积极寻求更好的ORing解决方案

　　积极寻求更好的ORing解决方案

　　有源ORing提供显著的好处在肖特基二极管的MOSFET，但它强加一些设计参数，工程师需要了解为了开发出最合适的解决方案

　　利用二极管主动组合多个或冗余电源是一项跨越半导体工业历史的技术，因为二极管是当今使用的最简单和最有用的半导体之一。然而，由于正向偏置pn结的“撬棍”效应，它的简单性也在这一类应用中失败了。虽然现在有一系列不同的开关特性，选择二极管，如功率肖特基二极管，基本功能是“开”或“关”，与一个半导体结的主要好处：控制。由于二极管pn结的基本物理特性，它们通过的电流越多，耗散的功率就越大。

　　用较先进的场效应晶体管取代不起眼的二极管降低了功耗，并引入了二极管无法控制的水平，但也有其后果。了解这些后果使半导体产业发展的一系列控制解决方案的拓扑结构采用有源ORing MOSFET。

　　Active ORing is now commonplace in power supply design， but is most relevant in applications that must match the needs of delivering significant levels of power with a high degree of ruggedness and reliability. Today， that typically points towards telecommunications， but it is equally valid in other applications where load sharing/balancing between power supplies is implemented， or where so-called ‘N+1’ redundancy is required.

　　Conceptually， replacing diodes with MOSFETs is relatively straightforward and brings instant benefits in terms of reliability. The power dissipated by a diode when it is conducting is significant and proportional to the current passing through it， so in high power applications， the diodes tend to dissipate higher power. In turn， this demands the use of larger diodes and heat sinks， or other cooling solutions such as forced air or convection. Wherever cooling becomes necessary， it represents a potential point of failure. So， as the heat dissipated by diodes increases， so too does the risk of failure. It is widely accepted that despite the efforts to lower the active power consumption of integrated devices， the power demand trend of today‘s applications is only increasing， thereby demanding ever more powerful power supplies and， in turn， larger diodes with their associated heat dissipation issues.