我們現在處(chu)于(yu)一個(ge)全球(qiu)無線互聯的(de)(de)時代，幾乎沒(mei)有(you)什么比時刻(ke)保持(chi)手機或移(yi)動(dong)上網設(she)備(bei)處(chu)于(yu)通電(dian)(dian)狀(zhuang)態來的(de)(de)重要。隨著(zhu)便(bian)攜式(shi)和手持(chi)式(shi)設(she)備(bei)上的(de)(de)功能不(bu)斷(duan)擴展，電(dian)(dian)池(chi)充(chong)電(dian)(dian)器IC的(de)(de)設(she)計人員也面臨嚴(yan)峻的(de)(de)考(kao)驗。高分辨率屏幕，更(geng)大的(de)(de)存儲能力(li)以及設(she)備(bei)上的(de)(de)新功能都增加了電(dian)(dian)池(chi)的(de)(de)負荷(he)，這不(bu)僅僅需(xu)要更(geng)好(hao)的(de)(de)電(dian)(dian)池(chi)充(chong)電(dian)(dian)技術，而(er)且還需(xu)具(ju)備(bei)高效的(de)(de)電(dian)(dian)源管理能力(li)。

　　降低功耗以延長電池壽命，這一直是手持式電源管理的源動力。然而，現在消費者對充電器的充電效率也有所期待，希望能夠縮短設備的充電時間，新一代的充電器設計采用開關充電器替代傳統的線形充電器，除了(le)提供傳統線形(xing)充(chong)電(dian)(dian)(dian)器所擁有的(de)高(gao)(gao)效率(lv)之外，最大的(de)優勢(shi)就是能提高(gao)(gao)由電(dian)(dian)(dian)源提供的(de)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流。當USB端口斷電(dian)(dian)(dian)時，可用的(de)電(dian)(dian)(dian)流被限制在可能不到500mA，而(er)此時，這個優勢(shi)就顯(xian)得尤為重要。更高(gao)(gao)的(de)電(dian)(dian)(dian)流意味著更短的(de)充(chong)電(dian)(dian)(dian)時間(jian)，這完全符(fu)合消費者的(de)需求。

　　現在，大多數手持式設備都采用了兩種電池充電器，一種是線性充電器，另一種是開關充電器。線性充(chong)電(dian)器已有較長的歷史(shi)，充(chong)電(dian)方(fang)式比較簡(jian)單有效，噪聲(sheng)很小，且(qie)沒有太多外部元件。但是，隨著便攜式設備越來越復雜，新功(gong)能層出不窮(qiong)，高容量電(dian)池的需求就更加強(qiang)烈。線形充(chong)電(dian)器的缺點是功(gong)耗太大，特別是在設備邊充(chong)電(dian)邊使用的時候尤為明顯，此時產(chan)生的熱量可能損壞系統或(huo)電(dian)池。

　　可供選擇的有開關充電器或開關模式電池充電器IC，它可(ke)以使(shi)用盡可(ke)能少(shao)的電(dian)量，為電(dian)池提供(gong)更高的電(dian)流。從(cong)過往經驗來看，這類IC一(yi)般會存在一(yi)些噪聲問題。此外，前幾代的開(kai)關式充電(dian)器還需要一(yi)些外部元件。

　　然而(er)，開(kai)關式電(dian)(dian)池拓撲結構(gou)的優勢也是顯而(er)易(yi)見。這些(xie)優勢包(bao)括(kuo)更(geng)高的效率和更(geng)低的功耗，還有更(geng)短的充(chong)電(dian)(dian)時間。此類(lei)裝置(zhi)還能利用較高的輸入電(dian)(dian)壓充(chong)電(dian)(dian)，使用成本較低的非穩壓適(shi)配(pei)器(qi)。還可以提高來自限流(liu)電(dian)(dian)流(liu)源的充(chong)電(dian)(dian)電(dian)(dian)流(liu)。

　　開關充電器通常在輕負載運行時會產生噪聲，特別是在預處理過程中。隨著噪聲的減少，開關充電器會進入脈沖跳躍(pulse skipping)模式運行。在脈沖跳躍模式中，PWM頻率異步變化。目前開發的電池充電器IC，可(ke)以在使(shi)用(yong)(yong)開關(guan)(guan)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)時(shi)提供(gong)(gong)高充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流，且對系統的(de)(de)熱影響非常(chang)小，而在低電(dian)(dian)(dian)(dian)流充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)模(mo)(mo)式(shi)(shi)(shi)下(xia)切換(huan)到線(xian)(xian)性充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)，以減少噪(zao)聲。這種可(ke)提供(gong)(gong)線(xian)(xian)性模(mo)(mo)式(shi)(shi)(shi)的(de)(de)PWM開關(guan)(guan)模(mo)(mo)式(shi)(shi)(shi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)可(ke)以在全恒(heng)流(快速充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian))條件(jian)下(xia)實現高效(xiao)率(lv)。開關(guan)(guan)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)可(ke)利(li)用(yong)(yong)PWM開關(guan)(guan)穩壓器(qi)控制高達2A的(de)(de)恒(heng)流充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)。當電(dian)(dian)(dian)(dian)池處于預處理過程以及恒(heng)壓尖峰(feng)(taper)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)模(mo)(mo)式(shi)(shi)(shi)快結束(shu)時(shi)，設備(bei)會自動轉換(huan)到線(xian)(xian)形模(mo)(mo)式(shi)(shi)(shi)，以降(jiang)低噪(zao)聲，并利(li)用(yong)(yong)開關(guan)(guan)模(mo)(mo)式(shi)(shi)(shi)加快充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)。一旦充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流值低于300mA，線(xian)(xian)性模(mo)(mo)式(shi)(shi)(shi)會完全啟動，開關(guan)(guan)轉換(huan)器(qi)產生的(de)(de)噪(zao)聲就會消除。

　　但(dan)是，現在充(chong)電(dian)(dian)(dian)(dian)(dian)技(ji)術有了進(jin)一(yi)步的(de)發展。例如，一(yi)種用于新(xin)型手持式設備的(de)單節鋰離子/聚合物電(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)器解決方(fang)案(an)，它的(de)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)高(gao)達(da)1A，具(ju)備先進(jin)的(de)電(dian)(dian)(dian)(dian)(dian)充(chong)滿(man)顯(xian)示功能，可(ke)以實現全程(cheng)(cheng)充(chong)電(dian)(dian)(dian)(dian)(dian)系統監控。符合USB標準的(de)100mA/500mA充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)設置有助于實現可(ke)編(bian)程(cheng)(cheng)預充(chong)電(dian)(dian)(dian)(dian)(dian)和(he)快(kuai)速(su)充(chong)電(dian)(dian)(dian)(dian)(dian)。許多產品還具(ju)備電(dian)(dian)(dian)(dian)(dian)池溫度監測功能，以確保安全充(chong)電(dian)(dian)(dian)(dian)(dian)。

　　Intersil等(deng)公司正在開(kai)發(fa)新(xin)一代充(chong)電(dian)器IC技術。這(zhe)些完全集成的解決方案非常適(shi)合緊湊型應用(yong)，還能(neng)為高功率應用(yong)提(ti)(ti)供充(chong)電(dian)控制(zhi)功能(neng)。目前(qian)，充(chong)電(dian)電(dian)壓(ya)精度(du)能(neng)達到0.5%，較前(qian)幾(ji)年的1%有(you)很(hen)大(da)改善。開(kai)關頻率可達3MHz，而(er)且新(xin)型開(kai)關充(chong)電(dian)器可提(ti)(ti)供高達2A的充(chong)電(dian)電(dian)流，最新(xin)的一個應用(yong)實例是ISL9220，它(ta)適(shi)用(yong)于一節和兩節鋰離子電(dian)池應用(yong)。

　　另外，新設(she)(she)計(ji)(ji)還可以限制泄漏，目前(qian)在沒有(you)加上輸(shu)入功率時，典型的(de)泄漏電流已低于0.5uA。而且(qie)這些改進還可以用于更小的(de)封(feng)裝，如4mm×4mm QFN或(huo)2mm×2mm CSP，以節省手持(chi)式設(she)(she)備的(de)設(she)(she)計(ji)(ji)空間。

　　最新的電池充電器IC還能夠(gou)監視輸入電(dian)壓(ya)、電(dian)池(chi)(chi)電(dian)壓(ya)和充(chong)電(dian)電(dian)流。當三(san)個參數中任意一個超(chao)出特定限額時，該IC就會關閉內部(bu)N溝道MOSFET，使充(chong)電(dian)系統停(ting)止對(dui)電(dian)池(chi)(chi)充(chong)電(dian)。利用這些重要(yao)的器件可以靈活地提高效率，這對(dui)持續增長、功能不(bu)斷擴充(chong)的移(yi)動、手持式產品是至(zhi)關重要(yao)的。