Touch the surface of the power module, it is warm, the module is broken? Wait a minute, it's a little hot, just because it's working hard. However, high temperature has a great impact on the reliability of the power module! serial rs485 to ethernet converter Based on the knowledge of the thermal design of the power module, this time, we will take a look at the reasons for the heating of the power module.
The power module has energy loss during the voltage conversion process, and the heat generated will cause the module to heat up, reduce the conversion efficiency of the power supply, affect the normal operation of the power module, and may affect the performance of other surrounding devices. This situation needs to be checked immediately. But under what circumstances will the power module overheat? The specific reasons are as follows:
1. Using a linear power supply module
The working principle of the linear power supply is shown in Figure 1, and the output voltage can be changed by adjusting the regulator tube RW. Since the adjustment tube is equivalent to a resistor, it will generate heat when the current passes through the resistor, resulting in low efficiency.
Figure 1 Schematic diagram of linear power supply
Figure 1 Schematic diagram of linear power supply
In order to prevent the power module from overheating, the following measures can be taken: increase the heat sink, implement air cooling, solve heat-conducting materials (thermal silicone grease, heat-conducting potting glue), and switch to switching power supply.
2. Load overcurrent
The power supply overload is just the opposite of the light load of the power supply, that is, there is a short circuit in the load circuit of the power supply circuit, which makes the power supply circuit output a large current, which exceeds the range that the power supply can withstand.
For a power module without over-current protection, the easiest way to output voltage regulation, over-voltage and over-current protection is to connect an external linear regulator with over-current protection to the input, as shown in Figure 3.
Figure 2 Load overcurrent, add a linear regulator
Figure 2 Load overcurrent, Lorawan Node Outdoor Gateway add a linear regulator
3. The load is too small
The power supply is lightly loaded, that is, the load impedance of the power supply circuit is relatively large, and the output current of the power supply to the load is relatively small at this time. Some power circuits do not allow the light load of the power supply, otherwise the DC working voltage output by the power circuit will increase a lot, causing damage to the power circuit. Generally, power modules have a minimum load limit, which varies from manufacturer to manufacturer, but is generally around 10%.
If the output load is too light, it is recommended to connect a preload resistor in parallel with the output, as shown in Figure 2. The sum of the preload resistance power plus the actual load power is >10% load.
4. The ambient temperature is too high or the heat dissipation is poor
Before using the module power supply, be sure to consider the temperature grade of the power module and the actual required operating temperature range. Perform derating design according to load power and actual ambient temperature.