我們現在處于(yu)一個全(quan)球無線互聯的(de)時(shi)代，幾乎沒有什么(me)比時(shi)刻保持(chi)手(shou)機(ji)或移動上(shang)網設(she)備(bei)處于(yu)通電(dian)(dian)(dian)(dian)(dian)狀(zhuang)態來的(de)重要(yao)。隨著便攜(xie)式(shi)和手(shou)持(chi)式(shi)設(she)備(bei)上(shang)的(de)功能不斷擴展，電(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian)器(qi)IC的(de)設(she)計人員(yuan)也面臨嚴峻的(de)考驗。高(gao)分(fen)辨率(lv)屏幕，更(geng)大的(de)存儲能力(li)以及設(she)備(bei)上(shang)的(de)新功能都增(zeng)加了電(dian)(dian)(dian)(dian)(dian)池的(de)負荷，這不僅僅需要(yao)更(geng)好的(de)電(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian)技術，而且還需具(ju)備(bei)高(gao)效的(de)電(dian)(dian)(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(le)提供(gong)傳統(tong)線形充(chong)(chong)電(dian)器所擁有的高(gao)效率(lv)之外(wai)，最大的優勢就(jiu)是能提高(gao)由電(dian)源提供(gong)的充(chong)(chong)電(dian)電(dian)流(liu)。當USB端口(kou)斷電(dian)時，可用的電(dian)流(liu)被限(xian)制在可能不(bu)到500mA，而此時，這(zhe)個優勢就(jiu)顯得尤為(wei)重要。更(geng)高(gao)的電(dian)流(liu)意(yi)味著更(geng)短的充(chong)(chong)電(dian)時間(jian)，這(zhe)完全符合消費者的需求。

　　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)(dian)(dian)(dian)(dian)器(qi)(qi)已有(you)較長(chang)的歷(li)史，充(chong)電(dian)(dian)(dian)(dian)(dian)方式(shi)比較簡單有(you)效，噪聲很小(xiao)，且沒(mei)有(you)太多外部(bu)元(yuan)件。但是，隨著便(bian)攜(xie)式(shi)設(she)備(bei)越來越復雜，新功(gong)能(neng)層出不窮(qiong)，高容量電(dian)(dian)(dian)(dian)(dian)池的需求就更加強烈。線形(xing)充(chong)電(dian)(dian)(dian)(dian)(dian)器(qi)(qi)的缺點是功(gong)耗太大，特別(bie)是在設(she)備(bei)邊充(chong)電(dian)(dian)(dian)(dian)(dian)邊使用的時(shi)候尤為(wei)明顯(xian)，此(ci)時(shi)產生的熱量可(ke)能(neng)損壞系統或電(dian)(dian)(dian)(dian)(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(shi)用盡可能少的電(dian)量，為電(dian)池提供更高的電(dian)流。從過往經驗來看，這類(lei)IC一(yi)(yi)般會存在一(yi)(yi)些噪(zao)聲問題。此外，前幾代(dai)的開關式(shi)充電(dian)器還(huan)需要一(yi)(yi)些外部元件。

　　然而(er)，開關式電(dian)(dian)池拓撲結(jie)構的優勢(shi)也是顯而(er)易見。這(zhe)些優勢(shi)包括更(geng)高的效率和(he)更(geng)低的功耗，還有更(geng)短(duan)的充電(dian)(dian)時間(jian)。此類裝置還能利用較高的輸入電(dian)(dian)壓充電(dian)(dian)，使用成(cheng)本(ben)較低的非(fei)穩壓適配器。還可以提高來自限(xian)流電(dian)(dian)流源的充電(dian)(dian)電(dian)(dian)流。

　　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)(yi)(yi)在(zai)(zai)使用(yong)開關(guan)(guan)充(chong)(chong)電(dian)(dian)器(qi)時(shi)提供高(gao)充(chong)(chong)電(dian)(dian)電(dian)(dian)流(liu)，且對系統(tong)的熱(re)影響非常小，而在(zai)(zai)低電(dian)(dian)流(liu)充(chong)(chong)電(dian)(dian)模(mo)式(shi)(shi)下切換(huan)(huan)(huan)到線(xian)性(xing)充(chong)(chong)電(dian)(dian)器(qi)，以(yi)(yi)(yi)減(jian)少噪(zao)聲。這種可提供線(xian)性(xing)模(mo)式(shi)(shi)的PWM開關(guan)(guan)模(mo)式(shi)(shi)充(chong)(chong)電(dian)(dian)器(qi)可以(yi)(yi)(yi)在(zai)(zai)全恒(heng)流(liu)(快速充(chong)(chong)電(dian)(dian))條(tiao)件下實(shi)現高(gao)效(xiao)率。開關(guan)(guan)充(chong)(chong)電(dian)(dian)器(qi)可利用(yong)PWM開關(guan)(guan)穩壓器(qi)控制高(gao)達2A的恒(heng)流(liu)充(chong)(chong)電(dian)(dian)。當電(dian)(dian)池處于預處理過(guo)程(cheng)以(yi)(yi)(yi)及恒(heng)壓尖(jian)峰(taper)充(chong)(chong)電(dian)(dian)模(mo)式(shi)(shi)快結束時(shi)，設(she)備會自(zi)動轉換(huan)(huan)(huan)到線(xian)形模(mo)式(shi)(shi)，以(yi)(yi)(yi)降低噪(zao)聲，并利用(yong)開關(guan)(guan)模(mo)式(shi)(shi)加快充(chong)(chong)電(dian)(dian)。一旦充(chong)(chong)電(dian)(dian)電(dian)(dian)流(liu)值低于300mA，線(xian)性(xing)模(mo)式(shi)(shi)會完全啟動，開關(guan)(guan)轉換(huan)(huan)(huan)器(qi)產生(sheng)的噪(zao)聲就會消除。

　　但是，現在充(chong)(chong)(chong)電(dian)(dian)技(ji)術有了進一(yi)步的發展(zhan)。例如(ru)，一(yi)種用(yong)于新型(xing)手(shou)持(chi)式(shi)設備的單節鋰(li)離子/聚合物電(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)器解決方(fang)案，它的充(chong)(chong)(chong)電(dian)(dian)電(dian)(dian)流高(gao)達1A，具備先(xian)進的電(dian)(dian)充(chong)(chong)(chong)滿顯示功能，可(ke)(ke)以實現全程充(chong)(chong)(chong)電(dian)(dian)系(xi)統(tong)監控。符(fu)合USB標準(zhun)的100mA/500mA充(chong)(chong)(chong)電(dian)(dian)電(dian)(dian)流設置有助于實現可(ke)(ke)編程預(yu)充(chong)(chong)(chong)電(dian)(dian)和快(kuai)速充(chong)(chong)(chong)電(dian)(dian)。許多產(chan)品還具備電(dian)(dian)池溫度監測功能，以確保(bao)安全充(chong)(chong)(chong)電(dian)(dian)。

　　Intersil等公司正(zheng)在開(kai)發新(xin)一代充電(dian)器IC技(ji)術。這些完全集成的解決方案(an)非常適(shi)合(he)緊(jin)湊型(xing)應用，還能為(wei)高功率應用提供充電(dian)控制功能。目前(qian)(qian)，充電(dian)電(dian)壓精(jing)度能達(da)到0.5%，較前(qian)(qian)幾年的1%有很大改(gai)善(shan)。開(kai)關(guan)頻率可(ke)(ke)達(da)3MHz，而(er)且(qie)新(xin)型(xing)開(kai)關(guan)充電(dian)器可(ke)(ke)提供高達(da)2A的充電(dian)電(dian)流，最新(xin)的一個應用實例是ISL9220，它適(shi)用于一節和兩節鋰離子電(dian)池應用。

　　另外，新(xin)設計(ji)還可(ke)以限制泄漏，目前在沒(mei)有加(jia)上輸入功(gong)率時(shi)，典(dian)型(xing)的泄漏電流已低于0.5uA。而且這些(xie)改進還可(ke)以用(yong)于更小的封裝，如4mm×4mm QFN或2mm×2mm CSP，以節省手持(chi)式(shi)設備的設計(ji)空間。

　　最新的電池充電器IC還(huan)能夠監視輸入電(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)壓(ya)和充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流。當三(san)個參數中(zhong)任意一(yi)個超出特定(ding)限額時(shi)，該IC就會關閉內部(bu)N溝道MOSFET，使充(chong)電(dian)(dian)(dian)(dian)系統停止對電(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)。利用這(zhe)些(xie)重要的(de)(de)器件可以靈活地提高(gao)效率，這(zhe)對持續(xu)增長、功(gong)能不斷擴充(chong)的(de)(de)移動、手持式(shi)產品是至關重要的(de)(de)。