Language : Chinese
There is a certain amount of loss when any equipment is working, and most of the loss becomes heat. Low power consumption equipment has low loss and does not require a radiator. However, the loss of high-power equipment is huge. If heat dissipation measures are not taken, the temperature of the chip will reach or exceed the allowable junction temperature, and the device will be damaged. Therefore, it is necessary to add a heat sink. It is very common to install power devices on a radiator and use the radiator to dissipate heat to the surrounding space. If necessary, add a cooling fan to enhance heat dissipation and cooling under a certain wind speed. The flowing cold water cooling plate is also used in the power unit of some large equipment, and the heat dissipation effect is better. Heat dissipation calculation is to determine suitable heat dissipation measures and heat sinks through calculations under certain working conditions. The power unit is installed on the radiator. Its main heat flow direction is from the die to the bottom of the device, and the heat is dissipated to the surrounding space through the heat sink.
The small electronic radiator (or radiator) is made of aluminum alloy sheet by stamping process and surface treatment, and the large electronic radiator is made of aluminum alloy extruded profile, and then mechanical processing and surface treatment. They come in various shapes and sizes, and are suitable for different equipment installations and equipment with different power consumption. The radiator is generally a standard part, and profiles can also be provided, which can be cut into a certain length by the user according to the requirements to make a non-standard radiator. The surface treatment of the radiator is electrophoretic coating or black oxygen polarization treatment, the purpose is to improve the heat dissipation efficiency and insulation performance. Natural cooling can increase by 10.15%, ventilation cooling can increase by 3%, electrophoretic paint can withstand 500800V.
Electronic radiator manufacturers provide thermal resistance values or related curves for different types of radiators, and different thermal resistance values under different heat dissipation conditions.
Calculation: The low-frequency power amplifier adopts the power operational amplifier PA02. The device is packaged in an 8-pin TO-3 metal case. The working conditions of the device are: the working voltage VS is 18V, the load impedance RL is 4, the working frequency can reach 5Hz under DC conditions, the ambient temperature is set to 40°C, and natural cooling is adopted. According to the data of PA02 device, the typical value of quiescent current IQ is 27mA, and the extreme value is 40mA. The typical value of RJC (from mold to case) of the device is 2.4°C/W, and the extreme value is 2.6°C/W.