我們(men)現在處于一個(ge)全(quan)球無線(xian)互(hu)聯的(de)時代(dai)，幾乎沒有什么比時刻(ke)保持手機或移動上網設(she)備處于通(tong)電(dian)(dian)(dian)狀(zhuang)態來的(de)重要。隨著便攜式和手持式設(she)備上的(de)功(gong)能不斷擴展(zhan)，電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)器(qi)IC的(de)設(she)計人員也面臨嚴峻的(de)考驗。高分辨率屏幕，更大的(de)存儲(chu)能力(li)以及設(she)備上的(de)新功(gong)能都增(zeng)加(jia)了電(dian)(dian)(dian)池的(de)負荷，這不僅僅需要更好的(de)電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)技(ji)術，而且還需具(ju)備高效的(de)電(dian)(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，除了提供傳統線形充電(dian)器所擁有(you)的(de)高效率(lv)之外，最大的(de)優(you)(you)勢就是能(neng)提高由電(dian)源(yuan)提供的(de)充電(dian)電(dian)流。當USB端口斷電(dian)時(shi)(shi)，可(ke)用的(de)電(dian)流被限制(zhi)在可(ke)能(neng)不(bu)到500mA，而此時(shi)(shi)，這個優(you)(you)勢就顯得尤為重要。更高的(de)電(dian)流意味著更短的(de)充電(dian)時(shi)(shi)間，這完全(quan)符合(he)消費者(zhe)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。線性充電(dian)器已有(you)較(jiao)長的(de)歷(li)史，充電(dian)方式(shi)比(bi)較(jiao)簡單有(you)效，噪聲很小，且沒有(you)太多外部(bu)元件。但(dan)是(shi)，隨著便(bian)攜式(shi)設備(bei)越(yue)來(lai)越(yue)復雜，新功能(neng)層(ceng)出(chu)不窮，高容量電(dian)池的(de)需(xu)求就(jiu)更加(jia)強烈。線形充電(dian)器的(de)缺點是(shi)功耗太大，特(te)別是(shi)在設備(bei)邊(bian)(bian)充電(dian)邊(bian)(bian)使用的(de)時候(hou)尤為(wei)明(ming)顯，此時產生的(de)熱量可能(neng)損壞系統或電(dian)池。

　　可供選擇的有開關充電器或開關模式電池充電器IC，它可以使用(yong)盡可能(neng)少的電量，為電池(chi)提供更(geng)高的電流。從過往經驗來看，這類IC一(yi)般會存在一(yi)些噪聲問題。此外，前幾代的開關式充電器還需要一(yi)些外部元件。

　　然而(er)，開關式電(dian)(dian)(dian)池拓撲結構的(de)優勢(shi)也是顯而(er)易(yi)見。這些(xie)優勢(shi)包括更(geng)(geng)高的(de)效率和(he)更(geng)(geng)低的(de)功耗(hao)，還(huan)有更(geng)(geng)短的(de)充電(dian)(dian)(dian)時間。此類裝置還(huan)能利用(yong)較高的(de)輸入電(dian)(dian)(dian)壓充電(dian)(dian)(dian)，使(shi)用(yong)成本較低的(de)非穩(wen)壓適配器。還(huan)可以提高來自限(xian)流(liu)電(dian)(dian)(dian)流(liu)源(yuan)的(de)充電(dian)(dian)(dian)電(dian)(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，可以(yi)在使(shi)用開(kai)關(guan)充(chong)(chong)(chong)(chong)電(dian)(dian)器時(shi)(shi)提供(gong)高充(chong)(chong)(chong)(chong)電(dian)(dian)電(dian)(dian)流(liu)，且對(dui)系(xi)統的(de)熱影響非(fei)常小(xiao)，而在低電(dian)(dian)流(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)模(mo)(mo)式下切換到線性(xing)充(chong)(chong)(chong)(chong)電(dian)(dian)器，以(yi)減少噪聲(sheng)(sheng)。這種可提供(gong)線性(xing)模(mo)(mo)式的(de)PWM開(kai)關(guan)模(mo)(mo)式充(chong)(chong)(chong)(chong)電(dian)(dian)器可以(yi)在全(quan)恒流(liu)(快(kuai)速充(chong)(chong)(chong)(chong)電(dian)(dian))條件下實(shi)現高效率。開(kai)關(guan)充(chong)(chong)(chong)(chong)電(dian)(dian)器可利用PWM開(kai)關(guan)穩壓器控制高達2A的(de)恒流(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)。當電(dian)(dian)池處(chu)于(yu)預處(chu)理過程以(yi)及恒壓尖峰(taper)充(chong)(chong)(chong)(chong)電(dian)(dian)模(mo)(mo)式快(kuai)結束時(shi)(shi)，設(she)備會自動轉換到線形模(mo)(mo)式，以(yi)降(jiang)低噪聲(sheng)(sheng)，并利用開(kai)關(guan)模(mo)(mo)式加快(kuai)充(chong)(chong)(chong)(chong)電(dian)(dian)。一旦充(chong)(chong)(chong)(chong)電(dian)(dian)電(dian)(dian)流(liu)值(zhi)低于(yu)300mA，線性(xing)模(mo)(mo)式會完全(quan)啟動，開(kai)關(guan)轉換器產生的(de)噪聲(sheng)(sheng)就會消除(chu)。

　　但是，現在充(chong)(chong)(chong)電(dian)(dian)(dian)技術有(you)了進一步的發(fa)展。例(li)如，一種(zhong)用于新型(xing)手持式(shi)設(she)備(bei)的單節(jie)鋰離子/聚合(he)物電(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)解決方(fang)案(an)，它的充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流高達1A，具備(bei)先進的電(dian)(dian)(dian)充(chong)(chong)(chong)滿(man)顯示功(gong)能，可(ke)以實現全(quan)程充(chong)(chong)(chong)電(dian)(dian)(dian)系統監控(kong)。符合(he)USB標準的100mA/500mA充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流設(she)置有(you)助于實現可(ke)編程預充(chong)(chong)(chong)電(dian)(dian)(dian)和快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian)。許多產品還具備(bei)電(dian)(dian)(dian)池溫度監測功(gong)能，以確保安全(quan)充(chong)(chong)(chong)電(dian)(dian)(dian)。

　　Intersil等公司正(zheng)在開(kai)發新(xin)一代充(chong)(chong)電(dian)(dian)(dian)器IC技(ji)術。這些完全集成的解決方案(an)非常適(shi)合緊湊型應(ying)(ying)用(yong)(yong)(yong)，還能(neng)(neng)為高功率應(ying)(ying)用(yong)(yong)(yong)提供充(chong)(chong)電(dian)(dian)(dian)控制功能(neng)(neng)。目前(qian)，充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓精度能(neng)(neng)達到0.5%，較前(qian)幾(ji)年的1%有很(hen)大改善(shan)。開(kai)關頻率可(ke)達3MHz，而(er)且新(xin)型開(kai)關充(chong)(chong)電(dian)(dian)(dian)器可(ke)提供高達2A的充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流，最新(xin)的一個應(ying)(ying)用(yong)(yong)(yong)實例是(shi)ISL9220，它適(shi)用(yong)(yong)(yong)于(yu)一節(jie)和兩(liang)節(jie)鋰離子(zi)電(dian)(dian)(dian)池應(ying)(ying)用(yong)(yong)(yong)。

　　另外，新設(she)計還(huan)可(ke)以限制(zhi)泄(xie)(xie)漏，目前在(zai)沒(mei)有加上輸入功率(lv)時，典型(xing)的泄(xie)(xie)漏電流已低于0.5uA。而且這些改(gai)進還(huan)可(ke)以用于更(geng)小的封裝，如4mm×4mm QFN或2mm×2mm CSP，以節省(sheng)手持式設(she)備(bei)的設(she)計空(kong)間(jian)。

　　最新的電池充電器IC還能(neng)夠監視輸入電(dian)(dian)壓、電(dian)(dian)池電(dian)(dian)壓和(he)充(chong)電(dian)(dian)電(dian)(dian)流。當三個參數中任意一(yi)個超(chao)出特定(ding)限(xian)額時，該(gai)IC就會關閉內部N溝道MOSFET，使充(chong)電(dian)(dian)系(xi)統停止對電(dian)(dian)池充(chong)電(dian)(dian)。利用這些重要(yao)的器(qi)件可以(yi)靈活地提高效率，這對持續增長(chang)、功(gong)能(neng)不(bu)斷擴充(chong)的移動、手持式產(chan)品是至關重要(yao)的。