在(zai)市場(chang)上，能(neng)量(liang)收(shou)集 IC 剛剛進入(ru)最初采用(yong)(yong)階段。能(neng)量(liang)收(shou)集 IC 可將(jiang)適合的換能(neng)器(qi)輸出(chu)(chu)轉換成電(dian)流，用(yong)(yong)于(yu)電(dian)池充電(dian)器(qi)設備。盡管能(neng)量(liang)收(shou)集自 2000 年初就(jiu)已經(jing)出(chu)(chu)現(xian)了，但是最近的技(ji)術發展才(cai)將(jiang)能(neng)量(liang)收(shou)集推進到可商用(yong)(yong)的程度。在(zai)能(neng)量(liang)收(shou)集應(ying)用(yong)(yong)領域有很多機會，包括：

　　? 在更換電(dian)池(chi)(chi)不方便、不現實或危險的(de)情況下，取代電(dian)池(chi)(chi)供(gong)電(dian)系(xi)統(tong)或給(gei)電(dian)池(chi)(chi)供(gong)電(dian)系(xi)統(tong)再充電(dian)

　　? 無需導線來(lai)供電或傳送數據

　　? 用智能無線傳感(gan)器網(wang)絡監視和優化復雜的工業過程、安裝(zhuang)在(zai)偏遠現場的設備、以及大樓的加熱(re)和冷卻系統(tong)

　　? 從工業過程、太陽能電池板、內燃機等收集否則(ze)會浪費掉的熱量

　　? 各種不同的消費電子產品的附屬充電器

　　在這些應用(yong)中，有(you)很多含(han)有(you)固有(you)的斷續或(huo)低功率電源。而(er)且，有(you)很多應用(yong)將需要給(gei)電池(chi)充(chong)電，以(yi)提供一個(ge)備份電源。

　　并聯(lian)電(dian)(dian)壓基(ji)準簡單易用(yong)，已經出現很多年了，有大量(liang)產品。不過，這類基(ji)準不能有效地給(gei)電(dian)(dian)池(chi)充電(dian)(dian)。要配置一個(ge)并聯(lian)電(dian)(dian)壓基(ji)準以給(gei)電(dian)(dian)池(chi)有效充電(dian)(dian)是極端復雜(za)的(de)。此外，用(yong)一個(ge)小電(dian)(dian)流電(dian)(dian)源或(huo)一個(ge)斷續性(xing)能量(liang)收集電(dian)(dian)源準確(que)和安全地給(gei)鋰離子 / 聚(ju)合物、幣形電(dian)(dian)池(chi)或(huo)薄(bo)膜電(dian)(dian)池(chi)充電(dian)(dian)，一直是難以實現的(de)。

　　從(cong)電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)方面來看，盡管技術已(yi)經改進(jin)了，但是便攜式電(dian)(dian)子設備(bei)的(de)電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)或電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)組仍然需(xu)要(yao)保(bao)(bao)護和查驗，以保(bao)(bao)持電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)在最(zui)佳狀(zhuang)態(tai)運(yun)行。鋰離子 / 聚合物電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)技術已(yi)經成(cheng)熟(shu)，是很多電(dian)(dian)子設備(bei)流(liu)行的(de)電(dian)(dian)源選擇，因為這類電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)能量密度高、自放(fang)電(dian)(dian)很少(shao)、需(xu)要(yao)很少(shao)的(de)維護、電(dian)(dian)壓(ya)范圍很寬并具(ju)有其他一(yi)些特(te)色。幣形(xing)電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)能量密度高、放(fang)電(dian)(dian)特(te)性穩定、重量輕且(qie)外(wai)形(xing)尺寸小(xiao)。薄(bo)膜電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)是一(yi)種新出現的(de)技術，優勢是允許非(fei)常多的(de)充(chong)電(dian)(dian)周(zhou)期次數，并具(ju)有物理靈活性，即視最(zui)終應用(yong)的(de)不(bu)(bu)同而不(bu)(bu)同，薄(bo)膜電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)可(ke)以做成(cheng)幾乎(hu)任(ren)何形(xing)狀(zhuang)。不(bu)(bu)過(guo)，如果(guo)不(bu)(bu)能正確充(chong)電(dian)(dian)和查驗，那么所(suo)有這些類型的(de)電(dian)(dian)池(chi)(chi)(chi)(chi)(chi)都可(ke)能受到一(yi)些有害影(ying)響(xiang)。

　　低功(gong)耗充電器的設計挑戰

　　可調并(bing)(bing)聯(lian)基(ji)準(zhun)(zhun)可被設定以提供恰(qia)當的電(dian)(dian)池浮置(zhi)電(dian)(dian)壓，但是這(zhe)類基(ji)準(zhun)(zhun)缺乏(fa)電(dian)(dian)池充(chong)電(dian)(dian)器的 NTC 功能(neng)。更(geng)重要的是，所(suo)需的工作(zuo)電(dian)(dian)流太高了(le)，以至于用低功率電(dian)(dian)源(yuan)或斷續性電(dian)(dian)源(yuan)給電(dian)(dian)池充(chong)電(dian)(dian)是不現實的。或者，可以用一(yi)(yi)個(ge)齊(qi)納二極管、一(yi)(yi)些電(dian)(dian)阻器、一(yi)(yi)個(ge) NPN 晶體管和(he)一(yi)(yi)些比(bi)較(jiao)器構成一(yi)(yi)個(ge)分立式并(bing)(bing)聯(lian)基(ji)準(zhun)(zhun)，以提供 NTC 功能(neng)。不過(guo)，這(zhe)樣(yang)的并(bing)(bing)聯(lian)基(ji)準(zhun)(zhun)仍然受到(dao)前述限(xian)制。此(ci)外，分立式并(bing)(bing)聯(lian)基(ji)準(zhun)(zhun)實現起來比(bi)較(jiao)復(fu)雜(za)，相(xiang)比(bi)之(zhi)下，會(hui)占用更(geng)多寶貴(gui)的 PCB 面積。

　　典(dian)型的電(dian)池(chi)充電(dian)器 IC 需(xu)要恒定 DC 輸入電(dian)壓(ya)，而且不能(neng)(neng)處(chu)理能(neng)(neng)量突(tu)發。不過，諸(zhu)如(ru)室內光(guang)伏陣列或壓(ya)電(dian)換能(neng)(neng)器等斷續性能(neng)(neng)量收集電(dian)源提供的是功率(lv)突(tu)發。要用這類能(neng)(neng)源給(gei)電(dian)池(chi)充電(dian)，一個靜(jing)態(tai)工作電(dian)流低于 1uA 的獨(du)特 IC 是必需(xu)的。

　　鋰(li)離(li)子(zi) / 聚合物化(hua)學組成(cheng)的電(dian)(dian)池提(ti)供便攜式(shi)電(dian)(dian)子(zi)設備必需的高(gao)性能，但(dan)是(shi)這類(lei)電(dian)(dian)池必須(xu)小心使(shi)用。例(li)如，如果用比建議浮(fu)置電(dian)(dian)壓(ya)高(gao) 100mV 的電(dian)(dian)壓(ya)充電(dian)(dian)，鋰(li)離(li)子(zi) / 聚合物電(dian)(dian)池可能變得不(bu)穩定。此(ci)外，高(gao)壓(ya)和高(gao)溫(wen)同時存在(zai)(zai)會對電(dian)(dian)池壽命產(chan)生有害(hai)影響，而且在(zai)(zai)極端情況下，可能導(dao)致電(dian)(dian)池自毀。就幣形(xing)電(dian)(dian)池和薄膜電(dian)(dian)池而言，除(chu)了高(gao)溫(wen)和高(gao)壓(ya)同時存在(zai)(zai)可能產(chan)生有害(hai)影響，還有容量問題，因為它們的外形(xing)尺寸(cun)很小。

　　并(bing)聯(lian)架(jia)構的基(ji)本要素和好處

　　并(bing)聯基準(zhun)是電流饋送型、兩端子電路(lu)，在達到目標電壓之前不吸(xi)取電流。并(bing)聯基準(zhun)用起來(lai)像一個齊(qi)納(na)二極(ji)管，而且在電路(lu)原理(li)圖上常常顯示為一個齊(qi)納(na)二極(ji)管。不過，大(da)多(duo)數并(bing)聯基準(zhun)實際上都是基于帶隙基準(zhun)電壓的。

　　一個并聯基(ji)準僅需要(yao)(yao)單個外部電(dian)阻器來調節輸(shu)出電(dian)壓(ya)，從而極其容易使用。沒有最(zui)高輸(shu)入電(dian)壓(ya)限制(zhi)，最(zui)低輸(shu)入電(dian)壓(ya)由基(ji)準電(dian)壓(ya)值設定，因為需要(yao)(yao)一些(xie)空(kong)間(jian)以正(zheng)常運行(xing)。

　　此外(wai)，并聯基準(zhun)在(zai)寬電流(liu)范圍內有(you)良好的(de)穩定性(xing)。很多并聯基準(zhun)在(zai)有(you)大型(xing)或小(xiao)型(xing)容性(xing)負載時(shi)都(dou)是穩定的(de)。

　　滿足前述電池充電器 IC 設計限制的任何解決(jue)方案都必須兼有如下特(te)性：并聯(lian)穩壓器(qi)的特(te)性;能用低(di)功率連續或(huo)斷續性電(dian)(dian)(dian)源充(chong)電(dian)(dian)(dian)的電(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian) IC 的特(te)性。這樣的器(qi)件(jian)還(huan)需要保護鋰離子/聚(ju)合(he)物(wu)電(dian)(dian)(dian)池(chi)、幣(bi)形電(dian)(dian)(dian)池(chi)、薄膜電(dian)(dian)(dian)池(chi)或(huo)電(dian)(dian)(dian)池(chi)組的安全，并使電(dian)(dian)(dian)池(chi)或(huo)電(dian)(dian)(dian)池(chi)組達到最高性能。

　　凌力爾特開發了業界第一(yi)款(kuan)并聯(lian)(lian)(lian)架構電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi) LTC4070 和 LTC4071，以滿足這(zhe)類應(ying)用(yong)(yong)(yong)(yong)的(de)(de)需求。LTC4070 是一(yi)款(kuan)易用(yong)(yong)(yong)(yong)、纖巧的(de)(de)并聯(lian)(lian)(lian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)系統 IC，適(shi)用(yong)(yong)(yong)(yong)于鋰離子 / 聚(ju)合(he)物(wu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)、幣形電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)或薄(bo)膜(mo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)。該 IC 的(de)(de)工作電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流為 450nA，可(ke)保(bao)護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)，并可(ke)用(yong)(yong)(yong)(yong)以前(qian)不能(neng)使(shi)用(yong)(yong)(yong)(yong)的(de)(de)非(fei)常小電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)斷續性(xing)(xing)或連續性(xing)(xing)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源給這(zhe)些電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。增(zeng)加一(yi)個外部(bu) PMOS 并聯(lian)(lian)(lian)器(qi)(qi)件(jian)，LTC4070 的(de)(de)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流就(jiu)可(ke)以從 50mA 提高(gao)到 500mA。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)溫(wen)度(du)升高(gao)時，內(nei)部(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)熱量查驗器(qi)(qi)降低浮置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓，以保(bao)護鋰離子 / 聚(ju)合(he)物(wu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)安全。通過串(chuan)聯(lian)(lian)(lian)配(pei)置幾個 LTC4070，可(ke)以給由多節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)組(zu)成(cheng)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)組(zu)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并實現各節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)容量平衡。LTC4070 采用(yong)(yong)(yong)(yong)扁平 (0.75mm) 8 引線 2mm x 3mm DFN 封(feng)裝(zhuang)，僅用(yong)(yong)(yong)(yong)單個外部(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)器(qi)(qi) (要求與輸入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓串(chuan)聯(lian)(lian)(lian)) 就(jiu)能(neng)組(zu)成(cheng)一(yi)個完整(zheng)和超緊(jin)湊的(de)(de)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)解決方案。該器(qi)(qi)件(jian)的(de)(de)功能(neng)集(ji)使(shi)其非(fei)常適(shi)用(yong)(yong)(yong)(yong)于連續性(xing)(xing)和斷續性(xing)(xing)低功率充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源應(ying)用(yong)(yong)(yong)(yong)，包括鋰離子 / 聚(ju)合(he)物(wu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)備份(fen)、薄(bo)膜(mo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)、幣形電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)、存儲(chu)器(qi)(qi)備份(fen)、太陽能(neng)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)系統、嵌入式汽車和能(neng)量收集(ji)。

　　LTC4070提(ti)供引腳(jiao)可(ke)選的(de)(de) 4.0V、4.1V 和(he)(he) 4.2V 設(she)置，其準確度(du)為 1% 的(de)(de)電池(chi)(chi)(chi)浮置電壓(ya)允許(xu)用戶在電池(chi)(chi)(chi)能(neng)量(liang)密度(du)和(he)(he)壽命之(zhi)間(jian)進(jin)行(xing)取(qu)舍(she)。獨(du)立(li)的(de)(de)低電池(chi)(chi)(chi)電量(liang)和(he)(he)高電池(chi)(chi)(chi)電量(liang)監(jian)察狀態輸出指示(shi)放電或完全充電的(de)(de)電池(chi)(chi)(chi)。再加上(shang)一個與負載串聯的(de)(de)外部(bu) P-FET，該低電池(chi)(chi)(chi)電量(liang)狀態輸出可(ke)實現鎖斷(duan)功能(neng)，該功能(neng)自動斷(duan)接系統負載和(he)(he)電池(chi)(chi)(chi)，以防止電池(chi)(chi)(chi)深度(du)放電。

　　除了(le)緊湊的(de)(de) 2mm x 3mm 8 引線 DFN 封(feng)裝(zhuang)，LTC4070 還采用(yong) 8 引線 MSOP。這些器件(jian)規定在 -40?C 至 125?C 的(de)(de)溫(wen)度范(fan)圍內工作。

　　通過防(fang)止(zhi)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓超過設(she)定水平，LTC4070 提供(gong)了一個簡單、可靠、高性能(neng)的(de)電(dian)(dian)(dian)(dian)(dian)池(chi)保(bao)護(hu)和充電(dian)(dian)(dian)(dian)(dian)解決(jue)方(fang)案。其并聯架構在(zai)輸入(ru)電(dian)(dian)(dian)(dian)(dian)源和電(dian)(dian)(dian)(dian)(dian)池(chi)之間僅需要一個電(dian)(dian)(dian)(dian)(dian)阻器，就(jiu)可應對多種(zhong)電(dian)(dian)(dian)(dian)(dian)池(chi)應用(yong)。當輸入(ru)電(dian)(dian)(dian)(dian)(dian)源去掉，且電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓低于高的(de)電(dian)(dian)(dian)(dian)(dian)池(chi)輸出門限時，LTC4070 僅從電(dian)(dian)(dian)(dian)(dian)池(chi)吸取 450nA 電(dian)(dian)(dian)(dian)(dian)流。

　　當電(dian)(dian)池(chi)(chi)電(dian)(dian)壓低于設(she)定的浮置電(dian)(dian)壓時，充(chong)電(dian)(dian)速(su)率由輸(shu)入電(dian)(dian)壓、電(dian)(dian)池(chi)(chi)電(dian)(dian)壓和(he)輸(shu)入電(dian)(dian)阻器(qi)決定：

　　ICHG = (VIN ? VBAT) / RIN

　　當電(dian)(dian)(dian)池電(dian)(dian)(dian)壓(ya)(ya)接近浮置電(dian)(dian)(dian)壓(ya)(ya)時，LTC4070 從電(dian)(dian)(dian)池分(fen)走一部分(fen)電(dian)(dian)(dian)流，從而降低了充電(dian)(dian)(dian)電(dian)(dian)(dian)流。在整個溫度(du)范圍內(nei)變(bian)化浮置電(dian)(dian)(dian)壓(ya)(ya)的準確度(du)為 ±1% 時，LTC4070 可以(yi)分(fen)走高達 50mA 的電(dian)(dian)(dian)流。分(fen)流限制了最大充電(dian)(dian)(dian)電(dian)(dian)(dian)流，不(bu)過通過增加一個外部 P 溝(gou)道 MOSFET，50mA 的內(nei)部分(fen)流能(neng)力還(huan)可以(yi)提(ti)高，參見圖 1。

　　在(zai)內部(bu)，LTC4070 采用了一個由(you)放大器(qi) EA (參(can)見圖(tu) 2) 驅動的(de) P 溝道(dao) MOSFET。VCC 和 GND 之(zhi)間(jian)的(de)電(dian)壓(ya)達(da)到(dao) VF (即(ji)并聯電(dian)壓(ya)) 之(zhi)前，流(liu)經該(gai)器(qi)件的(de)電(dian)流(liu)為(wei)零。VF 可以(yi)由(you) ADJ 和 NTC 改變，但始終在(zai) 3.8V 到(dao) 4.2V 之(zhi)間(jian)。如果(guo) VCC 電(dian)壓(ya)低于這個值，那(nei)么 PFET 中(zhong)的(de)電(dian)流(liu)為(wei)零。如果(guo) VCC電(dian)壓(ya)試(shi)圖(tu)上升到(dao)超過 VF，那(nei)么電(dian)流(liu)將(jiang)流(liu)過該(gai)器(qi)件，以(yi)防止電(dian)壓(ya)上升，這就是(shi)分流(liu)。

　　工作電(dian)流(liu)是給(gei)該芯片中其余所有電(dian)路供電(dian)所需的電(dian)流(liu)。如果不存在外部電(dian)源，那么(me)這就是從電(dian)池吸取的電(dian)流(liu)。

　　當電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓低時(shi)(shi)，更多的電(dian)(dian)(dian)(dian)(dian)壓加在輸入電(dian)(dian)(dian)(dian)(dian)阻(zu)器(qi)兩端(duan)，因此進入電(dian)(dian)(dian)(dian)(dian)池(chi)的電(dian)(dian)(dian)(dian)(dian)流(liu) (即充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)) 略大于電(dian)(dian)(dian)(dian)(dian)池(chi)完全充電(dian)(dian)(dian)(dian)(dian)時(shi)(shi)的電(dian)(dian)(dian)(dian)(dian)流(liu)。當電(dian)(dian)(dian)(dian)(dian)池(chi)充滿電(dian)(dian)(dian)(dian)(dian)時(shi)(shi)，將(jiang)沒有電(dian)(dian)(dian)(dian)(dian)流(liu)進入電(dian)(dian)(dian)(dian)(dian)池(chi)，所有的輸入電(dian)(dian)(dian)(dian)(dian)流(liu)都將(jiang)進入分流(liu)器(qi)。

　　工作電(dian)(dian)(dian)(dian)流(liu)(liu)很重(zhong)要，因為它給(gei)“實際”輸(shu)入(ru)電(dian)(dian)(dian)(dian)源(yuan)的(de)(de)電(dian)(dian)(dian)(dian)流(liu)(liu)能(neng)力(li)設定了一個低限(xian)制。顯(xian)然，一個僅有 100nA驅(qu)動(dong)能(neng)力(li)的(de)(de)輸(shu)入(ru)電(dian)(dian)(dian)(dian)源(yuan)不可(ke)能(neng)給(gei)采(cai)用 LTC4070 的(de)(de)電(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)。不過，如果有 1uA 的(de)(de)驅(qu)動(dong)能(neng)力(li)，就能(neng)剩(sheng)下(xia)少量(liang)電(dian)(dian)(dian)(dian)流(liu)(liu)去充(chong)電(dian)(dian)(dian)(dian)。如果能(neng)得到 10uA 的(de)(de)驅(qu)動(dong)能(neng)力(li)，那么該(gai)電(dian)(dian)(dian)(dian)流(liu)(liu) 90% 以(yi)上都可(ke)用于充(chong)電(dian)(dian)(dian)(dian)。

　　NTC 電池查驗(yan)電路保護電池

　　LTC4070 用一個通過熱量耦(ou)合到電(dian)池(chi)的負(fu)溫(wen)度(du)系(xi)數(shu)熱敏電(dian)阻測量電(dian)池(chi)溫(wen)度(du)。NTC 熱敏電(dian)阻的溫(wen)度(du)特性(xing)在電(dian)阻-溫(wen)度(du)轉(zhuan)換表(biao)中規定。在溫(wen)度(du)高于 40°C 以(yi)后(hou)，每上升(sheng) 10°C，內部 NTC 電(dian)路就降低一次(ci)浮置電(dian)壓，以(yi)防(fang)止電(dian)池(chi)過熱 (參見圖 3 以(yi)了解詳細(xi)信息)。

　　LTC4070 采(cai)用一個(ge)(ge)電(dian)阻值之(zhi)比(bi)來測量電(dian)池(chi)溫(wen)(wen)度。LTC4070 在 NTCBIAS 與 GND 引腳之(zhi)間布(bu)設了(le)一個(ge)(ge)具 4 個(ge)(ge)抽(chou)(chou)頭(tou)的(de)內(nei)部固定電(dian)阻分壓器。定期地將這些(xie)抽(chou)(chou)頭(tou)上的(de)電(dian)壓與 NTC 引腳上的(de)電(dian)壓進行(xing)比(bi)較，以測量電(dian)池(chi)溫(wen)(wen)度。為了(le)節(jie)省功率，通過以大約(yue)每 1.5s 一次的(de)頻度把 NTCBIAS 引腳偏置至 VCC 來定期測量電(dian)池(chi)溫(wen)(wen)度。

    LTC4070 具(ju)有(you)一(yi)(yi)個(ge)與 ADJ 引腳(jiao)(jiao)相(xiang)(xiang)連(lian)的內(nei)置三態(tai)(tai)解(jie)碼器，用(yong)以(yi)(yi)提供(gong) 3 種可(ke)(ke)編(bian)程浮(fu)(fu)(fu)置電(dian)(dian)壓(ya)(ya)：4.0V、4.1V、或(huo) 4.2V。當(dang) ADJ 引腳(jiao)(jiao)連(lian)接(jie)至 GND、浮(fu)(fu)(fu)置或(huo)連(lian)接(jie)至 VCC 時(shi)，浮(fu)(fu)(fu)置電(dian)(dian)壓(ya)(ya)將被分(fen)別設置為(wei) 4.0V、4.1V 或(huo) 4.2V。大約每 1.5s 對 ADJ 引腳(jiao)(jiao)的狀(zhuang)態(tai)(tai)進行一(yi)(yi)次采(cai)樣(yang)。當(dang) ADJ 引腳(jiao)(jiao)被采(cai)樣(yang)時(shi)，LTC4070 在其上施加一(yi)(yi)個(ge)相(xiang)(xiang)對較低(di)的阻(zu)抗電(dian)(dian)壓(ya)(ya)。這(zhe)種做法可(ke)(ke)以(yi)(yi)防止低(di)水(shui)平的電(dian)(dian)路板漏(lou)電(dian)(dian)流破(po)壞設定的浮(fu)(fu)(fu)置電(dian)(dian)壓(ya)(ya)。免除電(dian)(dian)阻(zu)器不僅縮減了解(jie)決方案的外形尺寸，而且還由(you)于(yu)無(wu)需使用(yong)大阻(zu)值的電(dian)(dian)阻(zu)器而降低(di)了靜態(tai)(tai)電(dian)(dian)流。

　　另外，該器(qi)件還具(ju)有(you)狀態輸(shu)(shu)(shu)出(chu)(chu)及發送(song)指示(shi)信(xin)號(hao)的(de)能力。高(gao)電(dian)池(chi)電(dian)量(liang)監視器(qi)輸(shu)(shu)(shu)出(chu)(chu) (HBO) 是一個高(gao)態有(you)效(xiao) CMOS 輸(shu)(shu)(shu)出(chu)(chu)，當(dang)(dang)電(dian)池(chi)充滿電(dian)且電(dian)流通(tong)過(guo)分(fen)路(lu)離開(kai) BAT 時，該輸(shu)(shu)(shu)出(chu)(chu)將發出(chu)(chu)指示(shi)信(xin)號(hao)。低電(dian)池(chi)電(dian)量(liang)監視器(qi)輸(shu)(shu)(shu)出(chu)(chu) (LBO) 也是一個高(gao)態有(you)效(xiao) CMOS 輸(shu)(shu)(shu)出(chu)(chu)，當(dang)(dang)電(dian)池(chi)放電(dian)至 3.2V 以下時，此(ci)輸(shu)(shu)(shu)出(chu)(chu)將發出(chu)(chu)對應(ying)的(de)指示(shi)信(xin)號(hao)。最后，外部驅動器(qi)輸(shu)(shu)(shu)出(chu)(chu)引(yin)腳 DRV 可連(lian)接至外部 P-FET 的(de)柵極以增加分(fen)路(lu)電(dian)流，從而滿足(zu)那些需要 50mA 以上(shang)充電(dian)電(dian)流 (最大 500mA) 的(de)應(ying)用。

　　LTC4071 集成(cheng)電池(chi)組(zu)保護(hu)功能(neng)

　　LTC4071 也是一(yi)個(ge)并(bing)聯電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)系統，而(er)且還是首款具有(you)集成型電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組保護功(gong)能 (包括低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)) 的(de)(de)(de)器(qi)件。相(xiang)(xiang)比于 LTC4070，LTC4071 的(de)(de)(de)不同之(zhi)處(chu)包括：其擁有(you)集成型電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組保護功(gong)能 (低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)) 、但充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)能力較(jiao)低(di) (50mA)、靜態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)較(jiao)高 (550nA) 、且不具備 LBO。對于避(bi)免低(di)電(dian)(dian)(dian)(dian)(dian)(dian)量電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)由(you)于自放電(dian)(dian)(dian)(dian)(dian)(dian)而(er)受損而(er)言，低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)是一(yi)種必(bi)需(xu)的(de)(de)(de)關(guan)鍵性(xing)功(gong)能。雖然 LTC4070 能夠利用 LBO 和一(yi)個(ge)外部 P-FET 來實現低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)功(gong)能，但該 IC 仍(reng)將(jiang)繼(ji)續從電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)消耗(hao)全部 IQ (約 0.5μA)。即使是如此之(zhi)小的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)漏電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)也會(hui)在(zai)一(yi)夜之(zhi)間導致低(di)電(dian)(dian)(dian)(dian)(dian)(dian)量電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)損壞。相(xiang)(xiang)反，LTC4071 集成了一(yi)個(ge)徹底的(de)(de)(de)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)功(gong)能，當(dang)斷(duan)接(jie)時(shi)，從電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)吸取的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)接(jie)近零 (在(zai)室溫時(shi) <1nA，在(zai) 125°C 時(shi) < 25nA)。為了在(zai) LTC4071 中(zhong)提供這(zhe)一(yi)功(gong)能，相(xiang)(xiang)應于 LTC4070 的(de)(de)(de) LBO 和 DRV 引腳被去掉了。參(can)見圖 4 以(yi)了解(jie)詳細信息。這(zhe)使 LTC4071 的(de)(de)(de)最大分(fen)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)固定為 50mA (LTC4070 是 50mA，但采用一(yi)個(ge)外部 FET，就能達到 500mA)，而(er)且將(jiang)該 IC 的(de)(de)(de)靜態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)提高到了 550nA (LTC4070 的(de)(de)(de)靜態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)為 450nA)。下表 1 總結了這(zhe)兩個(ge)相(xiang)(xiang)互關(guan)聯的(de)(de)(de) IC 之(zhi)間的(de)(de)(de)差別(bie)。

　　結論

　　并聯(lian)(lian)基準有很多應用(yong)，而且視其功(gong)能的(de)(de)不(bu)同而不(bu)同，并聯(lian)(lian)基準甚至可(ke)以(yi)(yi)用(yong)來給電(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)。不(bu)過，這(zhe)種類型的(de)(de)應用(yong)有很多缺點，包(bao)括大靜態電(dian)(dian)流和(he)缺乏電(dian)(dian)池(chi)(chi)保護功(gong)能。現(xian)在，有了(le)合適的(de)(de) DC-DC 轉(zhuan)換器(qi)或電(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)器(qi)，因此(ci)可(ke)以(yi)(yi)對低功(gong)率能量收集(ji)應用(yong)進(jin)行(xing)查驗了(le)。凌(ling)力爾(er)特公司開發了(le) LTC4070 和(he) LTC4071 并聯(lian)(lian)充(chong)電(dian)(dian)器(qi)系(xi)統，這(zhe)兩款器(qi)件適用(yong)于鋰(li)離子 / 聚合物電(dian)(dian)池(chi)(chi)、幣形電(dian)(dian)池(chi)(chi)、薄膜電(dian)(dian)池(chi)(chi)和(he)電(dian)(dian)池(chi)(chi)組，可(ke)為具有低功(gong)率電(dian)(dian)源(yuan)的(de)(de)領(ling)先應用(yong)提供(gong)一種簡單(dan)、有效的(de)(de)電(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)和(he)電(dian)(dian)池(chi)(chi)組保護解決方案。