在市場(chang)上，能量(liang)收(shou)集(ji) IC 剛剛進(jin)入(ru)最初(chu)采用階(jie)段。能量(liang)收(shou)集(ji) IC 可將適合的(de)(de)換能器(qi)輸(shu)出轉換成電流，用于電池充電器(qi)設(she)備(bei)。盡管能量(liang)收(shou)集(ji)自 2000 年(nian)初(chu)就已經出現(xian)了，但是最近的(de)(de)技(ji)術(shu)發(fa)展才將能量(liang)收(shou)集(ji)推進(jin)到(dao)可商用的(de)(de)程度。在能量(liang)收(shou)集(ji)應用領域(yu)有很多(duo)機會，包括(kuo)：

　　? 在更換電(dian)(dian)池不(bu)方便、不(bu)現實(shi)或危險的情況下，取代電(dian)(dian)池供(gong)電(dian)(dian)系(xi)(xi)統或給電(dian)(dian)池供(gong)電(dian)(dian)系(xi)(xi)統再充電(dian)(dian)

　　? 無需導線來供電(dian)或傳送數據(ju)

　　? 用(yong)智能無線(xian)傳感器(qi)網絡監視和優化復雜的工(gong)業過(guo)程(cheng)、安裝在偏遠現場(chang)的設備(bei)、以及大樓的加熱(re)和冷卻(que)系統

　　? 從工業過(guo)程、太陽能(neng)電池板、內燃機等收集否則會浪費掉(diao)的熱量

　　? 各種不同的消費電子產品的附屬充電器

　　在(zai)這些應(ying)用中(zhong)，有很多含有固有的斷續(xu)或(huo)低功率電(dian)源。而(er)且，有很多應(ying)用將需要(yao)給電(dian)池充電(dian)，以提供一(yi)個(ge)備份電(dian)源。

　　并(bing)聯(lian)電(dian)(dian)(dian)壓基(ji)準簡單易用，已經(jing)出現(xian)(xian)很多(duo)年(nian)了，有(you)大量(liang)產品。不過，這類基(ji)準不能有(you)效(xiao)地給電(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)。要配置一個并(bing)聯(lian)電(dian)(dian)(dian)壓基(ji)準以給電(dian)(dian)(dian)池(chi)有(you)效(xiao)充(chong)(chong)電(dian)(dian)(dian)是(shi)(shi)極端(duan)復雜(za)的。此(ci)外(wai)，用一個小電(dian)(dian)(dian)流(liu)電(dian)(dian)(dian)源(yuan)(yuan)或一個斷續性(xing)能量(liang)收集電(dian)(dian)(dian)源(yuan)(yuan)準確和安全地給鋰離子 / 聚合(he)物、幣形電(dian)(dian)(dian)池(chi)或薄膜電(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)，一直(zhi)是(shi)(shi)難(nan)以實現(xian)(xian)的。

　　從(cong)電(dian)池(chi)(chi)(chi)方面(mian)來看，盡管技(ji)(ji)術(shu)已經改進(jin)了，但是(shi)便攜(xie)式(shi)電(dian)子(zi)設備的(de)電(dian)池(chi)(chi)(chi)或電(dian)池(chi)(chi)(chi)組(zu)仍(reng)然(ran)需(xu)要(yao)保(bao)護(hu)和(he)查(cha)驗(yan)，以保(bao)持電(dian)池(chi)(chi)(chi)在最佳(jia)狀態運行(xing)。鋰(li)離子(zi) / 聚合物電(dian)池(chi)(chi)(chi)技(ji)(ji)術(shu)已經成(cheng)(cheng)熟，是(shi)很多電(dian)子(zi)設備流(liu)行(xing)的(de)電(dian)源選擇，因(yin)為這(zhe)類電(dian)池(chi)(chi)(chi)能(neng)(neng)量密度(du)高(gao)、自(zi)放電(dian)很少、需(xu)要(yao)很少的(de)維護(hu)、電(dian)壓(ya)范(fan)圍很寬并具(ju)有(you)其(qi)他一(yi)些特(te)(te)色。幣形(xing)(xing)電(dian)池(chi)(chi)(chi)能(neng)(neng)量密度(du)高(gao)、放電(dian)特(te)(te)性穩定、重量輕且外形(xing)(xing)尺寸小(xiao)。薄膜電(dian)池(chi)(chi)(chi)是(shi)一(yi)種新出現的(de)技(ji)(ji)術(shu)，優勢是(shi)允許非(fei)常多的(de)充(chong)電(dian)周期(qi)次(ci)數(shu)，并具(ju)有(you)物理靈活性，即(ji)視最終應用(yong)的(de)不(bu)同而不(bu)同，薄膜電(dian)池(chi)(chi)(chi)可(ke)以做成(cheng)(cheng)幾乎(hu)任何形(xing)(xing)狀。不(bu)過，如果不(bu)能(neng)(neng)正確充(chong)電(dian)和(he)查(cha)驗(yan)，那么所有(you)這(zhe)些類型的(de)電(dian)池(chi)(chi)(chi)都可(ke)能(neng)(neng)受到一(yi)些有(you)害影響。

　　低功(gong)耗充電器的設計(ji)挑戰(zhan)

　　可調(diao)并聯基(ji)(ji)準可被(bei)設(she)定以(yi)提供恰當(dang)的電(dian)(dian)池浮置(zhi)電(dian)(dian)壓，但是(shi)這(zhe)(zhe)類基(ji)(ji)準缺(que)乏(fa)電(dian)(dian)池充(chong)電(dian)(dian)器的 NTC 功能。更重要的是(shi)，所需的工作電(dian)(dian)流太高了，以(yi)至于用低功率電(dian)(dian)源或(huo)(huo)斷續性電(dian)(dian)源給電(dian)(dian)池充(chong)電(dian)(dian)是(shi)不現(xian)實(shi)的。或(huo)(huo)者，可以(yi)用一(yi)(yi)(yi)個齊納二極管、一(yi)(yi)(yi)些電(dian)(dian)阻器、一(yi)(yi)(yi)個 NPN 晶體管和(he)一(yi)(yi)(yi)些比(bi)(bi)較(jiao)器構成(cheng)一(yi)(yi)(yi)個分(fen)立式(shi)并聯基(ji)(ji)準，以(yi)提供 NTC 功能。不過，這(zhe)(zhe)樣的并聯基(ji)(ji)準仍然受(shou)到前(qian)述限制。此(ci)外，分(fen)立式(shi)并聯基(ji)(ji)準實(shi)現(xian)起來比(bi)(bi)較(jiao)復雜，相比(bi)(bi)之下，會占用更多寶貴的 PCB 面積(ji)。

　　典(dian)型的電(dian)池充電(dian)器(qi) IC 需(xu)要恒定 DC 輸入(ru)電(dian)壓，而且(qie)不(bu)能(neng)處理能(neng)量突(tu)(tu)發。不(bu)過，諸如(ru)室(shi)內光伏陣列或壓電(dian)換(huan)能(neng)器(qi)等斷(duan)續(xu)性能(neng)量收集電(dian)源提供的是功率突(tu)(tu)發。要用這(zhe)類能(neng)源給電(dian)池充電(dian)，一個靜態工(gong)作(zuo)電(dian)流低于 1uA 的獨特 IC 是必需(xu)的。

　　鋰離子 / 聚合物化學組(zu)成的(de)電(dian)(dian)池(chi)(chi)(chi)提供便(bian)攜式電(dian)(dian)子設備必(bi)需的(de)高性能(neng)，但是這(zhe)類電(dian)(dian)池(chi)(chi)(chi)必(bi)須小(xiao)心(xin)使(shi)用。例(li)如(ru)(ru)，如(ru)(ru)果用比建議浮置電(dian)(dian)壓(ya)高 100mV 的(de)電(dian)(dian)壓(ya)充電(dian)(dian)，鋰離子 / 聚合物電(dian)(dian)池(chi)(chi)(chi)可能(neng)變得不穩定。此外，高壓(ya)和高溫(wen)同(tong)時(shi)存(cun)在會(hui)對電(dian)(dian)池(chi)(chi)(chi)壽(shou)命產生有(you)害影響，而(er)且在極端情況下，可能(neng)導致電(dian)(dian)池(chi)(chi)(chi)自毀。就幣形電(dian)(dian)池(chi)(chi)(chi)和薄(bo)膜電(dian)(dian)池(chi)(chi)(chi)而(er)言，除了高溫(wen)和高壓(ya)同(tong)時(shi)存(cun)在可能(neng)產生有(you)害影響，還(huan)有(you)容量(liang)問題，因為它們的(de)外形尺寸很(hen)小(xiao)。

　　并聯架構的基本要素和好處

　　并(bing)聯基(ji)準(zhun)是電(dian)(dian)流饋(kui)送(song)型、兩(liang)端(duan)子電(dian)(dian)路，在達到目標電(dian)(dian)壓(ya)之(zhi)前不吸取電(dian)(dian)流。并(bing)聯基(ji)準(zhun)用起來像(xiang)一個(ge)(ge)齊(qi)納二(er)極管，而且在電(dian)(dian)路原理圖上常常顯示(shi)為(wei)一個(ge)(ge)齊(qi)納二(er)極管。不過，大多數(shu)并(bing)聯基(ji)準(zhun)實際上都是基(ji)于帶隙(xi)基(ji)準(zhun)電(dian)(dian)壓(ya)的。

　　一個并聯(lian)基準僅需要單個外部電(dian)阻(zu)器來調節輸出電(dian)壓(ya)，從而極其(qi)容易使用。沒有最(zui)高輸入電(dian)壓(ya)限制，最(zui)低輸入電(dian)壓(ya)由基準電(dian)壓(ya)值(zhi)設定，因為(wei)需要一些空(kong)間(jian)以正(zheng)常(chang)運行。

　　此外(wai)，并(bing)聯(lian)基準在(zai)寬(kuan)電流范圍內(nei)有良好的穩(wen)定(ding)性。很(hen)多并(bing)聯(lian)基準在(zai)有大型或小型容性負載(zai)時(shi)都是穩(wen)定(ding)的。

　　滿足前述電池充電器 IC 設計限制(zhi)的(de)任何解決方案都必(bi)須兼有如下(xia)特(te)性(xing)：并聯穩壓器的(de)特(te)性(xing);能用低功(gong)率連(lian)續或(huo)斷續性(xing)電(dian)(dian)(dian)源充電(dian)(dian)(dian)的(de)電(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian) IC 的(de)特(te)性(xing)。這(zhe)樣的(de)器件(jian)還需(xu)要保(bao)護鋰離子/聚合物電(dian)(dian)(dian)池(chi)(chi)、幣形電(dian)(dian)(dian)池(chi)(chi)、薄膜電(dian)(dian)(dian)池(chi)(chi)或(huo)電(dian)(dian)(dian)池(chi)(chi)組(zu)的(de)安全，并使電(dian)(dian)(dian)池(chi)(chi)或(huo)電(dian)(dian)(dian)池(chi)(chi)組(zu)達到最高(gao)性(xing)能。

　　凌力(li)爾(er)特開發了業界第一款(kuan)(kuan)并(bing)(bing)聯(lian)(lian)架(jia)構電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)器(qi) LTC4070 和(he) LTC4071，以(yi)滿足這(zhe)類應用(yong)(yong)(yong)(yong)的需求。LTC4070 是(shi)一款(kuan)(kuan)易用(yong)(yong)(yong)(yong)、纖巧的并(bing)(bing)聯(lian)(lian)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)器(qi)系統 IC，適(shi)用(yong)(yong)(yong)(yong)于鋰離(li)子 / 聚(ju)合物電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)、幣(bi)(bi)形電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)或薄膜電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)。該 IC 的工作(zuo)電(dian)(dian)(dian)流為 450nA，可(ke)保護(hu)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)，并(bing)(bing)可(ke)用(yong)(yong)(yong)(yong)以(yi)前不(bu)能使(shi)用(yong)(yong)(yong)(yong)的非常(chang)小電(dian)(dian)(dian)流的斷(duan)續(xu)性或連續(xu)性充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)源(yuan)給(gei)這(zhe)些電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)。增加一個(ge)外部(bu) PMOS 并(bing)(bing)聯(lian)(lian)器(qi)件(jian)，LTC4070 的充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流就可(ke)以(yi)從 50mA 提高到 500mA。當(dang)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)溫(wen)度升高時，內部(bu)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)熱量查驗器(qi)降(jiang)低浮置電(dian)(dian)(dian)壓(ya)，以(yi)保護(hu)鋰離(li)子 / 聚(ju)合物電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)的安全(quan)。通過串聯(lian)(lian)配置幾(ji)個(ge) LTC4070，可(ke)以(yi)給(gei)由多節(jie)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)組(zu)(zu)成(cheng)的電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)組(zu)(zu)充(chong)(chong)電(dian)(dian)(dian)，并(bing)(bing)實(shi)現各節(jie)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)的容量平衡。LTC4070 采用(yong)(yong)(yong)(yong)扁(bian)平 (0.75mm) 8 引線 2mm x 3mm DFN 封裝(zhuang)，僅用(yong)(yong)(yong)(yong)單個(ge)外部(bu)電(dian)(dian)(dian)阻(zu)器(qi) (要求與輸入電(dian)(dian)(dian)壓(ya)串聯(lian)(lian)) 就能組(zu)(zu)成(cheng)一個(ge)完整(zheng)和(he)超(chao)緊(jin)湊的充(chong)(chong)電(dian)(dian)(dian)器(qi)解決方案。該器(qi)件(jian)的功(gong)能集使(shi)其非常(chang)適(shi)用(yong)(yong)(yong)(yong)于連續(xu)性和(he)斷(duan)續(xu)性低功(gong)率充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)源(yuan)應用(yong)(yong)(yong)(yong)，包括(kuo)鋰離(li)子 / 聚(ju)合物電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)備份、薄膜電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)、幣(bi)(bi)形電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)、存儲器(qi)備份、太陽能供電(dian)(dian)(dian)系統、嵌入式汽車(che)和(he)能量收(shou)集。

　　LTC4070提供引(yin)腳可選的(de)(de)(de) 4.0V、4.1V 和(he) 4.2V 設(she)置(zhi)，其(qi)準確度(du)為 1% 的(de)(de)(de)電(dian)(dian)(dian)池(chi)(chi)浮置(zhi)電(dian)(dian)(dian)壓允許用戶在電(dian)(dian)(dian)池(chi)(chi)能量(liang)(liang)(liang)密度(du)和(he)壽命之間(jian)進行取舍。獨立(li)的(de)(de)(de)低電(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)量(liang)(liang)(liang)和(he)高電(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)量(liang)(liang)(liang)監察狀(zhuang)態(tai)輸出(chu)指示放(fang)電(dian)(dian)(dian)或完(wan)全充電(dian)(dian)(dian)的(de)(de)(de)電(dian)(dian)(dian)池(chi)(chi)。再加上一個與負載串聯(lian)的(de)(de)(de)外部 P-FET，該(gai)低電(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)量(liang)(liang)(liang)狀(zhuang)態(tai)輸出(chu)可實(shi)現鎖斷功能，該(gai)功能自動斷接系統負載和(he)電(dian)(dian)(dian)池(chi)(chi)，以防止電(dian)(dian)(dian)池(chi)(chi)深(shen)度(du)放(fang)電(dian)(dian)(dian)。

　　除了緊湊的 2mm x 3mm 8 引線(xian) DFN 封(feng)裝，LTC4070 還(huan)采(cai)用 8 引線(xian) MSOP。這些器件(jian)規定(ding)在 -40?C 至(zhi) 125?C 的溫度范(fan)圍內工作。

　　通過防止(zhi)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓超過設定水(shui)平，LTC4070 提供(gong)了一個(ge)簡單、可靠、高(gao)性能的(de)電(dian)(dian)(dian)(dian)(dian)池(chi)保護(hu)和充電(dian)(dian)(dian)(dian)(dian)解決方(fang)案(an)。其并聯架(jia)構在輸入(ru)電(dian)(dian)(dian)(dian)(dian)源(yuan)和電(dian)(dian)(dian)(dian)(dian)池(chi)之間(jian)僅(jin)需要一個(ge)電(dian)(dian)(dian)(dian)(dian)阻器，就可應對多種電(dian)(dian)(dian)(dian)(dian)池(chi)應用。當輸入(ru)電(dian)(dian)(dian)(dian)(dian)源(yuan)去掉(diao)，且(qie)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓低(di)于高(gao)的(de)電(dian)(dian)(dian)(dian)(dian)池(chi)輸出門(men)限時，LTC4070 僅(jin)從電(dian)(dian)(dian)(dian)(dian)池(chi)吸取 450nA 電(dian)(dian)(dian)(dian)(dian)流(liu)。

　　當電(dian)池電(dian)壓(ya)低(di)于設(she)定的浮置電(dian)壓(ya)時，充電(dian)速率由輸(shu)入電(dian)壓(ya)、電(dian)池電(dian)壓(ya)和輸(shu)入電(dian)阻(zu)器(qi)決(jue)定：

　　ICHG = (VIN ? VBAT) / RIN

　　當電(dian)(dian)池電(dian)(dian)壓(ya)接近浮置(zhi)電(dian)(dian)壓(ya)時(shi)，LTC4070 從電(dian)(dian)池分(fen)走一(yi)部(bu)(bu)分(fen)電(dian)(dian)流(liu)，從而降(jiang)低了充(chong)電(dian)(dian)電(dian)(dian)流(liu)。在整個(ge)溫度范(fan)圍(wei)內(nei)變化浮置(zhi)電(dian)(dian)壓(ya)的準確(que)度為(wei) ±1% 時(shi)，LTC4070 可以(yi)分(fen)走高達 50mA 的電(dian)(dian)流(liu)。分(fen)流(liu)限(xian)制了最大充(chong)電(dian)(dian)電(dian)(dian)流(liu)，不過通過增加(jia)一(yi)個(ge)外部(bu)(bu) P 溝(gou)道(dao) MOSFET，50mA 的內(nei)部(bu)(bu)分(fen)流(liu)能力(li)還可以(yi)提(ti)高，參見圖(tu) 1。

　　在(zai)內部，LTC4070 采用了一個由放大器 EA (參見圖 2) 驅動(dong)的(de)(de) P 溝道 MOSFET。VCC 和(he) GND 之間(jian)的(de)(de)電(dian)(dian)壓(ya)達到(dao) VF (即并(bing)聯電(dian)(dian)壓(ya)) 之前(qian)，流(liu)經該器件的(de)(de)電(dian)(dian)流(liu)為零。VF 可以(yi)由 ADJ 和(he) NTC 改變(bian)，但始(shi)終(zhong)在(zai) 3.8V 到(dao) 4.2V 之間(jian)。如(ru)果 VCC 電(dian)(dian)壓(ya)低于這個值，那么 PFET 中的(de)(de)電(dian)(dian)流(liu)為零。如(ru)果 VCC電(dian)(dian)壓(ya)試圖上(shang)(shang)升(sheng)到(dao)超(chao)過 VF，那么電(dian)(dian)流(liu)將流(liu)過該器件，以(yi)防止電(dian)(dian)壓(ya)上(shang)(shang)升(sheng)，這就(jiu)是分(fen)流(liu)。

　　工作電(dian)流是給該芯片中(zhong)其(qi)余所(suo)有電(dian)路(lu)供電(dian)所(suo)需(xu)的(de)電(dian)流。如果(guo)不存在外(wai)部(bu)電(dian)源，那么這就是從電(dian)池(chi)吸取(qu)的(de)電(dian)流。

　　當電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)低時(shi)(shi)，更多的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)加在輸入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)器(qi)兩端，因此進入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流 (即(ji)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流) 略大于電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)完全充電(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流。當電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充滿電(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)，將(jiang)沒(mei)有電(dian)(dian)(dian)(dian)(dian)(dian)流進入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)，所(suo)有的(de)輸入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)(dian)流都將(jiang)進入(ru)(ru)分(fen)流器(qi)。

　　工作電(dian)(dian)(dian)(dian)(dian)流很重要，因(yin)為它給“實際”輸入(ru)電(dian)(dian)(dian)(dian)(dian)源的電(dian)(dian)(dian)(dian)(dian)流能(neng)力(li)(li)設(she)定了(le)一個(ge)低限制。顯然，一個(ge)僅(jin)有 100nA驅動(dong)(dong)能(neng)力(li)(li)的輸入(ru)電(dian)(dian)(dian)(dian)(dian)源不可(ke)能(neng)給采用 LTC4070 的電(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)。不過，如(ru)果有 1uA 的驅動(dong)(dong)能(neng)力(li)(li)，就能(neng)剩下(xia)少(shao)量電(dian)(dian)(dian)(dian)(dian)流去充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)。如(ru)果能(neng)得到 10uA 的驅動(dong)(dong)能(neng)力(li)(li)，那么該電(dian)(dian)(dian)(dian)(dian)流 90% 以(yi)上(shang)都可(ke)用于充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)。

　　NTC 電(dian)(dian)池查(cha)驗電(dian)(dian)路保護電(dian)(dian)池

　　LTC4070 用一個通過(guo)熱(re)量耦合到電(dian)池的(de)負溫度(du)系數熱(re)敏電(dian)阻測量電(dian)池溫度(du)。NTC 熱(re)敏電(dian)阻的(de)溫度(du)特性在(zai)電(dian)阻-溫度(du)轉換表中規定。在(zai)溫度(du)高于 40°C 以后，每上升 10°C，內部 NTC 電(dian)路就降低一次浮置(zhi)電(dian)壓，以防止電(dian)池過(guo)熱(re) (參見(jian)圖(tu) 3 以了解詳細信息)。

　　LTC4070 采用一(yi)個(ge)電(dian)(dian)阻值之(zhi)比來測量(liang)(liang)電(dian)(dian)池溫(wen)度。LTC4070 在 NTCBIAS 與 GND 引腳(jiao)之(zhi)間布設了(le)一(yi)個(ge)具 4 個(ge)抽頭的內部(bu)固定電(dian)(dian)阻分(fen)壓器。定期地將這些(xie)抽頭上的電(dian)(dian)壓與 NTC 引腳(jiao)上的電(dian)(dian)壓進行(xing)比較，以測量(liang)(liang)電(dian)(dian)池溫(wen)度。為(wei)了(le)節省功率(lv)，通過以大約每 1.5s 一(yi)次的頻度把 NTCBIAS 引腳(jiao)偏(pian)置至 VCC 來定期測量(liang)(liang)電(dian)(dian)池溫(wen)度。

    LTC4070 具(ju)有一個(ge)(ge)與 ADJ 引(yin)腳(jiao)相(xiang)連(lian)(lian)的(de)(de)內置三(san)態解碼器(qi)，用以提(ti)供 3 種可編程浮置電(dian)(dian)壓(ya)(ya)：4.0V、4.1V、或(huo) 4.2V。當 ADJ 引(yin)腳(jiao)連(lian)(lian)接(jie)至 GND、浮置或(huo)連(lian)(lian)接(jie)至 VCC 時，浮置電(dian)(dian)壓(ya)(ya)將被分別(bie)設置為(wei) 4.0V、4.1V 或(huo) 4.2V。大約每 1.5s 對(dui) ADJ 引(yin)腳(jiao)的(de)(de)狀態進(jin)行一次采樣(yang)。當 ADJ 引(yin)腳(jiao)被采樣(yang)時，LTC4070 在其上施加(jia)一個(ge)(ge)相(xiang)對(dui)較(jiao)低(di)的(de)(de)阻抗(kang)電(dian)(dian)壓(ya)(ya)。這種做法可以防止低(di)水平(ping)的(de)(de)電(dian)(dian)路板漏電(dian)(dian)流(liu)破壞設定的(de)(de)浮置電(dian)(dian)壓(ya)(ya)。免除電(dian)(dian)阻器(qi)不僅縮減了(le)(le)解決方案的(de)(de)外(wai)形尺寸，而(er)且還由于無需使(shi)用大阻值(zhi)的(de)(de)電(dian)(dian)阻器(qi)而(er)降低(di)了(le)(le)靜態電(dian)(dian)流(liu)。

　　另外，該器件還具有(you)狀態輸出(chu)及發(fa)送指(zhi)示(shi)信號(hao)的(de)能(neng)力。高電(dian)(dian)池(chi)電(dian)(dian)量監視器輸出(chu) (HBO) 是一個高態有(you)效 CMOS 輸出(chu)，當電(dian)(dian)池(chi)充(chong)滿電(dian)(dian)且(qie)電(dian)(dian)流(liu)通過分路離開 BAT 時(shi)，該輸出(chu)將發(fa)出(chu)指(zhi)示(shi)信號(hao)。低電(dian)(dian)池(chi)電(dian)(dian)量監視器輸出(chu) (LBO) 也是一個高態有(you)效 CMOS 輸出(chu)，當電(dian)(dian)池(chi)放電(dian)(dian)至 3.2V 以下(xia)時(shi)，此(ci)輸出(chu)將發(fa)出(chu)對應(ying)的(de)指(zhi)示(shi)信號(hao)。最(zui)后，外部驅動(dong)器輸出(chu)引腳 DRV 可(ke)連接至外部 P-FET 的(de)柵極以增加分路電(dian)(dian)流(liu)，從而(er)滿足那些需(xu)要(yao) 50mA 以上充(chong)電(dian)(dian)電(dian)(dian)流(liu) (最(zui)大 500mA) 的(de)應(ying)用。

　　LTC4071 集(ji)成電池組保護(hu)功能(neng)

　　LTC4071 也(ye)是一(yi)(yi)個(ge)(ge)(ge)并聯(lian)(lian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)系統(tong)，而且(qie)還是首款具(ju)有集成型電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組保護功(gong)能(neng) (包括低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接) 的器(qi)件。相比于(yu) LTC4070，LTC4071 的不(bu)(bu)同之(zhi)處包括：其(qi)擁有集成型電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組保護功(gong)能(neng) (低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接) 、但充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)能(neng)力(li)較低(di)(di) (50mA)、靜(jing)態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)較高(gao) (550nA) 、且(qie)不(bu)(bu)具(ju)備 LBO。對于(yu)避免低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)由于(yu)自(zi)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)而受損(sun)而言，低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接是一(yi)(yi)種必需的關鍵性功(gong)能(neng)。雖(sui)然 LTC4070 能(neng)夠(gou)利用 LBO 和一(yi)(yi)個(ge)(ge)(ge)外部(bu) P-FET 來(lai)實現(xian)低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接功(gong)能(neng)，但該 IC 仍(reng)將繼續(xu)從電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)消耗全(quan)部(bu) IQ (約 0.5μA)。即使是如此之(zhi)小的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)漏電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)也(ye)會在一(yi)(yi)夜(ye)之(zhi)間導致(zhi)低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的損(sun)壞。相反，LTC4071 集成了(le)(le)一(yi)(yi)個(ge)(ge)(ge)徹底的低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接功(gong)能(neng)，當斷(duan)接時(shi)，從電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)吸取的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)接近零 (在室溫(wen)時(shi) <1nA，在 125°C 時(shi) < 25nA)。為了(le)(le)在 LTC4071 中提供這一(yi)(yi)功(gong)能(neng)，相應于(yu) LTC4070 的 LBO 和 DRV 引腳(jiao)被去掉了(le)(le)。參見圖 4 以(yi)了(le)(le)解詳細信(xin)息。這使 LTC4071 的最(zui)大(da)分流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)固定為 50mA (LTC4070 是 50mA，但采用一(yi)(yi)個(ge)(ge)(ge)外部(bu) FET，就能(neng)達到 500mA)，而且(qie)將該 IC 的靜(jing)態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)提高(gao)到了(le)(le) 550nA (LTC4070 的靜(jing)態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)為 450nA)。下表 1 總(zong)結(jie)了(le)(le)這兩個(ge)(ge)(ge)相互關聯(lian)(lian)的 IC 之(zhi)間的差(cha)別。

　　結論

　　并聯基準有很多應(ying)用(yong)，而且視其功(gong)(gong)能的(de)不(bu)(bu)同(tong)(tong)而不(bu)(bu)同(tong)(tong)，并聯基準甚至可以(yi)用(yong)來給(gei)電池(chi)(chi)充電。不(bu)(bu)過，這種類型的(de)應(ying)用(yong)有很多缺點，包括大(da)靜態電流和(he)缺乏電池(chi)(chi)保護(hu)功(gong)(gong)能。現在，有了合(he)適的(de) DC-DC 轉(zhuan)換器(qi)或(huo)電池(chi)(chi)充電器(qi)，因(yin)此(ci)可以(yi)對(dui)低功(gong)(gong)率能量收集(ji)應(ying)用(yong)進行(xing)查驗了。凌力爾特公司開發了 LTC4070 和(he) LTC4071 并聯充電器(qi)系(xi)統，這兩(liang)款(kuan)器(qi)件適用(yong)于鋰離子(zi) / 聚合(he)物電池(chi)(chi)、幣形電池(chi)(chi)、薄膜電池(chi)(chi)和(he)電池(chi)(chi)組，可為具有低功(gong)(gong)率電源(yuan)的(de)領先應(ying)用(yong)提供一種簡單、有效的(de)電池(chi)(chi)充電和(he)電池(chi)(chi)組保護(hu)解決方案(an)。