在市場(chang)上，能(neng)量(liang)收(shou)集(ji) IC 剛剛進(jin)(jin)入最初采用(yong)階段(duan)。能(neng)量(liang)收(shou)集(ji) IC 可(ke)將適(shi)合(he)的換能(neng)器(qi)輸出轉換成電(dian)流，用(yong)于電(dian)池充電(dian)器(qi)設備。盡管能(neng)量(liang)收(shou)集(ji)自 2000 年初就已經(jing)出現了，但是(shi)最近的技(ji)術發展才(cai)將能(neng)量(liang)收(shou)集(ji)推進(jin)(jin)到可(ke)商(shang)用(yong)的程(cheng)度。在能(neng)量(liang)收(shou)集(ji)應用(yong)領域有很多機會(hui)，包括(kuo)：

　　? 在(zai)更(geng)換電(dian)(dian)(dian)池(chi)不方便(bian)、不現(xian)實或危險的情(qing)況(kuang)下，取代電(dian)(dian)(dian)池(chi)供(gong)電(dian)(dian)(dian)系統或給電(dian)(dian)(dian)池(chi)供(gong)電(dian)(dian)(dian)系統再(zai)充電(dian)(dian)(dian)

　　? 無需導線來供電或傳送數據(ju)

　　? 用智能無線傳感器(qi)網絡監視和優化復雜的(de)工業過(guo)程(cheng)、安裝(zhuang)在偏遠現場的(de)設備、以(yi)及大樓的(de)加熱(re)和冷卻系統

　　? 從工業過程、太陽能電池(chi)板、內燃(ran)機等收集否則會浪(lang)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(ying)用(yong)中，有(you)(you)(you)很(hen)多(duo)含有(you)(you)(you)固有(you)(you)(you)的斷續或低功率電(dian)源。而且，有(you)(you)(you)很(hen)多(duo)應(ying)用(yong)將需要(yao)給電(dian)池充電(dian)，以提(ti)供一個備份(fen)電(dian)源。

　　并聯電(dian)(dian)(dian)壓(ya)基準簡單易用，已經出現(xian)(xian)很多年了，有大(da)量產品。不過，這(zhe)類基準不能(neng)有效(xiao)地(di)給電(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)。要配置一(yi)個(ge)并聯電(dian)(dian)(dian)壓(ya)基準以給電(dian)(dian)(dian)池(chi)有效(xiao)充(chong)(chong)電(dian)(dian)(dian)是極端復雜的。此外(wai)，用一(yi)個(ge)小(xiao)電(dian)(dian)(dian)流電(dian)(dian)(dian)源或一(yi)個(ge)斷(duan)續性能(neng)量收(shou)集電(dian)(dian)(dian)源準確和安(an)全地(di)給鋰離子 / 聚合物、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(yi)直是難以實現(xian)(xian)的。

　　從電(dian)(dian)(dian)池(chi)(chi)方面來看，盡管(guan)技(ji)術已(yi)經改(gai)進了，但是便攜式電(dian)(dian)(dian)子設備的(de)電(dian)(dian)(dian)池(chi)(chi)或電(dian)(dian)(dian)池(chi)(chi)組(zu)仍然需要(yao)保護(hu)和查驗，以保持電(dian)(dian)(dian)池(chi)(chi)在最佳狀(zhuang)態(tai)運行(xing)。鋰離子 / 聚(ju)合物(wu)電(dian)(dian)(dian)池(chi)(chi)技(ji)術已(yi)經成熟，是很多電(dian)(dian)(dian)子設備流行(xing)的(de)電(dian)(dian)(dian)源選(xuan)擇，因為(wei)這類(lei)電(dian)(dian)(dian)池(chi)(chi)能量(liang)密度(du)高、自放(fang)電(dian)(dian)(dian)很少(shao)(shao)、需要(yao)很少(shao)(shao)的(de)維護(hu)、電(dian)(dian)(dian)壓范圍很寬并具有(you)其他一(yi)(yi)些(xie)特色。幣形(xing)電(dian)(dian)(dian)池(chi)(chi)能量(liang)密度(du)高、放(fang)電(dian)(dian)(dian)特性(xing)穩定、重(zhong)量(liang)輕(qing)且外形(xing)尺(chi)寸小。薄膜電(dian)(dian)(dian)池(chi)(chi)是一(yi)(yi)種新(xin)出現的(de)技(ji)術，優勢是允許非(fei)常(chang)多的(de)充電(dian)(dian)(dian)周期次數，并具有(you)物(wu)理靈(ling)活性(xing)，即視(shi)最終應用的(de)不同而不同，薄膜電(dian)(dian)(dian)池(chi)(chi)可以做成幾(ji)乎任何形(xing)狀(zhuang)。不過，如果不能正確充電(dian)(dian)(dian)和查驗，那么所有(you)這些(xie)類(lei)型的(de)電(dian)(dian)(dian)池(chi)(chi)都(dou)可能受到一(yi)(yi)些(xie)有(you)害影響。

　　低功(gong)耗充電器的設(she)計(ji)挑戰

　　可(ke)(ke)調(diao)并聯(lian)基(ji)(ji)準(zhun)可(ke)(ke)被設(she)定以(yi)提供恰當的(de)電(dian)(dian)(dian)池浮(fu)置(zhi)電(dian)(dian)(dian)壓，但是(shi)這類基(ji)(ji)準(zhun)缺乏電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)器(qi)(qi)的(de) NTC 功能。更重要的(de)是(shi)，所(suo)需(xu)的(de)工作電(dian)(dian)(dian)流太高(gao)了，以(yi)至于用低功率電(dian)(dian)(dian)源(yuan)或斷續性電(dian)(dian)(dian)源(yuan)給電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)是(shi)不現實的(de)。或者，可(ke)(ke)以(yi)用一個(ge)齊納二(er)極管、一些電(dian)(dian)(dian)阻器(qi)(qi)、一個(ge) NPN 晶體管和(he)一些比較(jiao)器(qi)(qi)構成(cheng)一個(ge)分立式(shi)并聯(lian)基(ji)(ji)準(zhun)，以(yi)提供 NTC 功能。不過，這樣的(de)并聯(lian)基(ji)(ji)準(zhun)仍然(ran)受到前述限制。此外，分立式(shi)并聯(lian)基(ji)(ji)準(zhun)實現起來比較(jiao)復(fu)雜，相比之下，會占用更多(duo)寶貴的(de) PCB 面積。

　　典型的(de)電(dian)池充電(dian)器 IC 需(xu)(xu)要恒(heng)定(ding) DC 輸入電(dian)壓，而(er)且(qie)不(bu)能(neng)(neng)處理能(neng)(neng)量突發(fa)。不(bu)過(guo)，諸(zhu)如室內光伏(fu)陣(zhen)列或(huo)壓電(dian)換能(neng)(neng)器等斷(duan)續性能(neng)(neng)量收集電(dian)源提供的(de)是功(gong)率突發(fa)。要用這類能(neng)(neng)源給(gei)電(dian)池充電(dian)，一(yi)個(ge)靜態工作電(dian)流低于(yu) 1uA 的(de)獨特 IC 是必需(xu)(xu)的(de)。

　　鋰(li)離子 / 聚合物化學組成(cheng)的電(dian)(dian)池(chi)(chi)提供便(bian)攜式電(dian)(dian)子設備(bei)必需的高(gao)性能(neng)(neng)(neng)，但是這類電(dian)(dian)池(chi)(chi)必須小心使用。例如(ru)，如(ru)果用比建議浮置電(dian)(dian)壓(ya)(ya)高(gao) 100mV 的電(dian)(dian)壓(ya)(ya)充(chong)電(dian)(dian)，鋰(li)離子 / 聚合物電(dian)(dian)池(chi)(chi)可(ke)能(neng)(neng)(neng)變得不(bu)穩定。此外(wai)，高(gao)壓(ya)(ya)和(he)高(gao)溫同時(shi)(shi)存在(zai)會(hui)對電(dian)(dian)池(chi)(chi)壽命產(chan)生有(you)害影響，而且在(zai)極端情況下，可(ke)能(neng)(neng)(neng)導致電(dian)(dian)池(chi)(chi)自毀。就(jiu)幣形(xing)電(dian)(dian)池(chi)(chi)和(he)薄膜電(dian)(dian)池(chi)(chi)而言，除了高(gao)溫和(he)高(gao)壓(ya)(ya)同時(shi)(shi)存在(zai)可(ke)能(neng)(neng)(neng)產(chan)生有(you)害影響，還(huan)有(you)容(rong)量問題，因為它們的外(wai)形(xing)尺寸很(hen)小。

　　并聯架構的基(ji)本要素和好處

　　并(bing)聯基(ji)準(zhun)是電流饋送型、兩(liang)端子電路(lu)，在(zai)達到目標電壓之前不(bu)吸取電流。并(bing)聯基(ji)準(zhun)用起(qi)來(lai)像(xiang)一個齊(qi)納(na)二(er)極管(guan)，而且在(zai)電路(lu)原理圖上常常顯(xian)示為一個齊(qi)納(na)二(er)極管(guan)。不(bu)過，大多數并(bing)聯基(ji)準(zhun)實際上都是基(ji)于帶隙基(ji)準(zhun)電壓的(de)。

　　一個并(bing)聯基準僅需要單個外部電阻器(qi)來調(diao)節(jie)輸出電壓，從而極其(qi)容易使用(yong)。沒有最高(gao)輸入電壓限制，最低輸入電壓由(you)基準電壓值設定，因為(wei)需要一些空間以正常運行。

　　此外，并聯(lian)基(ji)準在(zai)寬電流范圍內有良好(hao)的穩定性。很多并聯(lian)基(ji)準在(zai)有大(da)型(xing)(xing)或小(xiao)型(xing)(xing)容性負載(zai)時都(dou)是穩定的。

　　滿足前述電池充電器 IC 設計限制的(de)任何解決方案都必須兼有如下特(te)(te)(te)性：并(bing)聯穩壓器的(de)特(te)(te)(te)性;能用低(di)功率連續(xu)或(huo)斷續(xu)性電(dian)(dian)(dian)源充(chong)電(dian)(dian)(dian)的(de)電(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian) IC 的(de)特(te)(te)(te)性。這(zhe)樣(yang)的(de)器件還需要保護鋰離子(zi)/聚合(he)物電(dian)(dian)(dian)池(chi)(chi)、幣形電(dian)(dian)(dian)池(chi)(chi)、薄膜(mo)電(dian)(dian)(dian)池(chi)(chi)或(huo)電(dian)(dian)(dian)池(chi)(chi)組(zu)的(de)安全，并(bing)使電(dian)(dian)(dian)池(chi)(chi)或(huo)電(dian)(dian)(dian)池(chi)(chi)組(zu)達到最高性能。

　　凌力爾特開發了業界第一款(kuan)并(bing)聯(lian)(lian)架構電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器 LTC4070 和(he) LTC4071，以(yi)(yi)滿足這類應(ying)用的(de)(de)(de)需求。LTC4070 是一款(kuan)易用、纖巧(qiao)的(de)(de)(de)并(bing)聯(lian)(lian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器系統 IC，適用于(yu)鋰(li)離子 / 聚(ju)合物電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)、幣形(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)或薄膜(mo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)。該 IC 的(de)(de)(de)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流為(wei) 450nA，可(ke)(ke)保護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)，并(bing)可(ke)(ke)用以(yi)(yi)前(qian)不(bu)能(neng)(neng)(neng)(neng)使用的(de)(de)(de)非常小電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)(de)斷續性或連續性充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源給(gei)這些電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。增(zeng)加一個外(wai)部(bu) PMOS 并(bing)聯(lian)(lian)器件，LTC4070 的(de)(de)(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流就可(ke)(ke)以(yi)(yi)從 50mA 提(ti)高(gao)到 500mA。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)溫度升高(gao)時，內部(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)熱量查驗(yan)器降低(di)浮置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，以(yi)(yi)保護鋰(li)離子 / 聚(ju)合物電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)安(an)全。通過串聯(lian)(lian)配(pei)置幾(ji)個 LTC4070，可(ke)(ke)以(yi)(yi)給(gei)由多(duo)節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組成(cheng)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并(bing)實現各節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)容量平衡(heng)。LTC4070 采用扁平 (0.75mm) 8 引(yin)線 2mm x 3mm DFN 封裝，僅用單個外(wai)部(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻器 (要(yao)求與(yu)輸(shu)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)串聯(lian)(lian)) 就能(neng)(neng)(neng)(neng)組成(cheng)一個完(wan)整和(he)超(chao)緊湊的(de)(de)(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器解決方(fang)案。該器件的(de)(de)(de)功能(neng)(neng)(neng)(neng)集(ji)(ji)使其非常適用于(yu)連續性和(he)斷續性低(di)功率充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源應(ying)用，包(bao)括鋰(li)離子 / 聚(ju)合物電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)備(bei)份、薄膜(mo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)、幣形(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)、存儲器備(bei)份、太陽能(neng)(neng)(neng)(neng)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)系統、嵌入式汽車和(he)能(neng)(neng)(neng)(neng)量收集(ji)(ji)。

　　LTC4070提供引腳可(ke)選的 4.0V、4.1V 和 4.2V 設置(zhi)，其(qi)準確度(du)為(wei) 1% 的電(dian)池(chi)浮置(zhi)電(dian)壓允許用戶(hu)在電(dian)池(chi)能(neng)量(liang)密(mi)度(du)和壽命之間(jian)進行取舍(she)。獨立的低電(dian)池(chi)電(dian)量(liang)和高電(dian)池(chi)電(dian)量(liang)監察狀態輸(shu)出指示放(fang)(fang)電(dian)或完全(quan)充電(dian)的電(dian)池(chi)。再加上一(yi)個與負載(zai)(zai)串(chuan)聯的外部 P-FET，該低電(dian)池(chi)電(dian)量(liang)狀態輸(shu)出可(ke)實(shi)現鎖斷功(gong)能(neng)，該功(gong)能(neng)自動斷接(jie)系統(tong)負載(zai)(zai)和電(dian)池(chi)，以(yi)防止電(dian)池(chi)深度(du)放(fang)(fang)電(dian)。

　　除了緊湊的 2mm x 3mm 8 引(yin)線(xian) DFN 封(feng)裝，LTC4070 還采用 8 引(yin)線(xian) MSOP。這些器件規定在(zai) -40?C 至 125?C 的溫度范圍內工(gong)作。

　　通過(guo)防止電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓超過(guo)設定水平，LTC4070 提供了(le)一個簡單、可靠、高性能(neng)的電(dian)(dian)(dian)(dian)池(chi)(chi)保護和(he)充電(dian)(dian)(dian)(dian)解(jie)決方案。其并聯架(jia)構在輸入電(dian)(dian)(dian)(dian)源和(he)電(dian)(dian)(dian)(dian)池(chi)(chi)之(zhi)間(jian)僅需要一個電(dian)(dian)(dian)(dian)阻器，就可應(ying)(ying)對(dui)多種電(dian)(dian)(dian)(dian)池(chi)(chi)應(ying)(ying)用。當(dang)輸入電(dian)(dian)(dian)(dian)源去掉(diao)，且電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓低于高的電(dian)(dian)(dian)(dian)池(chi)(chi)輸出(chu)門限時，LTC4070 僅從電(dian)(dian)(dian)(dian)池(chi)(chi)吸取 450nA 電(dian)(dian)(dian)(dian)流。

　　當電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓低于(yu)設定的浮(fu)置電(dian)(dian)(dian)壓時，充電(dian)(dian)(dian)速率由輸入電(dian)(dian)(dian)壓、電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓和(he)輸入電(dian)(dian)(dian)阻(zu)器(qi)決定：

　　ICHG = (VIN ? VBAT) / RIN

　　當電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)接近浮置電(dian)(dian)(dian)(dian)壓(ya)時(shi)，LTC4070 從(cong)電(dian)(dian)(dian)(dian)池(chi)分(fen)走一(yi)部分(fen)電(dian)(dian)(dian)(dian)流(liu)(liu)，從(cong)而降(jiang)低了充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)。在整個溫度范圍內變化浮置電(dian)(dian)(dian)(dian)壓(ya)的(de)準確度為 ±1% 時(shi)，LTC4070 可以分(fen)走高(gao)達 50mA 的(de)電(dian)(dian)(dian)(dian)流(liu)(liu)。分(fen)流(liu)(liu)限制了最大充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)，不過通過增加一(yi)個外(wai)部 P 溝(gou)道 MOSFET，50mA 的(de)內部分(fen)流(liu)(liu)能(neng)力還可以提高(gao)，參見圖 1。

　　在(zai)內部，LTC4070 采用了一個(ge)由放(fang)大器(qi) EA (參見圖(tu) 2) 驅動的(de) P 溝道 MOSFET。VCC 和 GND 之(zhi)間(jian)的(de)電(dian)壓(ya)達到 VF (即并聯(lian)電(dian)壓(ya)) 之(zhi)前，流(liu)經該(gai)器(qi)件(jian)的(de)電(dian)流(liu)為(wei)零(ling)。VF 可(ke)以(yi)由 ADJ 和 NTC 改(gai)變，但始(shi)終(zhong)在(zai) 3.8V 到 4.2V 之(zhi)間(jian)。如果 VCC 電(dian)壓(ya)低于(yu)這(zhe)個(ge)值(zhi)，那么(me) PFET 中的(de)電(dian)流(liu)為(wei)零(ling)。如果 VCC電(dian)壓(ya)試圖(tu)上(shang)(shang)升(sheng)到超過(guo) VF，那么(me)電(dian)流(liu)將流(liu)過(guo)該(gai)器(qi)件(jian)，以(yi)防止(zhi)電(dian)壓(ya)上(shang)(shang)升(sheng)，這(zhe)就(jiu)是分(fen)流(liu)。

　　工(gong)作電流是(shi)給該芯片(pian)中其余所有電路供(gong)電所需的(de)電流。如果不存在外部(bu)電源，那么這就(jiu)是(shi)從電池吸取的(de)電流。

　　當(dang)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓(ya)低(di)時，更多的(de)電(dian)(dian)(dian)壓(ya)加(jia)在輸(shu)入(ru)(ru)電(dian)(dian)(dian)阻器(qi)兩端，因此進(jin)入(ru)(ru)電(dian)(dian)(dian)池(chi)的(de)電(dian)(dian)(dian)流(liu) (即充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)) 略大(da)于電(dian)(dian)(dian)池(chi)完全充(chong)電(dian)(dian)(dian)時的(de)電(dian)(dian)(dian)流(liu)。當(dang)電(dian)(dian)(dian)池(chi)充(chong)滿電(dian)(dian)(dian)時，將(jiang)沒有(you)電(dian)(dian)(dian)流(liu)進(jin)入(ru)(ru)電(dian)(dian)(dian)池(chi)，所有(you)的(de)輸(shu)入(ru)(ru)電(dian)(dian)(dian)流(liu)都將(jiang)進(jin)入(ru)(ru)分流(liu)器(qi)。

　　工作(zuo)電(dian)(dian)流很(hen)重要，因為它給“實(shi)際”輸入電(dian)(dian)源(yuan)的(de)(de)電(dian)(dian)流能(neng)力(li)設定(ding)了一(yi)個低限(xian)制。顯然(ran)，一(yi)個僅有(you) 100nA驅(qu)動能(neng)力(li)的(de)(de)輸入電(dian)(dian)源(yuan)不可能(neng)給采用(yong) LTC4070 的(de)(de)電(dian)(dian)池充(chong)電(dian)(dian)。不過，如果(guo)有(you) 1uA 的(de)(de)驅(qu)動能(neng)力(li)，就能(neng)剩下少量電(dian)(dian)流去充(chong)電(dian)(dian)。如果(guo)能(neng)得到(dao) 10uA 的(de)(de)驅(qu)動能(neng)力(li)，那么該電(dian)(dian)流 90% 以上都可用(yong)于充(chong)電(dian)(dian)。

　　NTC 電(dian)池查驗電(dian)路保(bao)護(hu)電(dian)池

　　LTC4070 用一(yi)個通過熱(re)量耦合到電(dian)(dian)池的負溫(wen)(wen)度(du)系數(shu)熱(re)敏電(dian)(dian)阻測量電(dian)(dian)池溫(wen)(wen)度(du)。NTC 熱(re)敏電(dian)(dian)阻的溫(wen)(wen)度(du)特(te)性(xing)在電(dian)(dian)阻-溫(wen)(wen)度(du)轉換表(biao)中規(gui)定。在溫(wen)(wen)度(du)高(gao)于 40°C 以后，每上升(sheng) 10°C，內部 NTC 電(dian)(dian)路就降低一(yi)次浮(fu)置電(dian)(dian)壓，以防止電(dian)(dian)池過熱(re) (參見圖 3 以了解詳細信息)。

　　LTC4070 采用一個(ge)電(dian)阻值之(zhi)比來(lai)測(ce)量(liang)電(dian)池(chi)溫(wen)度(du)。LTC4070 在 NTCBIAS 與 GND 引腳(jiao)之(zhi)間布設了(le)一個(ge)具 4 個(ge)抽頭的內(nei)部固定電(dian)阻分壓(ya)器。定期地將(jiang)這些抽頭上的電(dian)壓(ya)與 NTC 引腳(jiao)上的電(dian)壓(ya)進行(xing)比較，以測(ce)量(liang)電(dian)池(chi)溫(wen)度(du)。為了(le)節省功率，通過以大約(yue)每 1.5s 一次的頻度(du)把 NTCBIAS 引腳(jiao)偏置至 VCC 來(lai)定期測(ce)量(liang)電(dian)池(chi)溫(wen)度(du)。

    LTC4070 具有一個與 ADJ 引腳相(xiang)連(lian)的(de)內置(zhi)(zhi)三態(tai)解(jie)碼(ma)器(qi)，用以提供 3 種可編(bian)程浮(fu)置(zhi)(zhi)電(dian)(dian)(dian)壓(ya)：4.0V、4.1V、或(huo) 4.2V。當 ADJ 引腳連(lian)接(jie)至 GND、浮(fu)置(zhi)(zhi)或(huo)連(lian)接(jie)至 VCC 時，浮(fu)置(zhi)(zhi)電(dian)(dian)(dian)壓(ya)將被(bei)(bei)分別設置(zhi)(zhi)為(wei) 4.0V、4.1V 或(huo) 4.2V。大約每 1.5s 對 ADJ 引腳的(de)狀態(tai)進行(xing)一次采(cai)樣(yang)。當 ADJ 引腳被(bei)(bei)采(cai)樣(yang)時，LTC4070 在其(qi)上施(shi)加一個相(xiang)對較低(di)(di)的(de)阻(zu)(zu)抗電(dian)(dian)(dian)壓(ya)。這(zhe)種做法可以防止低(di)(di)水平的(de)電(dian)(dian)(dian)路板漏電(dian)(dian)(dian)流破壞(huai)設定的(de)浮(fu)置(zhi)(zhi)電(dian)(dian)(dian)壓(ya)。免除電(dian)(dian)(dian)阻(zu)(zu)器(qi)不僅縮減了(le)解(jie)決(jue)方案(an)的(de)外(wai)形尺寸，而且還由于無需使用大阻(zu)(zu)值的(de)電(dian)(dian)(dian)阻(zu)(zu)器(qi)而降低(di)(di)了(le)靜態(tai)電(dian)(dian)(dian)流。

　　另外(wai)，該器(qi)件(jian)還具(ju)有狀態輸(shu)(shu)出(chu)(chu)(chu)及發送指(zhi)示信號(hao)的能力。高電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)量監視器(qi)輸(shu)(shu)出(chu)(chu)(chu) (HBO) 是一個(ge)高態有效 CMOS 輸(shu)(shu)出(chu)(chu)(chu)，當電(dian)(dian)(dian)(dian)(dian)池(chi)充滿電(dian)(dian)(dian)(dian)(dian)且電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)通過分(fen)路(lu)離開 BAT 時(shi)，該輸(shu)(shu)出(chu)(chu)(chu)將(jiang)發出(chu)(chu)(chu)指(zhi)示信號(hao)。低電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)量監視器(qi)輸(shu)(shu)出(chu)(chu)(chu) (LBO) 也是一個(ge)高態有效 CMOS 輸(shu)(shu)出(chu)(chu)(chu)，當電(dian)(dian)(dian)(dian)(dian)池(chi)放電(dian)(dian)(dian)(dian)(dian)至(zhi) 3.2V 以下時(shi)，此輸(shu)(shu)出(chu)(chu)(chu)將(jiang)發出(chu)(chu)(chu)對應(ying)的指(zhi)示信號(hao)。最(zui)后，外(wai)部(bu)驅動器(qi)輸(shu)(shu)出(chu)(chu)(chu)引腳 DRV 可(ke)連接至(zhi)外(wai)部(bu) P-FET 的柵極以增加分(fen)路(lu)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，從(cong)而滿足那些(xie)需要 50mA 以上充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu) (最(zui)大 500mA) 的應(ying)用。

　　LTC4071 集成電(dian)池(chi)組保(bao)護功(gong)能

　　LTC4071 也是(shi)一(yi)(yi)個并聯電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器系統(tong)，而(er)且還(huan)是(shi)首款具有集成(cheng)型(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組保(bao)護功(gong)(gong)能(neng) (包(bao)括(kuo)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接(jie)(jie)) 的(de)(de)(de)(de)器件。相(xiang)比于(yu) LTC4070，LTC4071 的(de)(de)(de)(de)不(bu)同(tong)之(zhi)處包(bao)括(kuo)：其擁有集成(cheng)型(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組保(bao)護功(gong)(gong)能(neng) (低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接(jie)(jie)) 、但(dan)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)能(neng)力較(jiao)低(di) (50mA)、靜態電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)較(jiao)高 (550nA) 、且不(bu)具備 LBO。對于(yu)避免低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)由于(yu)自放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)而(er)受損而(er)言，低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接(jie)(jie)是(shi)一(yi)(yi)種必需的(de)(de)(de)(de)關鍵(jian)性功(gong)(gong)能(neng)。雖然 LTC4070 能(neng)夠利(li)用 LBO 和一(yi)(yi)個外(wai)(wai)部 P-FET 來(lai)實現低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接(jie)(jie)功(gong)(gong)能(neng)，但(dan)該(gai) IC 仍將繼續從電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)消耗全(quan)部 IQ (約 0.5μA)。即使是(shi)如此之(zhi)小的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)漏電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)也會在一(yi)(yi)夜之(zhi)間(jian)導致低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)損壞(huai)。相(xiang)反，LTC4071 集成(cheng)了(le)一(yi)(yi)個徹底的(de)(de)(de)(de)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)斷(duan)接(jie)(jie)功(gong)(gong)能(neng)，當(dang)斷(duan)接(jie)(jie)時，從電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)吸取的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)接(jie)(jie)近零 (在室溫時 <1nA，在 125°C 時 < 25nA)。為了(le)在 LTC4071 中提(ti)供這(zhe)(zhe)一(yi)(yi)功(gong)(gong)能(neng)，相(xiang)應于(yu) LTC4070 的(de)(de)(de)(de) LBO 和 DRV 引腳被去(qu)掉(diao)了(le)。參見圖 4 以(yi)了(le)解詳細信息。這(zhe)(zhe)使 LTC4071 的(de)(de)(de)(de)最大分流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)固定為 50mA (LTC4070 是(shi) 50mA，但(dan)采(cai)用一(yi)(yi)個外(wai)(wai)部 FET，就(jiu)能(neng)達到 500mA)，而(er)且將該(gai) IC 的(de)(de)(de)(de)靜態電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)提(ti)高到了(le) 550nA (LTC4070 的(de)(de)(de)(de)靜態電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)為 450nA)。下表 1 總結(jie)了(le)這(zhe)(zhe)兩(liang)個相(xiang)互關聯的(de)(de)(de)(de) IC 之(zhi)間(jian)的(de)(de)(de)(de)差別。

　　結論

　　并(bing)(bing)聯(lian)基準(zhun)有很(hen)多應(ying)(ying)用(yong)，而且(qie)視其功能的不(bu)同而不(bu)同，并(bing)(bing)聯(lian)基準(zhun)甚至可(ke)以用(yong)來給電(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)。不(bu)過，這種類型的應(ying)(ying)用(yong)有很(hen)多缺點(dian)，包括(kuo)大靜態電(dian)(dian)(dian)流和(he)(he)缺乏(fa)電(dian)(dian)(dian)池(chi)(chi)保護(hu)功能。現在，有了合適的 DC-DC 轉換器或電(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)器，因此可(ke)以對(dui)低功率能量(liang)收(shou)集應(ying)(ying)用(yong)進行查驗了。凌力爾(er)特公司開發了 LTC4070 和(he)(he) LTC4071 并(bing)(bing)聯(lian)充(chong)(chong)電(dian)(dian)(dian)器系統，這兩(liang)款器件適用(yong)于鋰離子 / 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)和(he)(he)電(dian)(dian)(dian)池(chi)(chi)組，可(ke)為(wei)具有低功率電(dian)(dian)(dian)源的領(ling)先應(ying)(ying)用(yong)提(ti)供(gong)一種簡(jian)單、有效(xiao)的電(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)和(he)(he)電(dian)(dian)(dian)池(chi)(chi)組保護(hu)解決方案(an)。