Seven points for attention in the selection of power modules

01

rated power

Theoretically speaking, when selecting a module, the higher the power, the better, so as to ensure the operation of the system with higher requirements. But the greater the power, the larger the volume, and the cost will increase significantly. Therefore, when choosing a power module for design, it is best to choose a product whose working power is maintained at 30-80% of the power module used, because for general modules, within this power range, the performance of the module power supply is relatively good. Stable and reliable, more conducive to the long-term operation of the module. If you choose a product with too large power, it will cause waste; if you choose a power that is just right or too small, it will easily cause the load to be too heavy. Although there are currently some power module products that can be overloaded, they can only be used for emergency use, and long-term use in this way is not recommended. Of course, this depends on different products and different requirements. You can choose the most appropriate power module according to your own product characteristics and needs.

02

Package form

There are various packaging forms of power modules. Some commonly used products meet international standards, and many are non-standard products. Moreover, the products of the same company will have different packaging forms for the same power; on the contrary, the same packaging will also have different powers. This can be reasonably selected according to the requirements of your own products. Generally consider three points:

PART.

01

Under the premise of determining the power and meeting the heat dissipation requirements of the product, the package size should be as small as possible, which is more conducive to the volume control of the product and can also leave space for more important components. Of course, if the size is not very important, in order to make the product more weighty, you can also choose a larger size, and you can also get a better heat dissipation effect.

PART.02

Try to use international standard products. Because these products have undergone a lot of use and verification, they are relatively mature products, thereby reducing the risk of product development. And later, for some reasons, it is easier to replace products of the same standard with other brands.

PART.03

It is best to have scalability to facilitate later expansion and upgrades. For example, for the same package, due to product upgrades in the later period, it can be replaced with a higher power one, but the size and package remain unchanged, so that product upgrades can be completed quickly.

So it can be seen that the packaging form is also considered according to your own needs. Especially for some products with their own characteristics, manufacturers can be required to carry out independent development to meet the requirements of their own products, and it can also prevent others from copying their products to a certain extent and protect their own products. Then keep improving in use to make power supply products better and better. Taking the power module products of Aipu Electronics as an example, the product series cover international standard, non-standard, user-customized and other packaging forms. The product work is also quite stable and can meet the different needs of users.

03

temperature range, working environment

At present, the classification of power modules is mainly commercial grade, industrial grade, and military grade. Different grades have requirements for the environment, such as operating temperature, vibration, humidity, and dust. Therefore, when choosing a module product, it is necessary to fully consider the environment in which the product is located. If it is not selected properly, it will affect the use. For this requirement, users should take it seriously. If there is any special requirement, please ask the technical engineer of Aipu to avoid affecting the work process. There are two selection methods: 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 the condition of a certain volume (package form), then the nominal temperature range of the module must strictly meet the actual needs or even There is a slight margin. The second is to choose according to the temperature range. If you choose a product with a smaller temperature range due to cost considerations, but sometimes the temperature approaches the limit, what should you do? Derating use. That is to choose a product with a larger power or package, so that the "big horse-drawn car" has a lower temperature rise, which can alleviate this contradiction to a certain extent. The derating ratio varies with different power levels, generally 3~10W/℃ for above 50W. In short, either choose a product with a wide temperature range, which has better 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 the power margin and package form must be larger. A compromise should be considered.

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

04Working frequency

Generally speaking, the higher the operating frequency, the smaller the output ripple noise, and the better the dynamic response of the power supply. However, 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, it is necessary to choose a product with a higher switching frequency for high-demand applications.

05 Isolation voltage

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

06 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 failure disappears. The protection function of the module power supply should at least include input overvoltage, undervoltage, soft start protection; output overvoltage, overcurrent, short circuit protection, high-power products should also have overtemperature protection, etc.

Wide input voltage 2:1 (highest: lowest) Conversion efficiency typically 84% Wide operating temperature range: -40~85°C Flame retardant meets UL94-V0 requirements (only for plastic cases) Input and output isolation voltage: 1500Vdc Output short circuit, over Current protection (automatic recovery) Copper shell (E7) / plastic shell (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 Product warranty for 5 years Any output voltage between 3.3-48VDC can be produced.

07 Power Consumption and Efficiency

Under a certain output power condition, the smaller the module loss P is, the higher the efficiency is, the lower the temperature rise is, and the longer the service life is. In addition to the normal loss at full load, there are two 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 are, the higher the efficiency of the module is, especially if the short-circuit is not taken in time In the case of measures, it may last for a long time, and the smaller the short-circuit loss is, the probability of failure is also greatly reduced. Of course, the smaller the loss, the more in line with the requirements of energy saving.