鋰電池充電IC-LP3947是一款內置微處理器，是功能完善的單節鋰電池充電集成電路,它具有可以采用USB接口或AC電源適配器供電,內置調整管構成的線性充電單元,它可以用于安穩電源(LDO形式),輸出電流可達1A,停止電壓為4.1V或4.2V的電池,恒流恒壓充電,并可對過放電電池進行預充電,內置電池溫度檢測,電池溫度過高或過低時,充電器自動關斷,有5.6小時安全定時器,有過流和過熱保護,充電狀況指示,充電電流檢測,并輸出與充電電流成份額的模擬電壓,器材結溫TJ在0℃≤TJ≤85℃。規模內,充電精度在1%內,輸入電壓規模:4.3V—6.0V，在AC適配器供電時，充電電流設定規模為100mA—750mA，在USB端口供電時，充電電流設定規模為100-500mA。工作溫度：-40℃—+85℃。

圖(tu)(tu)為(wei)其引腳示(shi)意圖(tu)(tu)，該IC可廣泛應用(yong)于移動(dong)電(dian)話，數碼相機，USB供電(dian)的IT設備和掌上電(dian)器.LP3947各管(guan)腳功能闡(chan)明(ming)如下：

• Pin1(EN):充電輸入(ru)使能端，輸入(ru)高電平答應充電，低電平制止充電。
• Pin2(SCL):I2C串行接(jie)口(kou)時(shi)鐘(zhong)輸入端。
• Pin3(SDA):I2C串行(xing)接口數據輸入(ru)/輸出(chu)端。
• Pin4(BATT):電(dian)池充(chong)電(dian)輸入端，此端接10uF陶瓷電(dian)容至地。
• Pin5(VT):2.78V安(an)(an)穩電(dian)壓輸出端(duan)，用于丈量電(dian)池溫度的安(an)(an)穩電(dian)源。
• Pin6(VBSENSE):電池電壓檢測端，與電池的正極相連。
• Pin7(MODE):挑選AC適配器(qi)供(gong)電(dian)(置高電(dian)平)，挑選USB供(gong)電(dian)(置低電(dian)平)。
• Pin8(Diff-Amp):檢(jian)測(ce)充電(dian)電(dian)流(liu)的差動放大器輸(shu)出(chu)，輸(shu)出(chu)電(dian)壓(ya)正(zheng)比于充電(dian)電(dian)流(liu)。
• Pin9(Ts):多功能端(duan)(duan)，電(dian)(dian)池溫度檢(jian)測輸入(ru)(ru)端(duan)(duan)，用于(yu)LDO形(xing)(xing)式/充電(dian)(dian)器形(xing)(xing)式輸入(ru)(ru)端(duan)(duan)，若不裝入(ru)(ru)充電(dian)(dian)電(dian)(dian)池，則為LDO形(xing)(xing)式，用作低壓差4.1V或4.2V輸出(chu)穩壓器。
• Pin10(EOC):內部為開漏輸出，當(dang)USB端口或AC適(shi)配器被(bei)連(lian)接(jie)，電(dian)池(chi)已充溢(yi)(yi)時，此端輸出低(di)電(dian)平(ping)，可外(wai)接(jie)一顆LED，亮表明電(dian)池(chi)已充溢(yi)(yi)。
• Pin11(GND):地端。
• Pin12(CHG):內部為(wei)開漏輸(shu)出，當USB端(duan)口或AC適配器(qi)被連接(jie)，電池開端(duan)充電，此端(duan)輸(shu)出低電平，可外接(jie)一顆LED，亮表明電池已開端(duan)充電。
• Pin13(ISEL):充(chong)電(dian)(dian)器在(zai)USB端口(kou)供電(dian)(dian)，此(ci)端接(jie)高電(dian)(dian)平(ping)，充(chong)電(dian)(dian)電(dian)(dian)流(liu)(liu)為100mA此(ci)端接(jie)低電(dian)(dian)平(ping)，充(chong)電(dian)(dian)電(dian)(dian)流(liu)(liu)為500mA(別的(de)I2C接(jie)口(kou)可設定充(chong)電(dian)(dian)電(dian)(dian)流(liu)(liu))。
• Pin14(CHG-IN):充(chong)電(dian)器供電(dian)輸入端，輸入一個穩壓(ya)有(you)電(dian)流約束的(de)電(dian)源，在此(ci)端必須接一個1uF陶瓷電(dian)容(rong)接地。

充(chong)電(dian)過程(cheng):LP3947組(zu)成的充(chong)電(dian)器電(dian)路(lu)如圖(tu)2，充(chong)電(dian)過程(cheng)及充(chong)電(dian)狀況指示(shi)見圖(tu)3，赤色LED為充(chong)電(dian)指示(shi)燈，綠色LED充(chong)溢指示(shi)燈，圖(tu)中的停(ting)止(zhi)充(chong)電(dian)電(dian)壓為4.1V.

充電(dian)(dian)器接上AC適(shi)配器或USB電(dian)(dian)源，充電(dian)(dian)器開(kai)端工作，假如輸入電(dian)(dian)壓(ya)(ya)在低閾(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(≥4.3V)高(gao)電(dian)(dian)壓(ya)(ya)閾(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(≤6.0V)充電(dian)(dian)器檢測到適(shi)合(he)的輸入電(dian)(dian)壓(ya)(ya)，預充電(dian)(dian)開(kai)端，赤色LED亮，綠色LED熄.

預充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)階(jie)段的充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)在40-70mA間(jian)，使(shi)過放電(dian)(dian)(dian)(dian)(dian)(dian)的電(dian)(dian)(dian)(dian)(dian)(dian)池以小電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)安全(quan)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓上升(sheng)，一直到電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓上升(sheng)到3.0V以上時，預充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)階(jie)段即告結(jie)束，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)定時器啟(qi)動，開(kai)端充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)。

快(kuai)充(chong)電(dian)階段的充(chong)電(dian)電(dian)流在ISEL端(duan)(duan)接高(gao)電(dian)平時(shi)(USB形式)，電(dian)流為100mA，在ISEL端(duan)(duan)接低電(dian)平時(shi)，電(dian)流為500mA，此刻若是使用AC適配(pei)器充(chong)電(dian)，快(kuai)充(chong)電(dian)流由用戶設定(100-750mA)快(kuai)充(chong)電(dian)電(dian)流精度在≤150mA時(shi)為±20mA，≥200mA為±10%，快(kuai)充(chong)電(dian)電(dian)壓(ya)到4.1V時(shi)，恒(heng)流充(chong)電(dian)階段結束，轉為4.1V恒(heng)壓(ya)充(chong)電(dian)。

恒(heng)壓(ya)充(chong)(chong)(chong)(chong)(chong)電(dian)階段(duan)充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)壓(ya)不(bu)變，但充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)流(liu)會(hui)逐漸下(xia)降，直到(dao)充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)流(liu)下(xia)降到(dao)必定(ding)程度(du)時(shi)(shi)(shi)，充(chong)(chong)(chong)(chong)(chong)電(dian)結束，此(ci)刻綠色LED亮(liang)，赤色LED熄，假如(ru)快充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)流(liu)為1C時(shi)(shi)(shi)，停(ting)止(zhi)充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)流(liu)可設定(ding)為0.1C，則恒(heng)壓(ya)充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)流(liu)下(xia)降到(dao)50mA，停(ting)止(zhi)充(chong)(chong)(chong)(chong)(chong)電(dian)，在(zai)100mA快充(chong)(chong)(chong)(chong)(chong)電(dian)電(dian)流(liu)時(shi)(shi)(shi)，定(ding)時(shi)(shi)(shi)器到(dao)5.6小時(shi)(shi)(shi)，停(ting)止(zhi)充(chong)(chong)(chong)(chong)(chong)電(dian)，此(ci)刻兩個LED都亮(liang)。

充(chong)電(dian)電(dian)流有IC內(nei)部的(de)(de)電(dian)流檢測電(dian)路檢測，有Diff-Amp輸(shu)(shu)出(chu)與(yu)充(chong)電(dian)電(dian)流成(cheng)份額(e)的(de)(de)電(dian)壓(ya)(輸(shu)(shu)入微處(chu)理器(qi)的(de)(de)ADC電(dian)壓(ya))，經微處(chu)理器(qi)操控后輸(shu)(shu)出(chu)停止充(chong)電(dian)信號，充(chong)電(dian)電(dian)流ICHG與(yu)Diff-Amp輸(shu)(shu)出(chu)電(dian)壓(ya)的(de)(de)VDIFF的(de)(de)關系為：

ICHG=(VDIFF-0.497)/1.655

注意(yi)：式(shi)中單位：電流為(wei)A，電壓(ya)為(wei)V。

停止(zhi)充(chong)電(dian)后若不取出(chu)電(dian)池，即進(jin)入(ru)維護狀況，當電(dian)池電(dian)壓下(xia)降0.2V時(shi)，則會進(jin)行補充(chong)充(chong)電(dian)，充(chong)電(dian)電(dian)壓到4.1V時(shi)又會停止(zhi)充(chong)電(dian)。