Precautions for module power application

1. Extremely light load

Generally, the module power supply has a minimum load limit, which varies from manufacturer to manufacturer, and is generally about 10%. When the load is too light, the energy storage element will have difficulty in freewheeling and current discontinuity will occur, resulting in unstable output voltage. This is determined by the working principle of the power supply itself. But what if the user does use it with light load or no load? The most convenient and effective way is to add a certain dummy load, which is about 2% of the output power. It can be preset by the module manufacturer before leaving the factory, or the user can install an appropriate resistor outside the module as the load. It is worth noting that if the former is selected, the module efficiency will be reduced. But some circuit topologies have no minimum load limit.

2. Multiple output power distribution

When selecting the power supply of multi-channel output module, pay attention to the power distribution between different outputs. Take two-way products as an example, there are generally two types: one is two-way balanced load, that is, the two-way current is the same; The other is unbalanced load, that is, the load currents of the main and auxiliary circuits are different, the main circuit is large and the auxiliary circuit is small. For this product, it is recommended that the ratio of the power of the auxiliary circuit to the power of the main circuit be 1 / 5 ~ 1 / 2. Within this range, the voltage stability of the auxiliary circuit can be guaranteed (within 5%). Otherwise, the voltage of the auxiliary circuit will be too high or too low. On the other hand, if the two-way loads are not the same, try not to choose the balanced load module power supply, because this power supply is specially designed for symmetrical loads. If the load is unbalanced, the auxiliary voltage accuracy is not high

3. Try to reduce the temperature rise of module power supply

The working temperature of the internal components of the module directly affects the service life of the module power supply. The lower the component temperature, the longer the module service life. Under certain working conditions, the loss of the module power supply is certain, but the temperature rise can be reduced by improving the heat dissipation conditions of the module power supply, so as to greatly extend its service life. For example, a module power supply of more than 50W must be installed with a radiator. The larger the surface area of the radiator, the more conducive to heat dissipation. The installation direction of the radiator should be as conducive to the natural convection of air as possible. For a power of more than 150W, a fan can be installed for forced air cooling in addition to the radiator. In addition, in places with high ambient temperature or poor air circulation conditions, the module must be derated to reduce power consumption so as to reduce temperature rise and prolong service life.

4. Reasonable installation to reduce mechanical stress

The module power supply is led out by metal pins, and the module power supply and external circuits, metal pins and internal circuits of the module power supply are connected by welding. In some special occasions, the mechanical vibration intensity is high, especially when a radiator is added to the power supply of the high-power module, which is even more serious. Although thermal conductive insulating rubber is generally encapsulated inside the module power supply to provide better cushioning and protection for the components, the solder joints may break due to the failure of the module power supply due to the failure of the module power supply. At this time, additional fixing and cushioning measures must be taken on the basis of welding, such as connecting the module with the chassis, chassis and the power supply with clamps or bolts (for modules with screw holes) Large circuit boards and other components with good anti vibration performance are fixed, and some elastic materials are placed between them to cushion the stress generated by vibration.