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)越來越普遍(bian)，而(er)配用(yong)的(de)充(chong)(chong)電(dian)(dian)器無論(lun)是(shi)(shi)市售的(de)15元手機充(chong)(chong)電(dian)(dian)器還(huan)(huan)是(shi)(shi)較高(gao)(gao)檔的(de)DC/DV兼(jian)容(rong)充(chong)(chong)電(dian)(dian)器，絕大部分是(shi)(shi)采(cai)用(yong)LM324組(zu)成的(de)充(chong)(chong)電(dian)(dian)電(dian)(dian)壓檢測和控(kong)制線路，這些線路無論(lun)從控(kong)制精度還(huan)(huan)是(shi)(shi)功能(neng)方面都不能(neng)滿足(zu)鋰電(dian)(dian)池充(chong)(chong)電(dian)(dian)特性的(de)要(yao)求，直接導(dao)致電(dian)(dian)池充(chong)(chong)不滿，電(dian)(dian)池壽命減(jian)短(duan)以及越來越多(duo)的(de)電(dian)(dian)池損壞、爆炸(zha)等案例發生。而(er)如果采(cai)用(yong)國外專用(yong)IC來設(she)計，則其極(ji)其高(gao)(gao)昂的(de)成本實(shi)在(zai)令人無法接受。

     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，在大致相(xiang)當的總體(ti)成(cheng)本(ben)下(xia)提供(gong)了遠遠超過(guo)LM324方案(an)的性能，具(ju)有極高的新穎性和市場前景。

PT7M7433T是上(shang)海(hai)百利通公司最新設計的(de)極高精度的(de)一系列電壓檢(jian)測(ce)(ce)器的(de)其中(zhong)一款(kuan)，其檢(jian)測(ce)(ce)精度在0-Vcc （5.5V）范圍內小于1mV，而且其批(pi)量(liang)IC的(de)檢(jian)測(ce)(ce)值偏(pian)差<±2.5%，這樣完全保證了批(pi)量(liang)產品的(de)性(xing)能(neng)一致性(xing)和極高的(de)總體性(xing)能(neng)，我們利用(yong)其配(pei)合少量(liang)外部電路即可組成相當簡(jian)單的(de)鋰(li)電池充電線路。

該IC的內部框(kuang)圖(tu)(tu)和簡單介紹如下：（圖(tu)(tu)一）

IC內(nei)含一個(ge)高(gao)精度的(de)(de)615mV基準電壓(ya)源、兩個(ge)比(bi)較器(qi)、一個(ge)RS觸發器(qi)和(he)(he)其(qi)它(ta)一些(xie)邏輯電路，其(qi)大致功能是：VCC電壓(ya)或其(qi)它(ta)待(dai)(dai)檢測電壓(ya)通過R1-R3組成的(de)(de)分壓(ya)網絡接在IC的(de)(de)LTHIN /HTHIN檢測引(yin)腳，當待(dai)(dai)測電壓(ya)下降導(dao)致LTHIN引(yin)腳低于(yu)615mV時(shi)(shi)，輸出腳LBO輸出低電平(ping)，而如果待(dai)(dai)測電壓(ya)上升(sheng)導(dao)致HTHIN引(yin)腳高(gao)于(yu)615 mV時(shi)(shi)，經過內(nei)部邏輯判(pan)斷和(he)(he)簡單延時(shi)(shi)后，輸出腳LBO輸出高(gao)電平(ping)。

利用這個IC裝制的(de)充電(dian)器電(dian)路如下（圖二）

其工作流(liu)程大(da)致(zhi)是：當(dang)接上Li+電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)和供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源時(shi)，IC通(tong)(tong)過(guo)(guo)(guo)R1/R2/R3組成(cheng)的(de)(de)(de)(de)網絡檢測電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓，如果電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓低(di)于(yu)3.3V（由(you)R1-R3的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻值(zhi)決定），或(huo)者按(an)下按(an)制SW1，此時(shi)IC3腳(jiao)(jiao)(jiao)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓低(di)于(yu)615mV，則IC4腳(jiao)(jiao)(jiao)輸(shu)出低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平，通(tong)(tong)過(guo)(guo)(guo)R5/D2拉低(di)Q1的(de)(de)(de)(de)柵(zha)極(ji)使(shi)之導(dao)通(tong)(tong)，從(cong)而(er)通(tong)(tong)過(guo)(guo)(guo)Q1/R9/D1給(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)進行大(da)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓一(yi)(yi)路上升直至超過(guo)(guo)(guo)4.20V,此時(shi)IC的(de)(de)(de)(de)1腳(jiao)(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓高過(guo)(guo)(guo)615mV,IC內部經簡單判斷和延時(shi)，令4腳(jiao)(jiao)(jiao)輸(shu)出高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平，從(cong)而(er)關閉大(da)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)通(tong)(tong)道，但(dan)是4腳(jiao)(jiao)(jiao)的(de)(de)(de)(de)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平同(tong)時(shi)給(gei)R7/C2的(de)(de)(de)(de)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)回路供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，令到Q3的(de)(de)(de)(de)柵(zha)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓慢慢升高，并給(gei)R8提供(gong)(gong)通(tong)(tong)路導(dao)致(zhi)Q2導(dao)通(tong)(tong)，通(tong)(tong)過(guo)(guo)(guo)R10給(gei)Q1提供(gong)(gong)一(yi)(yi)個(ge)較(jiao)弱的(de)(de)(de)(de)導(dao)通(tong)(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)，使(shi)之微(wei)微(wei)導(dao)通(tong)(tong)，從(cong)而(er)為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)提供(gong)(gong)一(yi)(yi)個(ge)較(jiao)少的(de)(de)(de)(de)補充(chong)(chong)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。按(an)照(zhao)圖(tu)中所示元件參數將(jiang)于(yu)大(da)約(yue)十分(fen)鐘后(hou)，由(you)于(yu)C2的(de)(de)(de)(de)不斷充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，其端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓即Q3的(de)(de)(de)(de)柵(zha)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓不斷上升直至使(shi)Q3導(dao)通(tong)(tong)，從(cong)而(er)關閉Q2，令到整個(ge)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)(guo)(guo)程結(jie)束(shu)。

上面的(de)(de)方(fang)(fang)(fang)案還(huan)存在一些不(bu)足之處，例如檢(jian)測精度由外接電(dian)(dian)(dian)阻R1/R2/R3的(de)(de)精度決定，對于過放(fang)電(dian)(dian)(dian)的(de)(de)電(dian)(dian)(dian)池（電(dian)(dian)(dian)池端(duan)電(dian)(dian)(dian)壓低(di)于2.8V）沒有一個小電(dian)(dian)(dian)流預充的(de)(de)過程，另(ling)外該方(fang)(fang)(fang)案的(de)(de)10分鐘補充充電(dian)(dian)(dian)時間對于較大容量(liang)的(de)(de)電(dian)(dian)(dian)池來(lai)說(shuo)不(bu)是太足夠，因此針(zhen)對上述不(bu)足之處，我們還(huan)提供一個成本稍高一點，性能更加完善(shan)的(de)(de)方(fang)(fang)(fang)案：（圖三）

乍看之下，這個方案采(cai)用了三個IC，可是(shi)(shi)(shi)U1和U2是(shi)(shi)(shi)采(cai)用的(de)(de)SOT-23或者TO-92封裝，就好(hao)像普通三極(ji)管一樣，其(qi)價格也就是(shi)(shi)(shi)2-3個三極(ji)管的(de)(de)價格，而U3（PT8A2513NE）也是(shi)(shi)(shi)采(cai)用的(de)(de)TO-94封裝，外形(xing)和三極(ji)管很相似，價錢也相當便宜，不(bu)過，這個電(dian)(dian)路(lu)可以(yi)實(shi)現智(zhi)能判斷電(dian)(dian)池是(shi)(shi)(shi)否(fou)(fou)過放電(dian)(dian)，決定是(shi)(shi)(shi)否(fou)(fou)在開始(shi)充(chong)(chong)電(dian)(dian)時采(cai)用小(xiao)電(dian)(dian)流預充(chong)(chong)，另外，采(cai)用U3后也將充(chong)(chong)電(dian)(dian)后期的(de)(de)補充(chong)(chong)充(chong)(chong)電(dian)(dian)過程延(yan)長到大約一個小(xiao)時！

首先(xian)讓我(wo)們(men)介紹一下(xia)該電(dian)路中幾個IC的功能：

（圖四）是(shi)U1/U2的(de)內部(bu)(bu)框圖，這(zhe)兩(liang)個IC只是(shi)內部(bu)(bu)電阻R1/R2的(de)數值(zhi)不(bu)(bu)同(tong)而已，它們(men)的(de)功能也很簡單：當Vcc低于IC的(de)設定值(zhi)時（根(gen)據IC編號(hao)不(bu)(bu)同(tong)，內部(bu)(bu)R3/R4阻值(zhi)也不(bu)(bu)同(tong)從而導致檢測電壓(ya)值(zhi)不(bu)(bu)同(tong)，對于PT7M6128指的(de)是(shi)2.80V），RST引腳輸出(chu)低電平，反之當Vcc 高于1.05倍標(biao)稱值(zhi)時（例(li)如(ru)對于PT7M6140，此數值(zhi)為1.05x4.0 =4.20V）則RST引腳輸出(chu)高電平。

上(shang)面電(dian)路的(de)另(ling)外一(yi)(yi)個(ge)(ge)IC（PT8A25 13）則是(shi)一(yi)(yi)個(ge)(ge)極(ji)簡(jian)單(dan)卻極(ji)穩定的(de)延時IC，其(qi)延時時間僅僅取決于 OSC腳(jiao)的(de)頻(pin)(pin)率。事實上(shang)該IC就是(shi)將OSC震(zhen)蕩頻(pin)(pin)率進行32768次(ci)分頻(pin)(pin)后(hou)用(yong)來控制輸出(chu)的(de)。之(zhi)所以采用(yong)這個(ge)(ge)電(dian)路而不采用(yong)LM555或(huo)者CD4060等通用(yong)IC的(de)原因就是(shi)因為(wei)它(ta)相對而言定時精度更(geng)(geng)高(gao)（其(qi)它(ta)IC不分頻(pin)(pin)），定時時間更(geng)(geng)長（可(ke)達數小時）。并且電(dian)路更(geng)(geng)加簡(jian)單(dan)，采用(yong)TO-94或(huo)SOT-23-4封裝，就像(xiang)一(yi)(yi)個(ge)(ge)三極(ji)管一(yi)(yi)樣。而價錢也跟(gen)CD4060差(cha)不多(duo)(duo)，使(shi)用(yong)效果可(ke)就好的(de)太多(duo)(duo)了。

至此(ci)大(da)家想必也(ye)(ye)大(da)致了解了圖三的(de)(de)工作流(liu)(liu)程了：接上電(dian)(dian)(dian)(dian)(dian)池(chi)和(he)充(chong)電(dian)(dian)(dian)(dian)(dian)器，如果電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓低于2.8V，則(ze)U1輸(shu)(shu)出(chu)(chu)為(wei)低（U2輸(shu)(shu)出(chu)(chu)也(ye)(ye)是低），這樣R3和(he)R4的(de)(de)回(hui)路都(dou)不(bu)通，只(zhi)有R2回(hui)路導通，給(gei)Q1提供微弱的(de)(de)導通，使(shi)(shi)之輸(shu)(shu)出(chu)(chu)約數毫安的(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)給(gei)電(dian)(dian)(dian)(dian)(dian)池(chi)進行預充(chong)電(dian)(dian)(dian)(dian)(dian)，當(dang)(dang)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓上升到(dao)超過2.94V（1.05X2.8）時(shi)或(huo)者(zhe)剛接上電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓就(jiu)超過2.94V時(shi)，U1輸(shu)(shu)出(chu)(chu)高電(dian)(dian)(dian)(dian)(dian)平而(er)(er)(er)U2繼續輸(shu)(shu)出(chu)(chu)低電(dian)(dian)(dian)(dian)(dian)平（電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓還沒達到(dao)4.2V J），這時(shi)R2通路截止而(er)(er)(er)R3通路導通（因為(wei)Q4導通且其源極電(dian)(dian)(dian)(dian)(dian)平為(wei)低-因U1輸(shu)(shu)出(chu)(chu)拉低），從而(er)(er)(er)由較(jiao)小(xiao)阻值的(de)(de)R3令Q1完(wan)全導通，提供一個數百毫安的(de)(de)大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)恒流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)，而(er)(er)(er)當(dang)(dang)這個恒流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)過程慢慢令到(dao)被充(chong)電(dian)(dian)(dian)(dian)(dian)的(de)(de)Li+電(dian)(dian)(dian)(dian)(dian)池(chi)端(duan)電(dian)(dian)(dian)(dian)(dian)壓上升到(dao)4.2V時(shi)，U2也(ye)(ye)輸(shu)(shu)出(chu)(chu)高電(dian)(dian)(dian)(dian)(dian)平從而(er)(er)(er)關(guan)閉Q4,但是它同(tong)時(shi)也(ye)(ye)給(gei)U3提供了電(dian)(dian)(dian)(dian)(dian)源導致U3開始工作，這樣U3觸發(fa)Q3使(shi)(shi)R4導通提供一個很小(xiao)的(de)(de)補充(chong)充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，直至U3達到(dao)定時(shi)時(shi)間(jian)從而(er)(er)(er)關(guan)閉Q3，這時(shi)整個充(chong)電(dian)(dian)(dian)(dian)(dian)過程才(cai)完(wan)全結束。

相(xiang)比而言，第二個(ge)方案增加了前期智能(neng)判斷(duan)電(dian)池狀態和自動預充電(dian)過程(cheng)，以及(ji)延長了末尾的(de)補(bu)充充電(dian)過程(cheng)的(de)時間(jian)，各個(ge)階段的(de)充電(dian)電(dian)流可調并且補(bu)充充電(dian)時間(jian)可調（數分鐘至數小時），因此該方案對(dui)鋰電(dian)池充電(dian)具有更好的(de)精(jing)確性和安(an)全性，加上價錢便宜，功(gong)能(neng)也比較完善(shan)，相(xiang)信很(hen)快會取(qu)代(dai)市(shi)面中低檔的(de)充電(dian)器特別是那些(xie)廉價的(de)手機電(dian)池充電(dian)器。