DC直流隔离砖的热工性能

　　DC直流隔离砖的热工性能

　　电源技术的改进，特别是MOSFET开关的效率，使供应商能够提高DC / DC隔离转换器砖功率模块（“砖”）的“功率密度”（功率/体积）。早期的全砖可以提供50瓦，但快速的改进使得半砖设计很快就能满足这一要求。今天，1/8砖可以产生超过200瓦，甚至1/16砖可以拿出100 W，这意味着设计师可以安装一个较小的砖与前一代的大型设备相同的功率输出，节省印刷电路板（PCB）的房地产。

　　然而，许多工程师直觉地认为，使用一个1/16砖，例如，与旧的，更大的设备相同的功率输出意味着它将运行更热。然而，这并不一定总是如此；较小的设备受益于物理属性，它们实际上可以使它们运行在与可比较大的转换器相同的温度下，甚至稍微冷却。本文将仔细研究这些紧凑型电源。

　　Locating the hot spot

　　A DC/DC isolated converter in a fractional brick format is a self-contained， power supply module suitable for on-board use. The brick typically comprises all the components （apart from filter circuits） required for a switching power supply including MOSFET switches， energy storage components， and switching controller. （See the TechZone article “An Introduction to Board-Mounted DC/DC Converter Bricks.”）

　　By selecting a fractional brick， an engineer does not have to worry about the intricacies of switching power supply design. The supplier has done all the work to ensure the unit operates optimally. However， because these devices boast power densities that can exceed 7 W/cm³， they tend to generate a lot of heat. Managing that heat is one of the toughest challenges for the designer.

　　While a 1/16 bridge converter is delivered in a modular format， it does comprise several components， each of which dissipate different amounts of power. Figure 1 shows a 36 to 75 V input， 12 V output， 30 W 1/16 brick from Murata’s ULS Series. Note the variety of components on the module’s topside.