many are non-standard products. And the products of the same company, the same power will have different packaging forms; on the contrary, the same package will also have different powers, this can be based on the requirements of your own products, a reasonable choice of packaging. Generally consider three points: 1. On the premise of determining the power, the package size should be as small as possible to meet the heat dissipation requirements of the product, which is more conducive to the volume control of the product and can also leave space for more important components. Of course, if the volume is not very important, in order to make the product more weight, you can also choose a larger size to get a better heat dissipation effect. 2. Try to choose products of international standards. Because these products have undergone a lot of use and verification, they are relatively mature products, thereby reducing the risk of product development. And for some reasons later, it is easier to change other brands of the same standard products. 3. It is best to have scalability to facilitate later expansion and upgrades. For example, in the same package, due to product upgrades in the later stage, it can be replaced with a larger power but the size and package remain unchanged, so that the product upgrade can be completed quickly. Therefore, it can be seen that the packaging form is also considered according to their own needs. Especially for products with their own characteristics, manufacturers can be required to develop independently to meet their own product requirements, and to a certain extent, it can also prevent others from plagiarizing products and protect their products. Then continue to improve in use to make power products better and better.

3. Temperature range and working environment

At present, the customized classification of power modules is mainly commercial grade, industrial grade and military grade. Different grades have requirements on the environment, such as operating temperature, vibration, humidity, and dust. Therefore, when choosing a module product, we must fully consider the environment in which the product is located. If the choice is not appropriate, it will affect the use. Users should take this requirement seriously, and if there are special requirements, they should ask the engineer clearly so as not to affect the work process. There are two options: one is to choose according to the use power and package form. If the actual use power 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 a 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 a product with a larger power or package, so that the temperature rise of the&"big horse-drawn trolley GG" will be lower, which can alleviate this contradiction to a certain extent. The derating ratio varies with different power levels, generally 3~10W/℃ above 50W. In short, either choose a product with a wide temperature range, which has more full power utilization and a smaller package, but the price is higher; or choose a product with a general temperature range, which has a lower price, and a larger power margin and package form. A compromise should be considered.

For other special requirements, you can contact an engineer to confirm the use environment of your product.

Four, working frequency

Generally speaking, the higher the operating frequency, the smaller the output ripple noise and the better the dynamic response of the power supply. But the requirements for components, especially magnetic materials, are also higher. Generally, the switching frequency of the module power supply is below 300kHz, or even lower. Therefore, high-demand occasions need to choose higher switching frequency products.

Five, isolation voltage

In general occasions, the isolation voltage requirements of the module power supply are not very high, but higher isolation voltage can ensure that the module power supply has smaller leakage current, higher safety and reliability, and better EMC characteristics. Therefore, the current industry The general isolation voltage level is above 1500VDC.

Six, fault protection function

That is, when the external circuit of the module power supply fails, the module power supply can automatically enter the protection state without permanent failure, and it should automatically return to normal after the external fault disappears. The protection functions of the module power supply should include at least input overvoltage, undervoltage, and soft-start protection; output overvoltage, overcurrent, and short circuit protection, and high-power products should also have over-temperature protection.

Wide input voltage 2:1 (Highest: Lowest) Conversion efficiency typical 84% Wide operating temperature range: -40~85℃ Flame retardant meets UL94-V0 requirements (only for plastic case) Input and output isolation voltage: 1500Vdc Output short circuit, over Current protection (automatic recovery) Copper case (E7)/Plastic case (E2) Output voltage accuracy: main circuit ±1%, auxiliary circuit ±3% Ripple and noise (20MHz, nominal input voltage): Vo≤5.0V, ≤ 50mVp-p; Vo≥48V, ≤180mVp-p; Other, ≤100mVp-p The product warranty is 5 years and the output voltage can be produced at any voltage between 3.3-48VDC.

Seven, power consumption and efficiency

Under certain conditions of output power, the smaller the module loss P, the higher the efficiency, the lower the temperature rise, and the longer the service 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 efficiency of the module, especially if the short-circuit is not taken in time. In the case of measures, it may last for a longer time, and the smaller the short-circuit loss, the greater the probability of failure. Of course, the smaller the loss, the more it meets the requirements of energy saving.