優(yōu)化低功耗嵌入式設(shè)計(jì)

　　無(wú)論你的嵌入式設(shè)計(jì)是否能擺脫電池或墻壁電源，它需要從一開(kāi)始就對(duì)能源效率進(jìn)行優(yōu)化。本文討論了在選擇微控制器時(shí)需要考慮的許多問(wèn)題，包括其功率配置、各種操作模式中的可用控制功能和外圍設(shè)備的功耗。

　　對(duì)低功耗嵌入式設(shè)計(jì)的需求一直是在盡可能長(zhǎng)的時(shí)間運(yùn)行應(yīng)用程序，同時(shí)消耗最小功耗的動(dòng)機(jī)。在電池供電的系統(tǒng)，這需要的是放大。此外，在電池供電的系統(tǒng)中，低功耗意味著更低的操作成本和更小的電池容量，從而使應(yīng)用程序更具可移動(dòng)性。當(dāng)能源價(jià)格和今天的綠色計(jì)劃一樣高時(shí)，確保嵌入式設(shè)計(jì)盡可能少地消耗能源在墻壁供電的應(yīng)用中也同樣重要。設(shè)計(jì)高功率的應(yīng)用程序還可以確保較小的開(kāi)銷(xiāo)來(lái)管理散熱和通過(guò)優(yōu)化功耗來(lái)控制熱源的產(chǎn)生。保持上述明顯的優(yōu)勢(shì)，今天的嵌入式應(yīng)用程序設(shè)計(jì)人員已經(jīng)不再忽視優(yōu)化電源的問(wèn)題。本文將通過(guò)分析目前大多數(shù)微控制器提供的各種電源模式，著重討論影響嵌入式系統(tǒng)功耗的主要因素。然后，我們將分析一個(gè)嵌入式應(yīng)用程序在功耗方面的實(shí)際例子，以及如何最大化其效率。

　　MCU power consumption

　　To begin， there are several points to be aware of when selecting a MCU or external components. Overall power consumption of an MCU is defined by its power consumption in different modes， typically active and standby （includes sleep， hibernate， etc.） and taking into account the power consumed to transition from one mode to another. Let us go through these power modes in more detail.

　　Active power consumption by an MCU is the power consumed when the MCU is running. As almost all controllers are based upon CMOS logic， power is consumed primarily during switching. As a starting point， let us analyze the power consumption of a CMOS inverter （Figure 1） which is the basic building block of any CMOS design.