DC直流隔離磚的熱工性能

　　電源技術(shù)的改進，特別是MOSFET開關(guān)的效率，使供應商能夠提高DC / DC隔離轉(zhuǎn)換器磚功率模塊（“磚”）的“功率密度”（功率/體積）。早期的全磚可以提供50瓦，但快速的改進使得半磚設計很快就能滿足這一要求。今天，1/8磚可以產(chǎn)生超過200瓦，甚至1/16磚可以拿出100 W，這意味著設計師可以安裝一個較小的磚與前一代的大型設備相同的功率輸出，節(jié)省印刷電路板（PCB）的房地產(chǎn)。

　　然而，許多工程師直覺地認為，使用一個1/16磚，例如，與舊的，更大的設備相同的功率輸出意味著它將運行更熱。然而，這并不一定總是如此；較小的設備受益于物理屬性，它們實際上可以使它們運行在與可比較大的轉(zhuǎn)換器相同的溫度下，甚至稍微冷卻。本文將仔細研究這些緊湊型電源。

　　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.