我(wo)們(men)現在處于一個全球(qiu)無(wu)線(xian)互聯的(de)時(shi)代，幾乎沒(mei)有什么比時(shi)刻保持(chi)手機或移動(dong)上(shang)網設(she)(she)備處于通電(dian)狀態(tai)來的(de)重(zhong)要。隨著(zhu)便攜式和手持(chi)式設(she)(she)備上(shang)的(de)功能(neng)不斷擴展，電(dian)池(chi)充電(dian)器IC的(de)設(she)(she)計人員也面臨(lin)嚴(yan)峻(jun)的(de)考驗。高分辨(bian)率屏幕，更(geng)大的(de)存儲能(neng)力(li)以及設(she)(she)備上(shang)的(de)新功能(neng)都增(zeng)加了電(dian)池(chi)的(de)負(fu)荷(he)，這不僅(jin)僅(jin)需(xu)要更(geng)好的(de)電(dian)池(chi)充電(dian)技術，而且還需(xu)具備高效的(de)電(dian)源(yuan)管理能(neng)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(tong)線形充電(dian)(dian)(dian)器所(suo)擁有的(de)高效(xiao)率(lv)之(zhi)外，最(zui)大的(de)優(you)(you)勢(shi)就(jiu)是能提高由電(dian)(dian)(dian)源提供的(de)充電(dian)(dian)(dian)電(dian)(dian)(dian)流。當(dang)USB端口斷電(dian)(dian)(dian)時(shi)，可用(yong)的(de)電(dian)(dian)(dian)流被限(xian)制在可能不到500mA，而此時(shi)，這(zhe)個(ge)優(you)(you)勢(shi)就(jiu)顯(xian)得尤為重(zhong)要。更高的(de)電(dian)(dian)(dian)流意味著更短的(de)充電(dian)(dian)(dian)時(shi)間，這(zhe)完全(quan)符合消費(fei)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(xian)性充(chong)電(dian)器已有(you)較長的歷史，充(chong)電(dian)方式比較簡單有(you)效，噪聲很小，且沒有(you)太(tai)多外部元(yuan)件。但是(shi)，隨著便攜式設備越(yue)來(lai)越(yue)復(fu)雜，新功能層出不窮，高容(rong)量電(dian)池的需求(qiu)就更(geng)加強烈。線(xian)形充(chong)電(dian)器的缺點是(shi)功耗(hao)太(tai)大，特別是(shi)在設備邊(bian)(bian)充(chong)電(dian)邊(bian)(bian)使(shi)用的時候尤為明(ming)顯(xian)，此時產(chan)生的熱量可能損壞(huai)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(ta)可(ke)以(yi)使用盡可(ke)能(neng)少的電(dian)量，為(wei)電(dian)池(chi)提(ti)供更高(gao)的電(dian)流。從過往經驗來看(kan)，這(zhe)類IC一般會存在(zai)一些噪聲問題。此外(wai)，前幾代的開關式(shi)充(chong)電(dian)器(qi)還需要(yao)一些外(wai)部元件。

　　然而，開關式(shi)電(dian)(dian)池(chi)拓(tuo)撲結構的(de)(de)優勢也(ye)是顯(xian)而易見。這些優勢包括更(geng)高的(de)(de)效率和更(geng)低(di)的(de)(de)功耗，還有(you)更(geng)短的(de)(de)充電(dian)(dian)時間。此類裝置還能(neng)利(li)用較高的(de)(de)輸入電(dian)(dian)壓充電(dian)(dian)，使用成本較低(di)的(de)(de)非(fei)穩壓適配(pei)器。還可以提高來自(zi)限(xian)流電(dian)(dian)流源的(de)(de)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)在(zai)使用(yong)開關(guan)充(chong)(chong)(chong)電(dian)(dian)(dian)器時提(ti)供(gong)高充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)，且對系(xi)統(tong)的熱影響(xiang)非常小，而在(zai)低電(dian)(dian)(dian)流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)模(mo)式(shi)(shi)下切換到線性充(chong)(chong)(chong)電(dian)(dian)(dian)器，以(yi)(yi)減少(shao)噪聲。這種可提(ti)供(gong)線性模(mo)式(shi)(shi)的PWM開關(guan)模(mo)式(shi)(shi)充(chong)(chong)(chong)電(dian)(dian)(dian)器可以(yi)(yi)在(zai)全恒流(liu)(快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian))條(tiao)件下實現(xian)高效率(lv)。開關(guan)充(chong)(chong)(chong)電(dian)(dian)(dian)器可利用(yong)PWM開關(guan)穩壓器控制(zhi)高達(da)2A的恒流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)。當電(dian)(dian)(dian)池處于預處理過程以(yi)(yi)及恒壓尖峰(taper)充(chong)(chong)(chong)電(dian)(dian)(dian)模(mo)式(shi)(shi)快結(jie)束時，設備會自(zi)動轉換到線形(xing)模(mo)式(shi)(shi)，以(yi)(yi)降(jiang)低噪聲，并利用(yong)開關(guan)模(mo)式(shi)(shi)加快充(chong)(chong)(chong)電(dian)(dian)(dian)。一(yi)旦充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)值(zhi)低于300mA，線性模(mo)式(shi)(shi)會完全啟(qi)動，開關(guan)轉換器產生的噪聲就(jiu)會消除。

　　但是，現(xian)(xian)(xian)在充(chong)(chong)電(dian)(dian)技術(shu)有了(le)進(jin)一步(bu)的(de)(de)發展。例(li)如，一種(zhong)用于新型手持式設(she)備的(de)(de)單節鋰離子/聚合(he)物電(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)器解決方案，它的(de)(de)充(chong)(chong)電(dian)(dian)電(dian)(dian)流高達1A，具備先進(jin)的(de)(de)電(dian)(dian)充(chong)(chong)滿(man)顯(xian)示功能(neng)，可以實現(xian)(xian)(xian)全程充(chong)(chong)電(dian)(dian)系(xi)統(tong)監控(kong)。符合(he)USB標(biao)準的(de)(de)100mA/500mA充(chong)(chong)電(dian)(dian)電(dian)(dian)流設(she)置有助于實現(xian)(xian)(xian)可編程預充(chong)(chong)電(dian)(dian)和快速充(chong)(chong)電(dian)(dian)。許多產品還具備電(dian)(dian)池(chi)溫度監測功能(neng)，以確保安全充(chong)(chong)電(dian)(dian)。

　　Intersil等公司正在開發新(xin)一(yi)代充(chong)電(dian)(dian)器IC技術。這些(xie)完(wan)全(quan)集成的(de)解(jie)決方案非常適合緊湊型(xing)應用(yong)(yong)，還能(neng)(neng)為高(gao)功(gong)率應用(yong)(yong)提(ti)供充(chong)電(dian)(dian)控制功(gong)能(neng)(neng)。目前，充(chong)電(dian)(dian)電(dian)(dian)壓(ya)精(jing)度(du)能(neng)(neng)達到0.5%，較(jiao)前幾年的(de)1%有很(hen)大改(gai)善。開關(guan)頻率可達3MHz，而且新(xin)型(xing)開關(guan)充(chong)電(dian)(dian)器可提(ti)供高(gao)達2A的(de)充(chong)電(dian)(dian)電(dian)(dian)流，最新(xin)的(de)一(yi)個(ge)應用(yong)(yong)實例(li)是ISL9220，它適用(yong)(yong)于一(yi)節和兩節鋰離子(zi)電(dian)(dian)池應用(yong)(yong)。

　　另外，新設計還可以(yi)(yi)限制泄(xie)漏(lou)，目前在沒有加上輸入功率時，典型的(de)泄(xie)漏(lou)電流已低于0.5uA。而且這(zhe)些改進還可以(yi)(yi)用(yong)于更小的(de)封裝，如4mm×4mm QFN或2mm×2mm CSP，以(yi)(yi)節省手持式設備的(de)設計空(kong)間(jian)。

　　最新的電池充電器IC還能(neng)夠監視輸(shu)入電(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)壓和(he)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)。當(dang)三個參數中(zhong)任意一(yi)個超出特定(ding)限額時，該IC就會關閉內(nei)部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)。利用這些重要的器件可以靈活地(di)提高效率，這對持(chi)續增長、功能(neng)不(bu)斷擴充(chong)的移動、手持(chi)式(shi)產品是至關重要的。