隨著手機、MP3、PMP、DC/DV等手持電子產品越來越大眾化，鋰金屬（Li）和鋰離子電池使用(yong)(yong)越來越普遍，而(er)配(pei)用(yong)(yong)的(de)(de)(de)充(chong)(chong)電(dian)器無(wu)論是(shi)市售(shou)的(de)(de)(de)15元手機(ji)充(chong)(chong)電(dian)器還是(shi)較高檔的(de)(de)(de)DC/DV兼容充(chong)(chong)電(dian)器，絕(jue)大部(bu)分(fen)是(shi)采用(yong)(yong)LM324組(zu)成的(de)(de)(de)充(chong)(chong)電(dian)電(dian)壓(ya)檢測和控制線路(lu)，這(zhe)些線路(lu)無(wu)論從(cong)控制精度(du)還是(shi)功能方面(mian)都不(bu)(bu)能滿足鋰電(dian)池(chi)充(chong)(chong)電(dian)特(te)性的(de)(de)(de)要(yao)求(qiu)，直接導(dao)致電(dian)池(chi)充(chong)(chong)不(bu)(bu)滿，電(dian)池(chi)壽命減短(duan)以及(ji)越來越多(duo)的(de)(de)(de)電(dian)池(chi)損壞、爆炸(zha)等案(an)例(li)發生。而(er)如果采用(yong)(yong)國外專(zhuan)用(yong)(yong)IC來設計，則其(qi)極其(qi)高昂的(de)(de)(de)成本實在令(ling)人無(wu)法接受(shou)。

     有鑒于此，筆者在此介紹兩款由國產新型IC組成的鋰電池充電器，在(zai)大致相當的(de)總(zong)體成本下提供了(le)遠(yuan)遠(yuan)超過LM324方案的(de)性(xing)能(neng)，具有極高(gao)的(de)新穎(ying)性(xing)和市場(chang)前景。

PT7M7433T是(shi)上海百利通公司最新設(she)計的(de)(de)(de)(de)極高精度(du)的(de)(de)(de)(de)一系(xi)列電壓檢(jian)(jian)測器的(de)(de)(de)(de)其中一款，其檢(jian)(jian)測精度(du)在0-Vcc （5.5V）范(fan)圍內小于1mV，而(er)且其批(pi)量(liang)(liang)IC的(de)(de)(de)(de)檢(jian)(jian)測值偏(pian)差(cha)<±2.5%，這樣完全保證(zheng)了(le)批(pi)量(liang)(liang)產品(pin)的(de)(de)(de)(de)性(xing)(xing)能一致性(xing)(xing)和極高的(de)(de)(de)(de)總體性(xing)(xing)能，我們(men)利用其配(pei)合(he)少量(liang)(liang)外部電路即可組成相當(dang)簡(jian)單的(de)(de)(de)(de)鋰電池充電線路。

該(gai)IC的內部框圖和簡單介紹(shao)如下：（圖一(yi)）

IC內(nei)(nei)含(han)一個(ge)高(gao)精(jing)度(du)的(de)615mV基準電(dian)壓(ya)(ya)源、兩個(ge)比較器(qi)、一個(ge)RS觸發器(qi)和(he)其它一些邏輯電(dian)路，其大(da)致功(gong)能是：VCC電(dian)壓(ya)(ya)或其它待(dai)(dai)檢測(ce)電(dian)壓(ya)(ya)通過(guo)R1-R3組成(cheng)的(de)分壓(ya)(ya)網絡(luo)接在IC的(de)LTHIN /HTHIN檢測(ce)引(yin)腳(jiao)，當待(dai)(dai)測(ce)電(dian)壓(ya)(ya)下(xia)降導致LTHIN引(yin)腳(jiao)低于615mV時(shi)，輸出(chu)腳(jiao)LBO輸出(chu)低電(dian)平(ping)，而如果待(dai)(dai)測(ce)電(dian)壓(ya)(ya)上(shang)升(sheng)導致HTHIN引(yin)腳(jiao)高(gao)于615 mV時(shi)，經(jing)過(guo)內(nei)(nei)部邏輯判(pan)斷和(he)簡單延時(shi)后，輸出(chu)腳(jiao)LBO輸出(chu)高(gao)電(dian)平(ping)。

利用這(zhe)個(ge)IC裝制的充(chong)電器電路如(ru)下（圖二(er)）

其工作流(liu)(liu)程(cheng)大(da)致是：當接(jie)上(shang)Li+電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)和供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)源時(shi)，IC通(tong)(tong)(tong)(tong)(tong)過(guo)(guo)(guo)R1/R2/R3組成的(de)網(wang)絡檢測電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，如果電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)低于3.3V（由R1-R3的(de)電(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)值決定），或者按(an)下按(an)制SW1，此時(shi)IC3腳的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)低于615mV，則IC4腳輸出低電(dian)(dian)(dian)(dian)(dian)(dian)平，通(tong)(tong)(tong)(tong)(tong)過(guo)(guo)(guo)R5/D2拉(la)低Q1的(de)柵(zha)(zha)極使之導通(tong)(tong)(tong)(tong)(tong)，從而(er)通(tong)(tong)(tong)(tong)(tong)過(guo)(guo)(guo)Q1/R9/D1給電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)進行大(da)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，當電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)一(yi)路上(shang)升(sheng)直至超過(guo)(guo)(guo)4.20V,此時(shi)IC的(de)1腳電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)高(gao)過(guo)(guo)(guo)615mV,IC內部經簡單判斷(duan)和延時(shi)，令(ling)4腳輸出高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)平，從而(er)關閉(bi)大(da)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)通(tong)(tong)(tong)(tong)(tong)道(dao)，但是4腳的(de)高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)平同(tong)時(shi)給R7/C2的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)回路供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)，令(ling)到Q3的(de)柵(zha)(zha)極電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)慢慢升(sheng)高(gao)，并(bing)給R8提供(gong)通(tong)(tong)(tong)(tong)(tong)路導致Q2導通(tong)(tong)(tong)(tong)(tong)，通(tong)(tong)(tong)(tong)(tong)過(guo)(guo)(guo)R10給Q1提供(gong)一(yi)個(ge)(ge)較弱的(de)導通(tong)(tong)(tong)(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，使之微(wei)微(wei)導通(tong)(tong)(tong)(tong)(tong)，從而(er)為電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)提供(gong)一(yi)個(ge)(ge)較少的(de)補充(chong)(chong)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)。按(an)照圖中所(suo)示元件參數將于大(da)約十分鐘后，由于C2的(de)不(bu)斷(duan)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，其端電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)即Q3的(de)柵(zha)(zha)極電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)不(bu)斷(duan)上(shang)升(sheng)直至使Q3導通(tong)(tong)(tong)(tong)(tong)，從而(er)關閉(bi)Q2，令(ling)到整個(ge)(ge)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過(guo)(guo)(guo)程(cheng)結束。

上面的(de)(de)方(fang)(fang)案(an)還存在一些不(bu)足(zu)之(zhi)處，例如檢測(ce)精度(du)(du)由外接電(dian)(dian)阻(zu)R1/R2/R3的(de)(de)精度(du)(du)決(jue)定，對(dui)(dui)于過放電(dian)(dian)的(de)(de)電(dian)(dian)池（電(dian)(dian)池端電(dian)(dian)壓低(di)于2.8V）沒有一個(ge)小電(dian)(dian)流預充(chong)的(de)(de)過程，另外該方(fang)(fang)案(an)的(de)(de)10分(fen)鐘補充(chong)充(chong)電(dian)(dian)時間對(dui)(dui)于較(jiao)大容量的(de)(de)電(dian)(dian)池來說不(bu)是太足(zu)夠，因此針對(dui)(dui)上述(shu)不(bu)足(zu)之(zhi)處，我們還提供一個(ge)成本稍高一點，性(xing)能更加完(wan)善的(de)(de)方(fang)(fang)案(an)：（圖三）

乍(zha)看(kan)之(zhi)下，這個方案采(cai)(cai)用了三(san)(san)個IC，可是(shi)U1和(he)U2是(shi)采(cai)(cai)用的SOT-23或者(zhe)TO-92封(feng)裝，就好像(xiang)普通三(san)(san)極管一樣，其價格也就是(shi)2-3個三(san)(san)極管的價格，而U3（PT8A2513NE）也是(shi)采(cai)(cai)用的TO-94封(feng)裝，外形(xing)和(he)三(san)(san)極管很相(xiang)似，價錢(qian)也相(xiang)當便(bian)宜，不過(guo)，這個電(dian)路可以實現智能判(pan)斷(duan)電(dian)池(chi)是(shi)否過(guo)放電(dian)，決定(ding)是(shi)否在開始充(chong)電(dian)時(shi)采(cai)(cai)用小電(dian)流預充(chong)，另外，采(cai)(cai)用U3后也將充(chong)電(dian)后期(qi)的補充(chong)充(chong)電(dian)過(guo)程延(yan)長到大約(yue)一個小時(shi)！

首(shou)先讓我們介紹(shao)一下(xia)該電路中(zhong)幾個IC的功(gong)能：

（圖(tu)四）是U1/U2的內部(bu)框圖(tu)，這兩(liang)個IC只(zhi)是內部(bu)電(dian)阻R1/R2的數值(zhi)不(bu)同(tong)(tong)而(er)已(yi)，它(ta)們(men)的功能也很簡單：當Vcc低(di)于(yu)IC的設(she)定值(zhi)時（根(gen)據(ju)IC編號不(bu)同(tong)(tong)，內部(bu)R3/R4阻值(zhi)也不(bu)同(tong)(tong)從而(er)導致檢測電(dian)壓值(zhi)不(bu)同(tong)(tong)，對于(yu)PT7M6128指的是2.80V），RST引腳輸(shu)出低(di)電(dian)平(ping)(ping)，反之當Vcc 高(gao)于(yu)1.05倍標(biao)稱值(zhi)時（例如對于(yu)PT7M6140，此(ci)數值(zhi)為1.05x4.0 =4.20V）則RST引腳輸(shu)出高(gao)電(dian)平(ping)(ping)。

上面電路(lu)的(de)另外一個IC（PT8A25 13）則(ze)是一個極(ji)簡單(dan)(dan)卻極(ji)穩定的(de)延(yan)時(shi)(shi)IC，其延(yan)時(shi)(shi)時(shi)(shi)間(jian)僅僅取決于(yu) OSC腳的(de)頻(pin)率(lv)(lv)。事實上該IC就(jiu)是將(jiang)OSC震蕩頻(pin)率(lv)(lv)進行32768次分(fen)頻(pin)后(hou)用(yong)來(lai)控(kong)制輸出的(de)。之所以(yi)采用(yong)這個電路(lu)而(er)(er)不采用(yong)LM555或者(zhe)CD4060等通用(yong)IC的(de)原因就(jiu)是因為它相對(dui)而(er)(er)言定時(shi)(shi)精度更高（其它IC不分(fen)頻(pin)），定時(shi)(shi)時(shi)(shi)間(jian)更長（可達(da)數小時(shi)(shi)）。并且電路(lu)更加簡單(dan)(dan)，采用(yong)TO-94或SOT-23-4封裝，就(jiu)像一個三極(ji)管一樣(yang)。而(er)(er)價錢也(ye)跟CD4060差不多(duo)，使(shi)用(yong)效果可就(jiu)好的(de)太多(duo)了。

至(zhi)此大家想必也(ye)大致(zhi)了解了圖(tu)三(san)的(de)(de)工作流(liu)程(cheng)了：接上電(dian)(dian)(dian)(dian)池(chi)(chi)和(he)充(chong)(chong)電(dian)(dian)(dian)(dian)器，如果電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)低(di)(di)于2.8V，則(ze)U1輸(shu)(shu)出(chu)(chu)(chu)(chu)為低(di)(di)（U2輸(shu)(shu)出(chu)(chu)(chu)(chu)也(ye)是低(di)(di)），這(zhe)樣(yang)R3和(he)R4的(de)(de)回(hui)路(lu)都不通(tong)，只有R2回(hui)路(lu)導(dao)通(tong)，給(gei)Q1提供微弱的(de)(de)導(dao)通(tong)，使之輸(shu)(shu)出(chu)(chu)(chu)(chu)約數毫安(an)的(de)(de)電(dian)(dian)(dian)(dian)流(liu)給(gei)電(dian)(dian)(dian)(dian)池(chi)(chi)進行(xing)預充(chong)(chong)電(dian)(dian)(dian)(dian)，當電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)上升到超過(guo)2.94V（1.05X2.8）時(shi)(shi)(shi)或者剛接上電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)就(jiu)超過(guo)2.94V時(shi)(shi)(shi)，U1輸(shu)(shu)出(chu)(chu)(chu)(chu)高(gao)電(dian)(dian)(dian)(dian)平而(er)(er)U2繼續輸(shu)(shu)出(chu)(chu)(chu)(chu)低(di)(di)電(dian)(dian)(dian)(dian)平（電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)還(huan)沒達(da)(da)到4.2V J），這(zhe)時(shi)(shi)(shi)R2通(tong)路(lu)截止而(er)(er)R3通(tong)路(lu)導(dao)通(tong)（因為Q4導(dao)通(tong)且其源極電(dian)(dian)(dian)(dian)平為低(di)(di)-因U1輸(shu)(shu)出(chu)(chu)(chu)(chu)拉(la)低(di)(di)），從而(er)(er)由較小(xiao)阻(zu)值的(de)(de)R3令(ling)Q1完(wan)全導(dao)通(tong)，提供一個數百(bai)毫安(an)的(de)(de)大電(dian)(dian)(dian)(dian)流(liu)恒流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)，而(er)(er)當這(zhe)個恒流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)過(guo)程(cheng)慢慢令(ling)到被充(chong)(chong)電(dian)(dian)(dian)(dian)的(de)(de)Li+電(dian)(dian)(dian)(dian)池(chi)(chi)端電(dian)(dian)(dian)(dian)壓(ya)上升到4.2V時(shi)(shi)(shi)，U2也(ye)輸(shu)(shu)出(chu)(chu)(chu)(chu)高(gao)電(dian)(dian)(dian)(dian)平從而(er)(er)關閉Q4,但是它(ta)同時(shi)(shi)(shi)也(ye)給(gei)U3提供了電(dian)(dian)(dian)(dian)源導(dao)致(zhi)U3開始工作，這(zhe)樣(yang)U3觸發Q3使R4導(dao)通(tong)提供一個很小(xiao)的(de)(de)補充(chong)(chong)充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)，直(zhi)至(zhi)U3達(da)(da)到定時(shi)(shi)(shi)時(shi)(shi)(shi)間(jian)從而(er)(er)關閉Q3，這(zhe)時(shi)(shi)(shi)整個充(chong)(chong)電(dian)(dian)(dian)(dian)過(guo)程(cheng)才完(wan)全結束(shu)。

相(xiang)比(bi)而言，第二個方案(an)增加了(le)前(qian)期智能判斷(duan)電(dian)池(chi)狀態和(he)自動預充(chong)電(dian)過程(cheng)，以及延長了(le)末尾的(de)補充(chong)充(chong)電(dian)過程(cheng)的(de)時間，各個階段(duan)的(de)充(chong)電(dian)電(dian)流可調并且(qie)補充(chong)充(chong)電(dian)時間可調（數(shu)分鐘至數(shu)小(xiao)時），因(yin)此(ci)該方案(an)對(dui)鋰電(dian)池(chi)充(chong)電(dian)具有更好的(de)精確性和(he)安全性，加上價錢便宜，功能也比(bi)較完善，相(xiang)信(xin)很快會取代市面中低檔的(de)充(chong)電(dian)器(qi)特別是那些廉價的(de)手機電(dian)池(chi)充(chong)電(dian)器(qi)。