延長鋰離子電池壽命的設(shè)計技術(shù)

　　便攜式設(shè)備中的電源管理是電子工程師面臨的最嚴峻挑戰(zhàn)之一。消費者需要從他們的設(shè)備，大量的功能，以及一個大，明亮多彩的觸摸屏的即時反應(yīng)。此外，現(xiàn)在許多便攜式設(shè)備都采用無線連接，這就給電池帶來了進一步的需求。然而，用戶希望電池，一個敏感的鋰離子（李離子）電池，需要仔細充電從一些來源，包括USB插座，持續(xù)至少一天，然后迅速刷新。

　　設(shè)計一個滿足這些矛盾問題的電源管理系統(tǒng)是很困難的。然而，有一些有助于延長電池壽命的有效的設(shè)計技術(shù)。此外，關(guān)鍵的半導體廠商已經(jīng)使生活更容易通過提供電源管理單元（PMU），整合一些，甚至所有，用于便攜式設(shè)備的高效電源所需的功能。

　　本文提供了在手持設(shè)備的能源消耗最小化的一些設(shè)計原則和重點的新的集成PMU

　　Lithium energy

　　Li-ion cells， the mainstay power source for high-demand portable devices， have improved in energy density （energy capacity/volume） by only about seven percent per year since they were first commercialized in 1991. Compared to the rapid increase in silicon chip performance， that is a snail’s pace. Nonetheless， lithium-based power for portable devices is particularly appealing for two key reasons： Lithium is the most electropositive metal （i.e.， it exhibits a high positive charge）， lending itself to batteries with higher voltages than other rechargeable types （around 3.6 V compared to 1.2 to 1.5 V for nickel-based batteries）; and it is the lightest metal （only two elements， hydrogen and helium， are lighter） allowing the storage of more energy per kilogram than most other metals （around 3，900 Ahr/kg compared to 260 Ahr/kg for lead）。1 Other benefits include thousands of recharges and no occurrence of the “memory effect” that plagued early nickel cadmium （NiCd） rechargeable cells.