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）和鋰離子電池使用越(yue)來越(yue)普(pu)遍，而配用的(de)(de)(de)(de)(de)充電(dian)(dian)器(qi)無(wu)(wu)論(lun)是(shi)(shi)市售的(de)(de)(de)(de)(de)15元手機充電(dian)(dian)器(qi)還(huan)是(shi)(shi)較高檔的(de)(de)(de)(de)(de)DC/DV兼容充電(dian)(dian)器(qi)，絕(jue)大部分是(shi)(shi)采(cai)用LM324組(zu)成(cheng)的(de)(de)(de)(de)(de)充電(dian)(dian)電(dian)(dian)壓(ya)檢測和控制線路，這些線路無(wu)(wu)論(lun)從控制精度還(huan)是(shi)(shi)功能方面都不能滿足鋰電(dian)(dian)池充電(dian)(dian)特性的(de)(de)(de)(de)(de)要求，直接(jie)導致(zhi)電(dian)(dian)池充不滿，電(dian)(dian)池壽命減(jian)短以(yi)及越(yue)來越(yue)多(duo)的(de)(de)(de)(de)(de)電(dian)(dian)池損壞、爆炸等案例發生。而如果采(cai)用國外專用IC來設計，則其極(ji)其高昂的(de)(de)(de)(de)(de)成(cheng)本實在令人無(wu)(wu)法(fa)接(jie)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(dang)的總體(ti)成本下(xia)提供了遠遠超過LM324方案的性能(neng)，具有(you)極(ji)高(gao)的新穎性和(he)市場前景。

PT7M7433T是(shi)上海(hai)百利通公司最新設計的(de)極高(gao)精(jing)度(du)的(de)一(yi)系(xi)列電(dian)壓檢測(ce)器的(de)其中一(yi)款(kuan)，其檢測(ce)精(jing)度(du)在0-Vcc （5.5V）范(fan)圍(wei)內小(xiao)于(yu)1mV，而且其批量IC的(de)檢測(ce)值(zhi)偏差<±2.5%，這樣完全保(bao)證了批量產(chan)品的(de)性(xing)能一(yi)致性(xing)和(he)極高(gao)的(de)總體性(xing)能，我們利用(yong)其配合少量外部(bu)電(dian)路(lu)即可組成相當(dang)簡單的(de)鋰(li)電(dian)池(chi)充電(dian)線路(lu)。

該IC的內部框圖和簡單介紹如(ru)下：（圖一）

IC內含一(yi)個(ge)高精度的615mV基準(zhun)電(dian)壓源、兩個(ge)比較器、一(yi)個(ge)RS觸發器和(he)其(qi)它(ta)一(yi)些邏輯電(dian)路，其(qi)大致功能是(shi)：VCC電(dian)壓或其(qi)它(ta)待(dai)檢測(ce)(ce)電(dian)壓通過(guo)R1-R3組成的分壓網絡(luo)接在IC的LTHIN /HTHIN檢測(ce)(ce)引(yin)腳，當待(dai)測(ce)(ce)電(dian)壓下降導致LTHIN引(yin)腳低于(yu)615mV時，輸出(chu)(chu)腳LBO輸出(chu)(chu)低電(dian)平，而如果待(dai)測(ce)(ce)電(dian)壓上升導致HTHIN引(yin)腳高于(yu)615 mV時，經過(guo)內部邏輯判斷(duan)和(he)簡單延時后，輸出(chu)(chu)腳LBO輸出(chu)(chu)高電(dian)平。

利用這個IC裝制(zhi)的(de)充(chong)電器(qi)電路(lu)如下（圖二(er)）

其工(gong)作流(liu)程大致是：當接(jie)上Li+電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池和供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)時，IC通(tong)過(guo)R1/R2/R3組成的(de)網絡檢(jian)測電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，如果(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)低于3.3V（由R1-R3的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻值決定），或者按下(xia)按制(zhi)SW1，此時IC3腳(jiao)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)低于615mV，則IC4腳(jiao)輸(shu)出低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平，通(tong)過(guo)R5/D2拉(la)低Q1的(de)柵(zha)(zha)極(ji)使(shi)之導(dao)(dao)通(tong)，從而通(tong)過(guo)Q1/R9/D1給(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池進(jin)行大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)一路上升直(zhi)至(zhi)超過(guo)4.20V,此時IC的(de)1腳(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)高(gao)過(guo)615mV,IC內部經簡單判斷和延(yan)時，令(ling)4腳(jiao)輸(shu)出高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平，從而關(guan)閉大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)通(tong)道(dao)，但(dan)是4腳(jiao)的(de)高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平同時給(gei)R7/C2的(de)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)回路供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，令(ling)到Q3的(de)柵(zha)(zha)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)慢慢升高(gao)，并(bing)給(gei)R8提(ti)供(gong)(gong)通(tong)路導(dao)(dao)致Q2導(dao)(dao)通(tong)，通(tong)過(guo)R10給(gei)Q1提(ti)供(gong)(gong)一個(ge)較弱的(de)導(dao)(dao)通(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)，使(shi)之微(wei)微(wei)導(dao)(dao)通(tong)，從而為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池提(ti)供(gong)(gong)一個(ge)較少的(de)補充充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。按照圖中(zhong)所(suo)示元(yuan)件參(can)數將于大約(yue)十分鐘后，由于C2的(de)不(bu)斷充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，其端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)即Q3的(de)柵(zha)(zha)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)斷上升直(zhi)至(zhi)使(shi)Q3導(dao)(dao)通(tong)，從而關(guan)閉Q2，令(ling)到整個(ge)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程結束。

上(shang)面(mian)的(de)方案還存在一(yi)(yi)些不(bu)足之處，例如檢測精度由(you)外接電(dian)(dian)阻R1/R2/R3的(de)精度決(jue)定，對(dui)于(yu)過放電(dian)(dian)的(de)電(dian)(dian)池（電(dian)(dian)池端電(dian)(dian)壓低(di)于(yu)2.8V）沒有一(yi)(yi)個小電(dian)(dian)流(liu)預充(chong)的(de)過程，另外該方案的(de)10分鐘補充(chong)充(chong)電(dian)(dian)時間對(dui)于(yu)較大容量的(de)電(dian)(dian)池來(lai)說不(bu)是太足夠，因此針(zhen)對(dui)上(shang)述不(bu)足之處，我(wo)們還提供一(yi)(yi)個成(cheng)本稍(shao)高一(yi)(yi)點，性能(neng)更加(jia)完善的(de)方案：（圖三(san)）

乍看之(zhi)下，這個(ge)方案采用(yong)了三個(ge)IC，可(ke)是(shi)(shi)U1和U2是(shi)(shi)采用(yong)的(de)SOT-23或者TO-92封(feng)裝，就好像(xiang)普(pu)通三極管(guan)一樣(yang)，其(qi)價格也就是(shi)(shi)2-3個(ge)三極管(guan)的(de)價格，而U3（PT8A2513NE）也是(shi)(shi)采用(yong)的(de)TO-94封(feng)裝，外形和三極管(guan)很相(xiang)似(si)，價錢也相(xiang)當(dang)便宜，不過，這個(ge)電路可(ke)以實現智能判斷電池是(shi)(shi)否過放電，決定是(shi)(shi)否在(zai)開始充電時(shi)采用(yong)小(xiao)電流(liu)預充，另(ling)外，采用(yong)U3后(hou)也將充電后(hou)期(qi)的(de)補(bu)充充電過程(cheng)延長到(dao)大約一個(ge)小(xiao)時(shi)！

首先讓我們(men)介紹一下該電路(lu)中幾個(ge)IC的功能：

（圖四(si)）是U1/U2的(de)(de)內(nei)部框(kuang)圖，這兩個IC只是內(nei)部電(dian)阻R1/R2的(de)(de)數值(zhi)不同(tong)而(er)已，它們的(de)(de)功能也很簡(jian)單：當Vcc低于IC的(de)(de)設(she)定值(zhi)時（根據(ju)IC編號不同(tong)，內(nei)部R3/R4阻值(zhi)也不同(tong)從(cong)而(er)導致檢測電(dian)壓值(zhi)不同(tong)，對于PT7M6128指的(de)(de)是2.80V），RST引腳輸(shu)出低電(dian)平，反之(zhi)當Vcc 高(gao)于1.05倍標(biao)稱值(zhi)時（例如(ru)對于PT7M6140，此數值(zhi)為1.05x4.0 =4.20V）則RST引腳輸(shu)出高(gao)電(dian)平。

上面電(dian)(dian)路的(de)另(ling)外一(yi)個(ge)IC（PT8A25 13）則是一(yi)個(ge)極(ji)簡單(dan)卻極(ji)穩定的(de)延時(shi)(shi)IC，其延時(shi)(shi)時(shi)(shi)間僅僅取(qu)決于 OSC腳(jiao)的(de)頻率。事實上該IC就是將(jiang)OSC震蕩頻率進行32768次分頻后(hou)用(yong)來控制(zhi)輸出(chu)的(de)。之所以采(cai)用(yong)這個(ge)電(dian)(dian)路而不采(cai)用(yong)LM555或者CD4060等(deng)通(tong)用(yong)IC的(de)原(yuan)因就是因為它相對而言(yan)定時(shi)(shi)精度更(geng)高（其它IC不分頻），定時(shi)(shi)時(shi)(shi)間更(geng)長（可達數小時(shi)(shi)）。并且電(dian)(dian)路更(geng)加(jia)簡單(dan)，采(cai)用(yong)TO-94或SOT-23-4封裝，就像一(yi)個(ge)三極(ji)管(guan)一(yi)樣。而價錢也跟CD4060差不多，使用(yong)效果可就好的(de)太多了。

至此(ci)大(da)家想必也(ye)大(da)致(zhi)了(le)解了(le)圖三的(de)(de)工作流(liu)(liu)程(cheng)(cheng)了(le)：接(jie)上電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)和充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)器，如果電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)壓低(di)(di)于2.8V，則(ze)U1輸出(chu)為(wei)低(di)(di)（U2輸出(chu)也(ye)是低(di)(di)），這樣R3和R4的(de)(de)回(hui)路(lu)都不通，只(zhi)有(you)R2回(hui)路(lu)導(dao)通，給(gei)Q1提(ti)供(gong)(gong)微(wei)弱(ruo)的(de)(de)導(dao)通，使(shi)之輸出(chu)約數毫(hao)(hao)安的(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)給(gei)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)進行預充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，當電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)壓上升到(dao)超過(guo)2.94V（1.05X2.8）時(shi)(shi)或者剛接(jie)上電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)壓就(jiu)超過(guo)2.94V時(shi)(shi)，U1輸出(chu)高(gao)電(dian)(dian)(dian)(dian)(dian)平而U2繼續輸出(chu)低(di)(di)電(dian)(dian)(dian)(dian)(dian)平（電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)壓還沒達到(dao)4.2V J），這時(shi)(shi)R2通路(lu)截止(zhi)而R3通路(lu)導(dao)通（因(yin)為(wei)Q4導(dao)通且其源極電(dian)(dian)(dian)(dian)(dian)平為(wei)低(di)(di)-因(yin)U1輸出(chu)拉低(di)(di)），從而由較小(xiao)(xiao)阻(zu)值的(de)(de)R3令Q1完全(quan)導(dao)通，提(ti)供(gong)(gong)一個(ge)數百(bai)毫(hao)(hao)安的(de)(de)大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)恒(heng)流(liu)(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，而當這個(ge)恒(heng)流(liu)(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)過(guo)程(cheng)(cheng)慢(man)慢(man)令到(dao)被充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)的(de)(de)Li+電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)端電(dian)(dian)(dian)(dian)(dian)壓上升到(dao)4.2V時(shi)(shi)，U2也(ye)輸出(chu)高(gao)電(dian)(dian)(dian)(dian)(dian)平從而關(guan)閉(bi)Q4,但是它同時(shi)(shi)也(ye)給(gei)U3提(ti)供(gong)(gong)了(le)電(dian)(dian)(dian)(dian)(dian)源導(dao)致(zhi)U3開(kai)始工作，這樣U3觸發Q3使(shi)R4導(dao)通提(ti)供(gong)(gong)一個(ge)很小(xiao)(xiao)的(de)(de)補(bu)充(chong)(chong)(chong)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，直(zhi)至U3達到(dao)定(ding)時(shi)(shi)時(shi)(shi)間從而關(guan)閉(bi)Q3，這時(shi)(shi)整個(ge)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)過(guo)程(cheng)(cheng)才完全(quan)結束(shu)。

相比(bi)而言，第二(er)個方案增加(jia)了前期智能判斷電(dian)(dian)池狀態和自動預充(chong)(chong)電(dian)(dian)過程，以及延長了末(mo)尾的補充(chong)(chong)充(chong)(chong)電(dian)(dian)過程的時間，各個階段的充(chong)(chong)電(dian)(dian)電(dian)(dian)流可(ke)調(diao)并且補充(chong)(chong)充(chong)(chong)電(dian)(dian)時間可(ke)調(diao)（數分鐘至數小(xiao)時），因(yin)此該(gai)方案對鋰電(dian)(dian)池充(chong)(chong)電(dian)(dian)具有更好的精(jing)確性和安全(quan)性，加(jia)上價錢便宜(yi)，功能也比(bi)較(jiao)完善，相信很(hen)快(kuai)會取(qu)代市面中低(di)檔的充(chong)(chong)電(dian)(dian)器特別是(shi)那(nei)些廉價的手機電(dian)(dian)池充(chong)(chong)電(dian)(dian)器。