在市場上，能量(liang)收(shou)集(ji)(ji)(ji) IC 剛剛進入最(zui)初(chu)采用階(jie)段。能量(liang)收(shou)集(ji)(ji)(ji) IC 可將適(shi)合的換能器輸出(chu)轉(zhuan)換成電流，用于電池(chi)充電器設(she)備。盡管能量(liang)收(shou)集(ji)(ji)(ji)自 2000 年初(chu)就已經出(chu)現了(le)，但是最(zui)近的技術發展才(cai)將能量(liang)收(shou)集(ji)(ji)(ji)推進到可商用的程度。在能量(liang)收(shou)集(ji)(ji)(ji)應(ying)用領域有很多(duo)機會(hui)，包括：

　　? 在更(geng)換電(dian)(dian)池不方便、不現(xian)實(shi)或危險的情況下(xia)，取代電(dian)(dian)池供電(dian)(dian)系(xi)統或給電(dian)(dian)池供電(dian)(dian)系(xi)統再充電(dian)(dian)

　　? 無(wu)需(xu)導線來(lai)供(gong)電或(huo)傳送數據

　　? 用智能無線傳感器(qi)網(wang)絡監視(shi)和(he)優化復雜的工(gong)業(ye)過程(cheng)、安裝在偏(pian)遠現(xian)場的設備(bei)、以及大樓的加熱和(he)冷(leng)卻系統

　　? 從工業過程、太陽能電池板、內燃機等收集(ji)否(fou)則會浪費(fei)掉的熱(re)量

　　? 各種不同的消費電子產品的附屬充電器

　　在這些(xie)應用(yong)(yong)中，有很多(duo)(duo)含(han)有固(gu)有的斷續或低功率電(dian)源。而且，有很多(duo)(duo)應用(yong)(yong)將需要(yao)給電(dian)池充(chong)電(dian)，以提供一(yi)個備份電(dian)源。

　　并聯電(dian)壓基準(zhun)簡(jian)單易用，已經出現很多(duo)年了，有(you)大量產品(pin)。不(bu)(bu)過，這類基準(zhun)不(bu)(bu)能(neng)有(you)效地給(gei)電(dian)池(chi)(chi)充電(dian)。要配(pei)置一(yi)個(ge)并聯電(dian)壓基準(zhun)以(yi)給(gei)電(dian)池(chi)(chi)有(you)效充電(dian)是極端(duan)復雜的。此外，用一(yi)個(ge)小電(dian)流電(dian)源(yuan)或一(yi)個(ge)斷續性能(neng)量收(shou)集電(dian)源(yuan)準(zhun)確和安全(quan)地給(gei)鋰(li)離子 / 聚合物、幣形電(dian)池(chi)(chi)或薄膜電(dian)池(chi)(chi)充電(dian)，一(yi)直(zhi)是難以(yi)實現的。

　　從(cong)電(dian)(dian)(dian)池(chi)(chi)方面來看，盡管技(ji)術(shu)已經(jing)改進(jin)了(le)，但是(shi)便攜式電(dian)(dian)(dian)子(zi)設備(bei)(bei)的電(dian)(dian)(dian)池(chi)(chi)或電(dian)(dian)(dian)池(chi)(chi)組(zu)仍然(ran)需(xu)要保護和查驗，以保持電(dian)(dian)(dian)池(chi)(chi)在(zai)最佳(jia)狀(zhuang)態(tai)運行(xing)。鋰離子(zi) / 聚合物電(dian)(dian)(dian)池(chi)(chi)技(ji)術(shu)已經(jing)成熟(shu)，是(shi)很多(duo)電(dian)(dian)(dian)子(zi)設備(bei)(bei)流行(xing)的電(dian)(dian)(dian)源選擇，因為這(zhe)類(lei)電(dian)(dian)(dian)池(chi)(chi)能(neng)量(liang)密(mi)度高(gao)、自放電(dian)(dian)(dian)很少、需(xu)要很少的維護、電(dian)(dian)(dian)壓范圍(wei)很寬(kuan)并(bing)具(ju)有(you)(you)其他一些特色。幣(bi)形電(dian)(dian)(dian)池(chi)(chi)能(neng)量(liang)密(mi)度高(gao)、放電(dian)(dian)(dian)特性穩定、重量(liang)輕且外形尺寸小(xiao)。薄膜電(dian)(dian)(dian)池(chi)(chi)是(shi)一種(zhong)新出現的技(ji)術(shu)，優勢是(shi)允許非常多(duo)的充電(dian)(dian)(dian)周期次數，并(bing)具(ju)有(you)(you)物理靈活(huo)性，即視(shi)最終應用(yong)的不同而不同，薄膜電(dian)(dian)(dian)池(chi)(chi)可以做(zuo)成幾乎(hu)任何形狀(zhuang)。不過，如果不能(neng)正確充電(dian)(dian)(dian)和查驗，那(nei)么所有(you)(you)這(zhe)些類(lei)型(xing)的電(dian)(dian)(dian)池(chi)(chi)都可能(neng)受(shou)到一些有(you)(you)害影(ying)響。

　　低(di)功耗(hao)充(chong)電器的設計挑戰(zhan)

　　可(ke)(ke)調(diao)并聯基準可(ke)(ke)被(bei)設(she)定以提供恰當的(de)(de)(de)電(dian)(dian)(dian)池(chi)浮置電(dian)(dian)(dian)壓(ya)，但是(shi)這類基準缺乏電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)器(qi)的(de)(de)(de) NTC 功能(neng)。更重(zhong)要的(de)(de)(de)是(shi)，所需的(de)(de)(de)工作電(dian)(dian)(dian)流太(tai)高了，以至于(yu)用低功率電(dian)(dian)(dian)源(yuan)或斷續性電(dian)(dian)(dian)源(yuan)給電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)是(shi)不(bu)現實的(de)(de)(de)。或者，可(ke)(ke)以用一個齊(qi)納二(er)極管、一些電(dian)(dian)(dian)阻器(qi)、一個 NPN 晶體管和一些比較(jiao)器(qi)構成一個分(fen)(fen)立式并聯基準，以提供 NTC 功能(neng)。不(bu)過(guo)，這樣(yang)的(de)(de)(de)并聯基準仍(reng)然受(shou)到前述(shu)限制。此外，分(fen)(fen)立式并聯基準實現起(qi)來比較(jiao)復雜(za)，相比之下，會占用更多(duo)寶貴的(de)(de)(de) PCB 面積。

　　典型(xing)的(de)電池充電器 IC 需(xu)要恒定(ding) DC 輸(shu)入(ru)電壓，而且不(bu)(bu)能處理能量突發。不(bu)(bu)過，諸(zhu)如室內光伏陣列(lie)或(huo)壓電換能器等斷續性能量收集電源提供(gong)的(de)是功(gong)率突發。要用這(zhe)類能源給(gei)電池充電，一個(ge)靜(jing)態工(gong)作電流低(di)于 1uA 的(de)獨(du)特 IC 是必需(xu)的(de)。

　　鋰離子(zi) / 聚合(he)物化學(xue)組成(cheng)的(de)(de)電池(chi)提供便攜式電子(zi)設備(bei)必需(xu)的(de)(de)高(gao)性能(neng)(neng)，但是這類電池(chi)必須小心使用(yong)。例如，如果用(yong)比建議(yi)浮(fu)置(zhi)電壓高(gao) 100mV 的(de)(de)電壓充(chong)電，鋰離子(zi) / 聚合(he)物電池(chi)可(ke)(ke)能(neng)(neng)變得不穩定。此外(wai)，高(gao)壓和高(gao)溫同時(shi)(shi)存(cun)在會對電池(chi)壽命產生有(you)害(hai)影響(xiang)，而(er)且(qie)在極端情況下，可(ke)(ke)能(neng)(neng)導致電池(chi)自毀。就幣(bi)形(xing)電池(chi)和薄膜(mo)電池(chi)而(er)言，除了高(gao)溫和高(gao)壓同時(shi)(shi)存(cun)在可(ke)(ke)能(neng)(neng)產生有(you)害(hai)影響(xiang)，還有(you)容量(liang)問題，因為它們(men)的(de)(de)外(wai)形(xing)尺寸(cun)很小。

　　并聯(lian)架構的基本要素和好處(chu)

　　并聯基準(zhun)(zhun)是(shi)電流饋送型、兩端(duan)子電路，在達到目標電壓之前不(bu)吸取電流。并聯基準(zhun)(zhun)用起來像一個(ge)齊納二極管，而且在電路原理圖上常常顯示為一個(ge)齊納二極管。不(bu)過，大多(duo)數并聯基準(zhun)(zhun)實際上都(dou)是(shi)基于帶隙基準(zhun)(zhun)電壓的。

　　一(yi)(yi)個并聯基準僅(jin)需要單個外部電(dian)阻器來調(diao)節輸(shu)出電(dian)壓(ya)，從而極其容(rong)易使用。沒有(you)最高輸(shu)入電(dian)壓(ya)限(xian)制，最低輸(shu)入電(dian)壓(ya)由基準電(dian)壓(ya)值設定，因為需要一(yi)(yi)些空間以正常(chang)運行。

　　此外，并聯基(ji)準(zhun)在(zai)寬電流范圍內有良好(hao)的穩定(ding)性。很多并聯基(ji)準(zhun)在(zai)有大型或小型容性負(fu)載時都(dou)是穩定(ding)的。

　　滿足前述電池充電器 IC 設計限(xian)制的(de)(de)(de)(de)任何解決方案都必須兼有如下特性(xing)(xing)(xing)(xing)：并聯穩壓(ya)器的(de)(de)(de)(de)特性(xing)(xing)(xing)(xing);能用低功率連續或(huo)斷(duan)續性(xing)(xing)(xing)(xing)電(dian)(dian)源充電(dian)(dian)的(de)(de)(de)(de)電(dian)(dian)池(chi)(chi)(chi)(chi)充電(dian)(dian) IC 的(de)(de)(de)(de)特性(xing)(xing)(xing)(xing)。這樣的(de)(de)(de)(de)器件還(huan)需要保(bao)護鋰離子/聚合(he)物電(dian)(dian)池(chi)(chi)(chi)(chi)、幣(bi)形電(dian)(dian)池(chi)(chi)(chi)(chi)、薄膜電(dian)(dian)池(chi)(chi)(chi)(chi)或(huo)電(dian)(dian)池(chi)(chi)(chi)(chi)組(zu)的(de)(de)(de)(de)安全，并使電(dian)(dian)池(chi)(chi)(chi)(chi)或(huo)電(dian)(dian)池(chi)(chi)(chi)(chi)組(zu)達到(dao)最高性(xing)(xing)(xing)(xing)能。

　　凌力爾(er)特開發(fa)了業界第一款(kuan)并(bing)(bing)(bing)聯(lian)(lian)(lian)架構(gou)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi) LTC4070 和 LTC4071，以(yi)(yi)滿足這(zhe)類(lei)應用(yong)(yong)(yong)的(de)(de)(de)(de)需求(qiu)(qiu)。LTC4070 是(shi)一款(kuan)易用(yong)(yong)(yong)、纖巧的(de)(de)(de)(de)并(bing)(bing)(bing)聯(lian)(lian)(lian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)系(xi)統 IC，適用(yong)(yong)(yong)于(yu)(yu)鋰離(li)子(zi) / 聚合物電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)、幣形(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)或薄(bo)膜電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)。該 IC 的(de)(de)(de)(de)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)為 450nA，可(ke)保護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)，并(bing)(bing)(bing)可(ke)用(yong)(yong)(yong)以(yi)(yi)前不能(neng)使用(yong)(yong)(yong)的(de)(de)(de)(de)非常小電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)斷續(xu)(xu)性(xing)或連(lian)續(xu)(xu)性(xing)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源給這(zhe)些電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。增加一個(ge)外(wai)部 PMOS 并(bing)(bing)(bing)聯(lian)(lian)(lian)器(qi)(qi)(qi)(qi)件，LTC4070 的(de)(de)(de)(de)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)就(jiu)可(ke)以(yi)(yi)從 50mA 提高(gao)到(dao) 500mA。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)溫度升高(gao)時(shi)，內部電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)熱量查驗器(qi)(qi)(qi)(qi)降(jiang)低(di)(di)浮置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓，以(yi)(yi)保護鋰離(li)子(zi) / 聚合物電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)安全。通(tong)過串(chuan)聯(lian)(lian)(lian)配(pei)置幾(ji)個(ge) LTC4070，可(ke)以(yi)(yi)給由多節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)成的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組(zu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并(bing)(bing)(bing)實現各(ge)節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)容量平衡。LTC4070 采用(yong)(yong)(yong)扁平 (0.75mm) 8 引(yin)線 2mm x 3mm DFN 封裝，僅用(yong)(yong)(yong)單個(ge)外(wai)部電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻器(qi)(qi)(qi)(qi) (要求(qiu)(qiu)與輸入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓串(chuan)聯(lian)(lian)(lian)) 就(jiu)能(neng)組(zu)成一個(ge)完整(zheng)和超緊湊的(de)(de)(de)(de)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)解決(jue)方案。該器(qi)(qi)(qi)(qi)件的(de)(de)(de)(de)功能(neng)集使其非常適用(yong)(yong)(yong)于(yu)(yu)連(lian)續(xu)(xu)性(xing)和斷續(xu)(xu)性(xing)低(di)(di)功率充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源應用(yong)(yong)(yong)，包括鋰離(li)子(zi) / 聚合物電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)備份(fen)、薄(bo)膜電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)、幣形(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)、存儲(chu)器(qi)(qi)(qi)(qi)備份(fen)、太陽能(neng)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)系(xi)統、嵌入(ru)(ru)式汽車和能(neng)量收集。

　　LTC4070提供(gong)引腳(jiao)可選的 4.0V、4.1V 和(he) 4.2V 設置(zhi)，其準確度為 1% 的電(dian)(dian)(dian)(dian)池(chi)(chi)浮置(zhi)電(dian)(dian)(dian)(dian)壓允許用戶(hu)在電(dian)(dian)(dian)(dian)池(chi)(chi)能量(liang)密度和(he)壽命(ming)之間進(jin)行取舍。獨立的低電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)量(liang)和(he)高電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)量(liang)監察狀態輸(shu)出(chu)指示放電(dian)(dian)(dian)(dian)或(huo)完全充電(dian)(dian)(dian)(dian)的電(dian)(dian)(dian)(dian)池(chi)(chi)。再加上(shang)一個與負(fu)載(zai)串(chuan)聯的外部 P-FET，該(gai)(gai)低電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)量(liang)狀態輸(shu)出(chu)可實現(xian)鎖斷(duan)功能，該(gai)(gai)功能自動斷(duan)接系統負(fu)載(zai)和(he)電(dian)(dian)(dian)(dian)池(chi)(chi)，以防止電(dian)(dian)(dian)(dian)池(chi)(chi)深度放電(dian)(dian)(dian)(dian)。

　　除(chu)了緊湊(cou)的(de) 2mm x 3mm 8 引線 DFN 封裝，LTC4070 還采(cai)用 8 引線 MSOP。這些器件規(gui)定在 -40?C 至 125?C 的(de)溫度范(fan)圍(wei)內(nei)工(gong)作。

　　通過防止電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)壓超(chao)過設定水平(ping)，LTC4070 提供了(le)一(yi)個簡單(dan)、可靠、高性能的電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)保(bao)護和充電(dian)(dian)(dian)(dian)(dian)解決(jue)方(fang)案。其并聯(lian)架構在輸(shu)入電(dian)(dian)(dian)(dian)(dian)源和電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)之間僅需要一(yi)個電(dian)(dian)(dian)(dian)(dian)阻(zu)器，就可應(ying)對多(duo)種(zhong)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)應(ying)用。當輸(shu)入電(dian)(dian)(dian)(dian)(dian)源去(qu)掉(diao)，且電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)壓低(di)于高的電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)輸(shu)出(chu)門(men)限時，LTC4070 僅從電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)吸取 450nA 電(dian)(dian)(dian)(dian)(dian)流(liu)。

　　當(dang)電(dian)(dian)池(chi)(chi)電(dian)(dian)壓(ya)低(di)于設定的(de)浮置(zhi)電(dian)(dian)壓(ya)時(shi)，充電(dian)(dian)速(su)率由(you)輸入(ru)電(dian)(dian)壓(ya)、電(dian)(dian)池(chi)(chi)電(dian)(dian)壓(ya)和(he)輸入(ru)電(dian)(dian)阻器決定：

　　ICHG = (VIN ? VBAT) / RIN

　　當(dang)電(dian)(dian)池電(dian)(dian)壓(ya)(ya)接近(jin)浮置電(dian)(dian)壓(ya)(ya)時(shi)，LTC4070 從電(dian)(dian)池分(fen)走一部(bu)分(fen)電(dian)(dian)流(liu)(liu)(liu)，從而降低了(le)充電(dian)(dian)電(dian)(dian)流(liu)(liu)(liu)。在整個溫度范圍(wei)內變(bian)化(hua)浮置電(dian)(dian)壓(ya)(ya)的準(zhun)確度為 ±1% 時(shi)，LTC4070 可以(yi)分(fen)走高(gao)達(da) 50mA 的電(dian)(dian)流(liu)(liu)(liu)。分(fen)流(liu)(liu)(liu)限制了(le)最大(da)充電(dian)(dian)電(dian)(dian)流(liu)(liu)(liu)，不過(guo)通(tong)過(guo)增(zeng)加一個外部(bu) P 溝道 MOSFET，50mA 的內部(bu)分(fen)流(liu)(liu)(liu)能力還可以(yi)提高(gao)，參(can)見圖 1。

　　在內部，LTC4070 采用了一個(ge)(ge)由(you)放大(da)器 EA (參見圖 2) 驅(qu)動的(de)(de) P 溝道 MOSFET。VCC 和 GND 之間的(de)(de)電壓(ya)達到(dao) VF (即(ji)并聯電壓(ya)) 之前，流經該(gai)器件的(de)(de)電流為零(ling)。VF 可以由(you) ADJ 和 NTC 改(gai)變(bian)，但始終在 3.8V 到(dao) 4.2V 之間。如果(guo) VCC 電壓(ya)低于這(zhe)個(ge)(ge)值，那么(me)(me) PFET 中的(de)(de)電流為零(ling)。如果(guo) VCC電壓(ya)試(shi)圖上升(sheng)到(dao)超過 VF，那么(me)(me)電流將流過該(gai)器件，以防(fang)止電壓(ya)上升(sheng)，這(zhe)就是分(fen)流。

　　工(gong)作電(dian)(dian)流是(shi)給該芯片中其余所有電(dian)(dian)路供電(dian)(dian)所需的電(dian)(dian)流。如果不存在(zai)外部電(dian)(dian)源，那么(me)這就是(shi)從(cong)電(dian)(dian)池吸取的電(dian)(dian)流。

　　當電(dian)(dian)池(chi)(chi)電(dian)(dian)壓低時(shi)，更多的電(dian)(dian)壓加在輸入(ru)電(dian)(dian)阻器兩端，因此進(jin)入(ru)電(dian)(dian)池(chi)(chi)的電(dian)(dian)流 (即充(chong)電(dian)(dian)電(dian)(dian)流) 略(lve)大于電(dian)(dian)池(chi)(chi)完全充(chong)電(dian)(dian)時(shi)的電(dian)(dian)流。當電(dian)(dian)池(chi)(chi)充(chong)滿(man)電(dian)(dian)時(shi)，將(jiang)沒(mei)有(you)電(dian)(dian)流進(jin)入(ru)電(dian)(dian)池(chi)(chi)，所(suo)有(you)的輸入(ru)電(dian)(dian)流都將(jiang)進(jin)入(ru)分流器。

　　工作電(dian)(dian)流很重要，因為(wei)它給“實際(ji)”輸入電(dian)(dian)源(yuan)的(de)電(dian)(dian)流能(neng)(neng)力設定了一個低限制。顯然，一個僅有(you) 100nA驅(qu)(qu)動能(neng)(neng)力的(de)輸入電(dian)(dian)源(yuan)不可能(neng)(neng)給采用 LTC4070 的(de)電(dian)(dian)池充(chong)電(dian)(dian)。不過(guo)，如果有(you) 1uA 的(de)驅(qu)(qu)動能(neng)(neng)力，就能(neng)(neng)剩(sheng)下(xia)少(shao)量電(dian)(dian)流去(qu)充(chong)電(dian)(dian)。如果能(neng)(neng)得(de)到 10uA 的(de)驅(qu)(qu)動能(neng)(neng)力，那么(me)該電(dian)(dian)流 90% 以上(shang)都(dou)可用于充(chong)電(dian)(dian)。

　　NTC 電池(chi)查(cha)驗(yan)電路(lu)保護電池(chi)

　　LTC4070 用(yong)一(yi)個通過熱(re)(re)量(liang)耦合(he)到電(dian)池(chi)(chi)的(de)負溫(wen)度(du)(du)系(xi)數熱(re)(re)敏電(dian)阻(zu)測量(liang)電(dian)池(chi)(chi)溫(wen)度(du)(du)。NTC 熱(re)(re)敏電(dian)阻(zu)的(de)溫(wen)度(du)(du)特性在電(dian)阻(zu)-溫(wen)度(du)(du)轉換表中規定。在溫(wen)度(du)(du)高(gao)于(yu) 40°C 以后，每上升(sheng) 10°C，內部 NTC 電(dian)路就(jiu)降低(di)一(yi)次浮置電(dian)壓，以防止電(dian)池(chi)(chi)過熱(re)(re) (參見圖 3 以了解(jie)詳細信(xin)息)。

　　LTC4070 采(cai)用一(yi)個電(dian)阻值之比來(lai)測(ce)量電(dian)池溫(wen)(wen)度(du)。LTC4070 在 NTCBIAS 與 GND 引(yin)腳之間布設了一(yi)個具 4 個抽(chou)頭的(de)內部固定(ding)電(dian)阻分壓器。定(ding)期地將這些抽(chou)頭上(shang)的(de)電(dian)壓與 NTC 引(yin)腳上(shang)的(de)電(dian)壓進行(xing)比較，以(yi)(yi)測(ce)量電(dian)池溫(wen)(wen)度(du)。為了節省功率，通(tong)過以(yi)(yi)大約每 1.5s 一(yi)次的(de)頻(pin)度(du)把 NTCBIAS 引(yin)腳偏置至 VCC 來(lai)定(ding)期測(ce)量電(dian)池溫(wen)(wen)度(du)。

    LTC4070 具(ju)有(you)一(yi)個(ge)與(yu) ADJ 引(yin)腳相(xiang)連的(de)(de)內(nei)置(zhi)三態(tai)解(jie)碼器(qi)，用以(yi)提供(gong) 3 種可(ke)編程浮(fu)置(zhi)電(dian)壓：4.0V、4.1V、或(huo)(huo) 4.2V。當(dang)(dang) ADJ 引(yin)腳連接至(zhi) GND、浮(fu)置(zhi)或(huo)(huo)連接至(zhi) VCC 時，浮(fu)置(zhi)電(dian)壓將被(bei)分別設置(zhi)為 4.0V、4.1V 或(huo)(huo) 4.2V。大約每 1.5s 對 ADJ 引(yin)腳的(de)(de)狀態(tai)進行一(yi)次采(cai)樣。當(dang)(dang) ADJ 引(yin)腳被(bei)采(cai)樣時，LTC4070 在(zai)其(qi)上施加一(yi)個(ge)相(xiang)對較低(di)的(de)(de)阻(zu)抗電(dian)壓。這種做法(fa)可(ke)以(yi)防止低(di)水平的(de)(de)電(dian)路板漏電(dian)流(liu)破壞設定的(de)(de)浮(fu)置(zhi)電(dian)壓。免(mian)除電(dian)阻(zu)器(qi)不僅縮減了解(jie)決方(fang)案的(de)(de)外形(xing)尺寸，而(er)且還由于無需使用大阻(zu)值的(de)(de)電(dian)阻(zu)器(qi)而(er)降(jiang)低(di)了靜態(tai)電(dian)流(liu)。

　　另外(wai)，該(gai)器件還具有(you)狀態輸(shu)出(chu)及(ji)發(fa)(fa)送指示(shi)(shi)信號的(de)能力。高(gao)電(dian)(dian)池(chi)(chi)電(dian)(dian)量(liang)監視器輸(shu)出(chu) (HBO) 是一個高(gao)態有(you)效(xiao) CMOS 輸(shu)出(chu)，當電(dian)(dian)池(chi)(chi)充滿(man)電(dian)(dian)且電(dian)(dian)流(liu)(liu)通過分(fen)路離(li)開 BAT 時，該(gai)輸(shu)出(chu)將發(fa)(fa)出(chu)指示(shi)(shi)信號。低電(dian)(dian)池(chi)(chi)電(dian)(dian)量(liang)監視器輸(shu)出(chu) (LBO) 也(ye)是一個高(gao)態有(you)效(xiao) CMOS 輸(shu)出(chu)，當電(dian)(dian)池(chi)(chi)放(fang)電(dian)(dian)至(zhi) 3.2V 以(yi)下時，此輸(shu)出(chu)將發(fa)(fa)出(chu)對應的(de)指示(shi)(shi)信號。最后，外(wai)部(bu)驅(qu)動器輸(shu)出(chu)引腳 DRV 可連接至(zhi)外(wai)部(bu) P-FET 的(de)柵極以(yi)增加分(fen)路電(dian)(dian)流(liu)(liu)，從而滿(man)足那些需要 50mA 以(yi)上充電(dian)(dian)電(dian)(dian)流(liu)(liu) (最大 500mA) 的(de)應用。

　　LTC4071 集成電池組保護功能

　　LTC4071 也是(shi)(shi)(shi)一(yi)個(ge)并聯(lian)電(dian)(dian)(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)(dian)(dian)器系統(tong)，而(er)且還是(shi)(shi)(shi)首(shou)款具(ju)有集成(cheng)型電(dian)(dian)(dian)(dian)(dian)(dian)池組保(bao)護功能 (包括(kuo)低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)(jie)) 的(de)(de)(de)(de)器件。相比于(yu)(yu)(yu) LTC4070，LTC4071 的(de)(de)(de)(de)不同之處(chu)包括(kuo)：其(qi)擁(yong)有集成(cheng)型電(dian)(dian)(dian)(dian)(dian)(dian)池組保(bao)護功能 (低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)(jie)) 、但(dan)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)能力較(jiao)低(di)(di) (50mA)、靜態電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)較(jiao)高 (550nA) 、且不具(ju)備 LBO。對于(yu)(yu)(yu)避免低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)量電(dian)(dian)(dian)(dian)(dian)(dian)池由(you)于(yu)(yu)(yu)自放電(dian)(dian)(dian)(dian)(dian)(dian)而(er)受損而(er)言，低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)(jie)是(shi)(shi)(shi)一(yi)種必需的(de)(de)(de)(de)關鍵性功能。雖然 LTC4070 能夠(gou)利(li)用 LBO 和(he)一(yi)個(ge)外部(bu)(bu)(bu) P-FET 來實現低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)(jie)功能，但(dan)該(gai)(gai) IC 仍(reng)將(jiang)繼續從電(dian)(dian)(dian)(dian)(dian)(dian)池消耗全部(bu)(bu)(bu) IQ (約 0.5μA)。即使(shi)是(shi)(shi)(shi)如此之小的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池漏電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)也會(hui)在(zai)一(yi)夜之間導致(zhi)低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)量電(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)(de)損壞。相反，LTC4071 集成(cheng)了(le)(le)一(yi)個(ge)徹(che)底的(de)(de)(de)(de)低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)量斷(duan)接(jie)(jie)功能，當(dang)斷(duan)接(jie)(jie)時(shi)，從電(dian)(dian)(dian)(dian)(dian)(dian)池吸取的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)接(jie)(jie)近零 (在(zai)室(shi)溫時(shi) <1nA，在(zai) 125°C 時(shi) < 25nA)。為(wei)了(le)(le)在(zai) LTC4071 中提(ti)供這(zhe)(zhe)一(yi)功能，相應于(yu)(yu)(yu) LTC4070 的(de)(de)(de)(de) LBO 和(he) DRV 引腳被去(qu)掉了(le)(le)。參(can)見(jian)圖 4 以了(le)(le)解(jie)詳細信息。這(zhe)(zhe)使(shi) LTC4071 的(de)(de)(de)(de)最大(da)分流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)固定(ding)為(wei) 50mA (LTC4070 是(shi)(shi)(shi) 50mA，但(dan)采用一(yi)個(ge)外部(bu)(bu)(bu) FET，就能達到 500mA)，而(er)且將(jiang)該(gai)(gai) IC 的(de)(de)(de)(de)靜態電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)提(ti)高到了(le)(le) 550nA (LTC4070 的(de)(de)(de)(de)靜態電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)為(wei) 450nA)。下(xia)表 1 總結了(le)(le)這(zhe)(zhe)兩(liang)個(ge)相互關聯(lian)的(de)(de)(de)(de) IC 之間的(de)(de)(de)(de)差別。

　　結論

　　并(bing)聯(lian)基準有很多應用(yong)，而(er)且視其功能(neng)的不同而(er)不同，并(bing)聯(lian)基準甚(shen)至(zhi)可以用(yong)來給電池充電。不過，這(zhe)(zhe)種(zhong)類(lei)型(xing)的應用(yong)有很多缺點，包(bao)括大靜態電流和(he)(he)缺乏電池保護功能(neng)。現在，有了合適的 DC-DC 轉換器(qi)或電池充電器(qi)，因此可以對低(di)功率(lv)能(neng)量收(shou)集應用(yong)進行查驗了。凌力爾特公(gong)司開發了 LTC4070 和(he)(he) LTC4071 并(bing)聯(lian)充電器(qi)系統，這(zhe)(zhe)兩款(kuan)器(qi)件(jian)適用(yong)于鋰離子 / 聚合物電池、幣形電池、薄膜電池和(he)(he)電池組(zu)，可為具有低(di)功率(lv)電源的領先應用(yong)提供(gong)一種(zhong)簡單、有效的電池充電和(he)(he)電池組(zu)保護解決方案。