當今許多靠鋰離子電池供電的手持設備都內建有一個電池充電器，目前通常使用(yong)一種(zhong)(zhong)線性(xing)充(chong)電(dian)(dian)(dian)器(qi)給這(zhe)種(zhong)(zhong)電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)，但(dan)這(zhe)種(zhong)(zhong)充(chong)電(dian)(dian)(dian)器(qi)盡管(guan)操作更簡(jian)便和(he)成(cheng)本(ben)(ben)更低(di)，但(dan)它有一個主(zhu)要缺(que)點：能耗太高。當輸(shu)入電(dian)(dian)(dian)壓為高和(he)電(dian)(dian)(dian)池電(dian)(dian)(dian)壓為低(di)(已放電(dian)(dian)(dian)電(dian)(dian)(dian)池)時，線性(xing)充(chong)電(dian)(dian)(dian)器(qi)產生的熱量足以損壞自身(shen)或其(qi)它鄰近(jin)元(yuan)件。在(zai)本(ben)(ben)文中(zhong)，凌特技術(shu)公(gong)司提(ti)出了一種(zhong)(zhong)替代(dai)方案(an)，它可解(jie)決所(suo)有的過熱問題而且充(chong)電(dian)(dian)(dian)快(kuai)速。

　　當今(jin)許多靠電(dian)(dian)(dian)池(chi)供電(dian)(dian)(dian)的(de)手持(chi)設備都內建(jian)有一個(ge)(ge)電(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)(qi)。這(zhe)些電(dian)(dian)(dian)池(chi)通常都為(wei)鋰離子(zi)電(dian)(dian)(dian)池(chi)，并且其功率密度(du)可在(zai)(zai)范圍400mA小(xiao)(xiao)時(shi)(shi)到1.5A小(xiao)(xiao)時(shi)(shi)變化。你可以使用一種(zhong)線性充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)(qi)給(gei)這(zhe)種(zhong)電(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)，而且這(zhe)種(zhong)充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)(qi)通常比基(ji)于轉換(huan)器(qi)(qi)的(de)方案在(zai)(zai)外形上明顯(xian)更小(xiao)(xiao)，操作更簡(jian)便，成本更低，但(dan)它(ta)有一個(ge)(ge)主要(yao)缺點(dian)：能耗(hao)太高(gao)。當輸(shu)入電(dian)(dian)(dian)壓為(wei)高(gao)和(he)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓為(wei)低(已放電(dian)(dian)(dian)電(dian)(dian)(dian)池(chi))時(shi)(shi)，線性充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)(qi)產生的(de)熱(re)量足以損壞自(zi)身或其它(ta)鄰近(jin)元件。典型(xing)地，這(zhe)種(zhong)狀(zhuang)態(即電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓隨(sui)充(chong)(chong)(chong)電(dian)(dian)(dian)的(de)進行(xing)而升高(gao))只(zhi)是暫(zan)時(shi)(shi)現象(xiang)，但(dan)正(zheng)是這(zhe)些最糟糕的(de)狀(zhuang)態需要(yao)設計師在(zai)(zai)決(jue)定充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流與IC溫度(du)的(de)最大容許值(zhi)時(shi)(shi)必須充(chong)(chong)(chong)分地加以考慮。當然，一種(zhong)解決(jue)這(zhe)種(zhong)過(guo)熱(re)問題的(de)簡(jian)單方法(fa)是降低充(chong)(chong)(chong)電(dian)(dian)(dian)過(guo)程中整個(ge)(ge)恒流段的(de)充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流，但(dan)這(zhe)種(zhong)方法(fa)伴隨(sui)的(de)問題是充(chong)(chong)(chong)電(dian)(dian)(dian)時(shi)(shi)間的(de)相應延長。

　　不過，凌特技術公司現在提出了一種替代方案，即LTC1733鋰離子單電池線性充電器，它解決了所有的過熱問題且充電快速。這種新穎的IC采用內部反饋來調節充電電流和限制裸片溫度。這意味著更快的充電時間，因為設計師可以通過編程設定一個很高充電電流，而且不會冒任何損壞IC或任何其它元件的風險。這一性能直接帶來的另一好處是毋需設計過熱保護電路。為了進一步改進熱傳遞性，LTC1733采用了熱增強型10針MSOP封裝。該IC只需要3個外部元件便可提供一個完整的鋰離子充電器解決方案。

　　一個(ge)內(nei)部功率(lv)MOSFET允許編程設定的(de)(de)(de)(de)最大充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)可(ke)達1.5A，精度為7%，以(yi)確保(bao)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)快速和(he)完(wan)(wan)全。這(zhe)種內(nei)部MOSFET還可(ke)省掉一個(ge)外部電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)敏感電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻或(huo)遏流(liu)(liu)二極管(guan)，最終的(de)(de)(de)(de)無負(fu)載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓是引腳可(ke)選的(de)(de)(de)(de)，或(huo)為4.1V或(huo)為 4.2V，精度是1%，這(zhe)可(ke)防止(zhi)過(guo)充(chong)帶來的(de)(de)(de)(de)危險或(huo)欠(qian)充(chong)造成的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)容量(liang)不足(zu)。遵從電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)制造商的(de)(de)(de)(de)使用要求(qiu)，LTC1733包含了(le)一個(ge)可(ke)編程充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)終止(zhi)定時器和(he)熱敏電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻輸(shu)入，以(yi)保(bao)證充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)全過(guo)程的(de)(de)(de)(de)溫度符合要求(qiu)。狀態輸(shu)出包括：用以(yi)指示充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)后(hou)期狀態的(de)(de)(de)(de)C/10充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)檢(jian)測、決定充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)是否可(ke)以(yi)進(jin)行下(xia)去的(de)(de)(de)(de)壁式電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源適(shi)配器狀態檢(jian)測、充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)監測、以(yi)及用以(yi)識別(bie)壞電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)(de)錯誤檢(jian)測。低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)調理電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(滴充(chong))可(ke)安全地為過(guo)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并自動(dong)續充(chong)以(yi)確保(bao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)總能(neng)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)完(wan)(wan)全。當沒(mei)有(you)壁式電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源適(shi)配器或(huo)該部件關閉的(de)(de)(de)(de)時候，為保(bao)持電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)能(neng)量(liang)， LTC1733的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)漏電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)降到5(A以(yi)下(xia)。

　　給電池充電
　　給單電(dian)(dian)池(chi)鋰離子電(dian)(dian)池(chi)系統充(chong)電(dian)(dian)時(shi)(shi)，用(yong)戶須在VCC腳處施加至少4.5V的(de)輸入(ru)電(dian)(dian)壓。ACPR腳隨(sui)后降(jiang)為(wei)低(di)電(dian)(dian)平(pull low)，指示(shi)輸入(ru)電(dian)(dian)壓條件已滿(man)足(見圖2)。此外，必須用(yong)一個1%的(de)電(dian)(dian)阻器(qi)把PROG與GND相連，使額定充(chong)電(dian)(dian)電(dian)(dian)流設(she)定為(wei)100V/RPROG。而后CHPG腳為(wei)低(di)電(dian)(dian)平，指示(shi)充(chong)電(dian)(dian)循(xun)環開始。TIMER和GND之間用(yong)電(dian)(dian)容器(qi)連接，充(chong)電(dian)(dian)終止時(shi)(shi)間設(she)定為(wei)3小時(shi)(shi)/100nF。

　　如果在充(chong)電(dian)(dian)(dian)(dian)循(xun)環(huan)開始時(shi)BAT腳的(de)電(dian)(dian)(dian)(dian)壓(ya)低于2.48V，那么，充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)將(jiang)為設(she)定(ding)(ding)值的(de)1/10，以使電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)足(zu)夠高(gao)，安全實現(xian)全充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)充(chong)電(dian)(dian)(dian)(dian)(見圖3)。如果電(dian)(dian)(dian)(dian)池(chi)損壞，且(qie)在1/4的(de)設(she)定(ding)(ding)終(zhong)止時(shi)間內電(dian)(dian)(dian)(dian)壓(ya)都(dou)升不到(dao)2.48V以上(shang)(shang)，則充(chong)電(dian)(dian)(dian)(dian)循(xun)環(huan)終(zhong)止，且(qie)FAULT狀(zhuang)態輸(shu)出(chu)將(jiang)鎖存為低電(dian)(dian)(dian)(dian)平，指示電(dian)(dian)(dian)(dian)池(chi)已壞。ACPR、CHRG和FAULT三(san)個狀(zhuang)態輸(shu)出(chu)腳全都(dou)產(chan)生(sheng)足(zu)夠的(de)電(dian)(dian)(dian)(dian)流(liu)衰(shuai)弱量，使LED亮燈。一(yi)旦電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)升到(dao)2.48V以上(shang)(shang)(充(chong)電(dian)(dian)(dian)(dian)循(xun)環(huan)開始后不久會明顯表現(xian)出(chu)來)，LTC1733將(jiang)為電(dian)(dian)(dian)(dian)池(chi)提供(gong)由RPROG設(she)定(ding)(ding)的(de)恒定(ding)(ding)電(dian)(dian)(dian)(dian)流(liu)。LTC1733將(jiang)一(yi)直保(bao)持恒流(liu)模(mo)式，直到(dao)BAT腳的(de)電(dian)(dian)(dian)(dian)壓(ya)接近(jin)所選擇的(de)最(zui)終(zhong)浮置電(dian)(dian)(dian)(dian)壓(ya)(SEL=0V時(shi)為 4.1V ，SEL=VCC時(shi)為4.2V)為止。此后，器件進入恒壓(ya)模(mo)式。

　　在恒壓模式下，LTC1733將開始(shi)降(jiang)低充電(dian)電(dian)流以(yi)保持BAT腳的恒壓而非恒流輸出。當電(dian)流降(jiang)至(zhi)最大(da)設定(ding)充電(dian)電(dian)流的10%時，內部比(bi)較器會斷(duan)開CHRG腳，并將一(yi)弱電(dian)流源(約(yue)25(A)接地，以(yi)顯示(shi)接近充電(dian)結束(C/10)狀(zhuang)態。

　　與電流達到C/10時便結束充電過程的電池充電器不同，LTC1733在到(dao)(dao)達C/10點后，只要(yao)終(zhong)止(zhi)定時(shi)器時(shi)間不到(dao)(dao)，會繼續給電(dian)(dian)池(chi)充(chong)電(dian)(dian)，以保證電(dian)(dian)池(chi)完全充(chong)滿(man)。在C/10處(chu)終(zhong)止(zhi)充(chong)電(dian)(dian)過程使電(dian)(dian)池(chi)只能充(chong)到(dao)(dao)其容(rong)量的(de)90%到(dao)(dao)95%，而(er)在C/10后繼續充(chong)并按時(shi)間要(yao)求結束(shu)可使電(dian)(dian)池(chi)的(de)容(rong)量充(chong)到(dao)(dao)100%。一(yi)旦充(chong)電(dian)(dian)結束(shu)，CHRG腳便呈現(xian)高阻抗狀態。

    電池的再充電
    假定在第一次(ci)充(chong)(chong)電(dian)(dian)(dian)(dian)時，電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)已充(chong)(chong)到(dao)了(le)3.95V(SEL = 0V時) 或(huo)4.05V (SEL = VCC時)以上，那么LTC1733可對電(dian)(dian)(dian)(dian)池(chi)(chi)進行再充(chong)(chong)電(dian)(dian)(dian)(dian)。一旦(dan)超出這些閾(yu)值，如果電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)因電(dian)(dian)(dian)(dian)池(chi)(chi)負載的(de)存在或(huo)電(dian)(dian)(dian)(dian)池(chi)(chi)的(de)自放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)而(er)掉到(dao)3.9V (SEL = 0V)或(huo)4.0V (SEL = VCC)以下時，則新一輪的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)循(xun)環開始了(le)。再充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)路(lu)集結(jie)BAT腳電(dian)(dian)(dian)(dian)壓(ya)數毫(hao)秒，以防止充(chong)(chong)電(dian)(dian)(dian)(dian)循(xun)環重啟造(zao)成(cheng)的(de)瞬態沖擊。

    熱調節
　　LTC1733的(de)(de)另一(yi)個特(te)性(xing)是具(ju)有(you)內部(bu)熱(re)調節回路。如果高功(gong)率操(cao)作或高的(de)(de)環境溫(wen)度(du)導致LTC1733的(de)(de)溫(wen)度(du)接近105(C，那么(me)充(chong)電(dian)電(dian)流(liu)會自動降低以將溫(wen)度(du)保持在(zai)105(C左右 (板溫(wen)度(du)通常低于(yu)85(C)，這便是所(suo)謂(wei)的(de)(de)恒(heng)溫(wen)模式。這一(yi)特(te)性(xing)允許(xu)用(yong)戶基于(yu)具(ju)體(ti)的(de)(de)工作條件設定充(chong)電(dian)電(dian)流(liu)，并去掉許(xu)多線性(xing)應用(yong)必需的(de)(de)復雜過熱(re)保護設計。

　　LTC1733會自(zi)動監(jian)視最糟狀態，這一(yi)特性(xing)除(chu)可保(bao)(bao)護LTC1733外(wai)，還能(neng)去除(chu)板上的“熱(re)(re)點”區，從而(er)保(bao)(bao)護周邊元件。其它(ta)的電(dian)(dian)池充電(dian)(dian)器(qi)，其熱(re)(re)關(guan)閉(bi)(bi)特性(xing)只(zhi)是簡(jian)單(dan)地在極高(gao)溫(wen)度下(一(yi)般(ban)是150(C)關(guan)閉(bi)(bi)充電(dian)(dian)器(qi)而(er)已。這種基于溫(wen)度的關(guan)閉(bi)(bi)特性(xing)允許電(dian)(dian)池充電(dian)(dian)器(qi)和周邊PCB板溫(wen)度升至非常高(gao)，盡(jin)管具備(bei)關(guan)閉(bi)(bi)“保(bao)(bao)護”功能(neng)，但(dan)必須(xu)對(dui)應用(yong)進(jin)行仔細設(she)計以避免到達熱(re)(re)關(guan)閉(bi)(bi)溫(wen)度。LTC1733通過自(zi)動均衡充電(dian)(dian)電(dian)(dian)流(liu)、散熱(re)(re)和工(gong)作溫(wen)度，可使設(she)計得(de)到簡(jian)化。

　　為進一(yi)步(bu)改進LTC1733的(de)熱調節性能(neng)，它采(cai)用了(le)熱增強型MSOP封裝。其占(zhan)用板面(mian)積可做到小于(yu)(yu)72 mm2，室(shi)溫功耗(hao)2W。這相(xiang)當于(yu)(yu)用5V輸入電(dian)(dian)(dian)源實現最(zui)大充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流1.5A。這里假定(ding)鋰(li)離子(zi)電(dian)(dian)(dian)池(chi)在充(chong)(chong)電(dian)(dian)(dian)大部分時間(jian)里處于(yu)(yu)(3.7V狀(zhuang)態。實際上，由于(yu)(yu)典型的(de)鋰(li)離子(zi)電(dian)(dian)(dian)池(chi)在充(chong)(chong)電(dian)(dian)(dian)開始幾分鐘內便升到3.8V以(yi)上，因此這一(yi)假定(ding)有些(xie)保守。LTC1733的(de)這一(yi)獨特熱特性和7%的(de)設定(ding)充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流精(jing)度，使單電(dian)(dian)(dian)池(chi)鋰(li)離子(zi)電(dian)(dian)(dian)池(chi)系統的(de)充(chong)(chong)電(dian)(dian)(dian)過程非常迅速和精(jing)確。

　　PROG電流監控器
　　在(zai)恒流(liu)模式下，PROG腳(jiao)的(de)電壓總為1.5V，指(zhi)示設定的(de)充(chong)電電流(liu)從BAT腳(jiao)流(liu)出。在(zai)恒溫(wen)或恒壓模式下，BAT腳(jiao)的(de)電流(liu)有所下降(jiang)。PROG腳(jiao)與三個開漏狀(zhuang)態輸出(ACPR、CHRG和(he) FAULT)時刻通告(gao)用戶(hu)LTC1733到底在(zai)做什(shen)么。

　　NTC熱敏電阻
　　除(chu)了可編程定(ding)時器(qi)和低(di)的(de)(de)電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)限定(ding)條件外，LTC1733在推薦給電(dian)(dian)(dian)池(chi)制(zhi)造商的(de)(de)安全性特性列表中(zhong)還增加了充電(dian)(dian)(dian)時的(de)(de)溫(wen)(wen)度(du)限定(ding)。電(dian)(dian)(dian)池(chi)溫(wen)(wen)度(du)通過緊貼(tie)電(dian)(dian)(dian)池(chi)組放置一只(zhi)負(fu)溫(wen)(wen)度(du)系(xi)數(NTC)熱(re)敏電(dian)(dian)(dian)阻來測定(ding)。借助IC中(zhong)的(de)(de)內(nei)(nei)部(bu)溫(wen)(wen)度(du)限制(zhi)電(dian)(dian)(dian)路，LTC1733在電(dian)(dian)(dian)池(chi)溫(wen)(wen)度(du)降到(dao)0(C以(yi)(yi)下或升到(dao)50(C以(yi)(yi)上(shang)時，可臨(lin)時停住內(nei)(nei)部(bu)定(ding)時器(qi)并停止充電(dian)(dian)(dian)。實施這一功(gong)能，選用RHOT的(de)(de)電(dian)(dian)(dian)阻值應與50(C下所用熱(re)敏電(dian)(dian)(dian)阻的(de)(de)阻值相同。這樣(yang)將可以(yi)(yi)確保內(nei)(nei)部(bu)比(bi)較器(qi)的(de)(de)1/2VCC摔點(trip point)與NTC的(de)(de)50(C溫(wen)(wen)度(du)相對應。

　　還有，選定的NTC熱敏電阻在0(C時的阻值應盡量接近50(C時阻值的7倍。7：1的冷熱NTC比率可確保內部比較器7/8VCC的摔點與NTC 0(C的溫度相對應。每個熱和冷比較器都有約2(C的滯后以防摔點的振蕩。另外，NTC可以不使用任何外部元件，只簡單地通過將NTC腳接地就可使其功能失效。
 
　　結論
　　LTC1733是一種全功能的獨立鋰離子電池充電器。其結構極為簡單，只需要三個外部元件，就可安全精確地將高容量電池快充至1.5A的充電電流。在體現安全性及狀態特性方面，可加上一只NTC熱敏電阻和幾個LED。目前許多用鋰離子電池作供電電源的設備可采用這種類型的充電器，如數字靜態照相機(DSC)、個人數字助理(PDA)、蜂窩電話、MP3播放機以及GPS系統等。
 
　　值得注意的是，對上述諸多產品中有許多產品，有一種需求越來越強烈。就是通過ＵＳＢ接口插入一個主設備時，電池正在充電。盡管LTC1733可用于這類充電應用，但USB端口的可獲電流量有限，或500mA 或 100mA，依連接外設的數量而定。而在這些應用中LTC1733存在的一個缺陷是關閉模式下的靜態電流為0.9mA。這是一個難點，因為USB規范定義了一種暫停(SUSPEND)模式，即在USB+5V的情況下，漏電電流必須低于500(A。不過，凌特技術公司還有LTC4053，一種與USB兼容的鋰離子電池充電器。它在關閉模式下源電流僅為25(A。所以，當外設在USB請求暫停模式時，將中LTC4053，以滿足所要求的漏電電流限制。
 
    凌特公司（Linear Technology）推出獨立的開關模式鋰離子電池充電器 LTC4002，工作電源電壓可高達 24V，從而不需要 9V 和更高電壓墻上適配器所需的輸入瞬變保護。另外，器件的 4.7V 低輸入電源以及低壓差工作特性保證了 4.2V 鋰離子電池可從 5V 墻上適配器持續充電。為了實現安全自主的充電控制，LTC4002 還包括自動關機、電池預查驗、電池溫度檢測、充電結束指示以及一個充電 3 小時終止定時器等特性。
 
　　與遲滯拓樸結構充電器相比，LTC4002 恒定的 500kHz 工作頻率和電流模式結構允許使用更小的電感器和電容器。由于 100mV 的低檢測電壓，所以很容易達到超過86%。這種獨立的充電器有兩種封裝，3mm×3mm DFN 和 8 引線 SO。LTC4002 可應用于手持式儀表和通信裝置、充電座、便攜式計算機以及電池備份系統。
 
　　LTC4002 是一種高效率電流模式 PWM 控制器，開關頻率為 500kHz。它驅動一個外部 P 溝道 MOSFET，以最高 87% 的效率提供高達 2A 的充電電流。這種集成電路的恒定開關頻率將噪聲和濾波需求減至最低。配合使用各類輸出電容器（包括低 ESR 陶瓷電容器），LTC4002 都是穩定的。一個內部比較器檢測充電結束電流，而集成的定時器設定總充電時間，并在三小時后終止充電。LTC4002 自動進入休眠模式，使電池耗用電流降至 10uA。而且，當電池電壓降至 4.05V 以下時，這種集成電路還能自動開始充電
。
　　LTC4002 的工作溫度定在 －40°C 到 85°C。以 1000 片為單位批量購買，每片起價為 1.95美元。
 
　　LTC4002 性(xing)能概要：