理解高效MCU设计的功耗和性能权衡

　　理解高效MCU设计的功耗和性能权衡

　　单片机作为主控单元，在每一个可以想象的应用。它们的力量和灵活性使它们成为大多数设计的核心部件。使用MCU往往依赖于智能权衡功耗和性能之间建立高效的设计的关键。许多微控制器提供供电的单片机，单片机的时钟速率，从而限制了几个选项，其性能。了解工作电压和工作时钟频率之间的共同关系可能是至关重要的，以获得您的下一个MCU设计最。

　　本文将回顾一些驱动MCU通用选项和讨论造成的限制，可能会导致性能。在运行时修改的工作电压，以获得最佳的性能和功率效率的最佳组合的共同技术将探讨，以帮助您选择和实施您的下一个基于MCU的设计。

　　Frequency vs. operating voltage – a key performance consideration

　　One of the most fundamental relationships between performance and power is the voltage at which the MCU operates. Operating power is directly related to operating voltage （by definition since power equals voltage times current）， so clearly the operating power needs to be a key consideration when deciding on the MCU you will use for your design. You might think that this means you should always use the lowest power MCU， but if performance is at all an issue in your design you will need to consider the operating frequency as a key element as well， and an MCU’s operating frequency is often limited by its operating voltage.

　　Many MCU manufacturers understand the importance of the relationship between operating voltage， frequency of operation， MCU performance， and MCU operating power and they provide different levels of operating power and operating frequency to make it easier to optimize the design for a best fit to your system requirements. As an example， the Renesas RL78 MCU has four different operating voltage ranges， each supporting a different operating frequency， as illustrated in Figure 1 below. Between 1.6 V and 1.8 V， the RL78 can run anywhere between 1 MHz and 4 MHz. Between 2.7 V and 5.5 V， it can run at a maximum of 20 MHz. Thus， the RL78 can operate five times faster if it uses 2.7 V instead of 1.8 V， only a 50% increase in the operating voltage.