在市場上，能(neng)量(liang)收(shou)集 IC 剛剛進(jin)入最初(chu)采用階段。能(neng)量(liang)收(shou)集 IC 可將(jiang)適合的換能(neng)器輸出轉換成電流，用于電池充(chong)電器設備(bei)。盡管能(neng)量(liang)收(shou)集自 2000 年初(chu)就已(yi)經出現(xian)了(le)，但是最近的技術發展才(cai)將(jiang)能(neng)量(liang)收(shou)集推進(jin)到可商用的程度。在能(neng)量(liang)收(shou)集應用領域有很(hen)多機會，包(bao)括(kuo)：

　　? 在更換(huan)電(dian)(dian)池不方便、不現(xian)實或危險的情況下，取代(dai)電(dian)(dian)池供(gong)電(dian)(dian)系(xi)統或給電(dian)(dian)池供(gong)電(dian)(dian)系(xi)統再充電(dian)(dian)

　　? 無(wu)需導線來供電(dian)或傳送數據(ju)

　　? 用智能無線(xian)傳(chuan)感(gan)器網絡監視(shi)和優化復雜的工業過程、安裝在偏遠現場的設備、以及大樓的加熱(re)和冷卻系統

　　? 從工業過程、太陽(yang)能電池板(ban)、內燃(ran)機(ji)等收集否(fou)則會浪費掉的熱量(liang)

　　? 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，有很多含有固有的斷續(xu)或低功率(lv)電源。而且，有很多應(ying)用(yong)將需(xu)要給電池充電，以提供一個(ge)備(bei)份電源。

　　并聯電(dian)壓(ya)基(ji)準(zhun)簡(jian)單易用，已經出現很多年了，有大量產品(pin)。不(bu)過，這類基(ji)準(zhun)不(bu)能有效地給電(dian)池(chi)充電(dian)。要(yao)配置一個(ge)并聯電(dian)壓(ya)基(ji)準(zhun)以給電(dian)池(chi)有效充電(dian)是極端復(fu)雜(za)的(de)。此外(wai)，用一個(ge)小電(dian)流(liu)電(dian)源或一個(ge)斷續性(xing)能量收集電(dian)源準(zhun)確和安全地給鋰(li)離(li)子 / 聚合物、幣形(xing)電(dian)池(chi)或薄膜電(dian)池(chi)充電(dian)，一直是難(nan)以實現的(de)。

　　從電(dian)(dian)(dian)池方面來看，盡管技術(shu)已經改進了，但是(shi)便攜式電(dian)(dian)(dian)子設備的(de)電(dian)(dian)(dian)池或電(dian)(dian)(dian)池組仍然需要保護(hu)(hu)和查驗，以(yi)保持(chi)電(dian)(dian)(dian)池在最佳狀態運行。鋰離子 / 聚(ju)合物電(dian)(dian)(dian)池技術(shu)已經成熟，是(shi)很(hen)(hen)多電(dian)(dian)(dian)子設備流行的(de)電(dian)(dian)(dian)源選擇，因為這類電(dian)(dian)(dian)池能(neng)量密度高(gao)、自放(fang)電(dian)(dian)(dian)很(hen)(hen)少、需要很(hen)(hen)少的(de)維護(hu)(hu)、電(dian)(dian)(dian)壓范圍很(hen)(hen)寬并具有(you)(you)(you)(you)其他一(yi)(yi)些特色(se)。幣形電(dian)(dian)(dian)池能(neng)量密度高(gao)、放(fang)電(dian)(dian)(dian)特性(xing)穩定、重量輕且外形尺寸小。薄膜電(dian)(dian)(dian)池是(shi)一(yi)(yi)種新(xin)出(chu)現的(de)技術(shu)，優勢是(shi)允(yun)許非常多的(de)充電(dian)(dian)(dian)周期次數(shu)，并具有(you)(you)(you)(you)物理靈活性(xing)，即視最終應用的(de)不同(tong)(tong)而不同(tong)(tong)，薄膜電(dian)(dian)(dian)池可以(yi)做成幾乎任何形狀。不過，如果不能(neng)正確充電(dian)(dian)(dian)和查驗，那么所(suo)有(you)(you)(you)(you)這些類型的(de)電(dian)(dian)(dian)池都可能(neng)受到一(yi)(yi)些有(you)(you)(you)(you)害影(ying)響。

　　低功(gong)耗充電(dian)器的設計挑戰

　　可調并聯(lian)基(ji)準(zhun)可被(bei)設定以提供(gong)恰當的電(dian)(dian)(dian)池(chi)浮(fu)置電(dian)(dian)(dian)壓(ya)，但是這類基(ji)準(zhun)缺乏電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)器的 NTC 功(gong)能(neng)。更(geng)重(zhong)要的是，所需的工作電(dian)(dian)(dian)流太高了，以至于(yu)用(yong)低(di)功(gong)率電(dian)(dian)(dian)源或(huo)斷(duan)續性電(dian)(dian)(dian)源給電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)是不(bu)現實(shi)(shi)的。或(huo)者，可以用(yong)一(yi)個齊(qi)納二極管、一(yi)些電(dian)(dian)(dian)阻器、一(yi)個 NPN 晶體(ti)管和一(yi)些比(bi)較器構(gou)成一(yi)個分立式并聯(lian)基(ji)準(zhun)，以提供(gong) NTC 功(gong)能(neng)。不(bu)過(guo)，這樣的并聯(lian)基(ji)準(zhun)仍然受到前(qian)述限制(zhi)。此外，分立式并聯(lian)基(ji)準(zhun)實(shi)(shi)現起(qi)來比(bi)較復雜，相比(bi)之(zhi)下，會占用(yong)更(geng)多寶貴的 PCB 面(mian)積(ji)。

　　典型(xing)的(de)(de)電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)器(qi)(qi) IC 需要恒(heng)定 DC 輸(shu)入(ru)電(dian)(dian)(dian)壓，而且(qie)不能處理能量突(tu)發(fa)(fa)。不過，諸如(ru)室內光伏陣列(lie)或壓電(dian)(dian)(dian)換能器(qi)(qi)等斷續(xu)性能量收集電(dian)(dian)(dian)源(yuan)提供的(de)(de)是功(gong)率突(tu)發(fa)(fa)。要用這類(lei)能源(yuan)給電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)，一個(ge)靜態工作(zuo)電(dian)(dian)(dian)流低于 1uA 的(de)(de)獨特 IC 是必需的(de)(de)。

　　鋰離子 / 聚(ju)合物化(hua)學組(zu)成(cheng)的(de)(de)(de)電(dian)(dian)(dian)池(chi)(chi)(chi)提(ti)供便(bian)攜式電(dian)(dian)(dian)子設備(bei)必需的(de)(de)(de)高(gao)(gao)(gao)性能(neng)(neng)，但是這類電(dian)(dian)(dian)池(chi)(chi)(chi)必須小心使用。例如(ru)，如(ru)果用比建議浮置電(dian)(dian)(dian)壓(ya)(ya)高(gao)(gao)(gao) 100mV 的(de)(de)(de)電(dian)(dian)(dian)壓(ya)(ya)充電(dian)(dian)(dian)，鋰離子 / 聚(ju)合物電(dian)(dian)(dian)池(chi)(chi)(chi)可(ke)能(neng)(neng)變得不穩定。此外，高(gao)(gao)(gao)壓(ya)(ya)和高(gao)(gao)(gao)溫(wen)同(tong)時(shi)存在會對電(dian)(dian)(dian)池(chi)(chi)(chi)壽命產(chan)生(sheng)有(you)害影響，而(er)且(qie)在極端情況下，可(ke)能(neng)(neng)導致電(dian)(dian)(dian)池(chi)(chi)(chi)自毀。就幣形電(dian)(dian)(dian)池(chi)(chi)(chi)和薄膜電(dian)(dian)(dian)池(chi)(chi)(chi)而(er)言，除(chu)了高(gao)(gao)(gao)溫(wen)和高(gao)(gao)(gao)壓(ya)(ya)同(tong)時(shi)存在可(ke)能(neng)(neng)產(chan)生(sheng)有(you)害影響，還有(you)容量問(wen)題，因為它們的(de)(de)(de)外形尺寸(cun)很小。

　　并聯架構的(de)基本(ben)要素和好處

　　并(bing)聯(lian)基(ji)準(zhun)(zhun)是電流饋送(song)型(xing)、兩端子電路(lu)，在(zai)達(da)到目標電壓(ya)之(zhi)前不吸取電流。并(bing)聯(lian)基(ji)準(zhun)(zhun)用起(qi)來(lai)像一(yi)個齊(qi)納二極管，而(er)且(qie)在(zai)電路(lu)原理圖上常常顯示(shi)為一(yi)個齊(qi)納二極管。不過，大多數并(bing)聯(lian)基(ji)準(zhun)(zhun)實際上都是基(ji)于帶隙基(ji)準(zhun)(zhun)電壓(ya)的。

　　一個并聯基準(zhun)僅需要單個外(wai)部(bu)電阻器來調節輸出電壓(ya)，從而極(ji)其容易使用。沒有最(zui)高輸入電壓(ya)限制(zhi)，最(zui)低輸入電壓(ya)由基準(zhun)電壓(ya)值設定，因為(wei)需要一些空間以(yi)正常運行。

　　此(ci)外(wai)，并聯(lian)基(ji)準在寬電流范圍(wei)內有良(liang)好的穩定性(xing)。很(hen)多并聯(lian)基(ji)準在有大型或小型容性(xing)負載時都(dou)是穩定的。

　　滿足前述電池充電器 IC 設計限(xian)制的(de)任何(he)解決(jue)方(fang)案都必須兼有如下(xia)特性(xing)：并(bing)聯穩壓器的(de)特性(xing);能用低(di)功率連續或(huo)斷續性(xing)電(dian)(dian)源充(chong)電(dian)(dian)的(de)電(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)電(dian)(dian) IC 的(de)特性(xing)。這樣(yang)的(de)器件還需要(yao)保護鋰離子/聚合物電(dian)(dian)池(chi)(chi)(chi)(chi)、幣形電(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)組的(de)安(an)全，并(bing)使電(dian)(dian)池(chi)(chi)(chi)(chi)或(huo)電(dian)(dian)池(chi)(chi)(chi)(chi)組達到最高性(xing)能。

　　凌力(li)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)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi) LTC4070 和(he) LTC4071，以滿足這類應用的(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)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)系統(tong) IC，適用于(yu)鋰離子(zi) / 聚(ju)合物(wu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)、幣形(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)或(huo)薄膜電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)。該(gai) IC 的(de)(de)(de)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流為 450nA，可(ke)保(bao)護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)，并(bing)可(ke)用以前不(bu)能(neng)(neng)使用的(de)(de)(de)非常小電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)(de)斷續(xu)性(xing)或(huo)連續(xu)性(xing)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源給這些電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。增(zeng)加一個(ge)(ge)(ge)外部(bu) PMOS 并(bing)聯(lian)(lian)器(qi)件(jian)，LTC4070 的(de)(de)(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流就可(ke)以從 50mA 提(ti)高(gao)到 500mA。當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)溫(wen)度升高(gao)時，內部(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)熱量查驗(yan)器(qi)降(jiang)低浮置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓，以保(bao)護(hu)鋰離子(zi) / 聚(ju)合物(wu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)的(de)(de)(de)安全。通過(guo)串聯(lian)(lian)配置幾個(ge)(ge)(ge) LTC4070，可(ke)以給由多節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)組成(cheng)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)組充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，并(bing)實現各節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)的(de)(de)(de)容量平衡(heng)。LTC4070 采(cai)用扁平 (0.75mm) 8 引(yin)線 2mm x 3mm DFN 封裝，僅用單個(ge)(ge)(ge)外部(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻器(qi) (要求與輸入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓串聯(lian)(lian)) 就能(neng)(neng)組成(cheng)一個(ge)(ge)(ge)完(wan)整和(he)超(chao)緊(jin)湊的(de)(de)(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)解(jie)決方案。該(gai)器(qi)件(jian)的(de)(de)(de)功能(neng)(neng)集(ji)使其非常適用于(yu)連續(xu)性(xing)和(he)斷續(xu)性(xing)低功率(lv)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源應用，包(bao)括鋰離子(zi) / 聚(ju)合物(wu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)備份、薄膜電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)、幣形(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)(chi)、存儲器(qi)備份、太陽能(neng)(neng)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)系統(tong)、嵌(qian)入式汽(qi)車和(he)能(neng)(neng)量收集(ji)。

　　LTC4070提(ti)供引腳可(ke)選的(de) 4.0V、4.1V 和(he) 4.2V 設置(zhi)，其準(zhun)確度為 1% 的(de)電(dian)(dian)(dian)池(chi)(chi)(chi)浮置(zhi)電(dian)(dian)(dian)壓允許用戶(hu)在電(dian)(dian)(dian)池(chi)(chi)(chi)能量(liang)(liang)密度和(he)壽命之間進行取(qu)舍(she)。獨立的(de)低(di)電(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)量(liang)(liang)和(he)高電(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)量(liang)(liang)監(jian)察(cha)狀(zhuang)態輸出(chu)指(zhi)示放(fang)(fang)電(dian)(dian)(dian)或完全充電(dian)(dian)(dian)的(de)電(dian)(dian)(dian)池(chi)(chi)(chi)。再加上(shang)一(yi)個與負載串聯的(de)外部 P-FET，該低(di)電(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)量(liang)(liang)狀(zhuang)態輸出(chu)可(ke)實現鎖斷(duan)功(gong)能，該功(gong)能自動斷(duan)接系(xi)統負載和(he)電(dian)(dian)(dian)池(chi)(chi)(chi)，以防止電(dian)(dian)(dian)池(chi)(chi)(chi)深度放(fang)(fang)電(dian)(dian)(dian)。

　　除(chu)了緊湊的(de) 2mm x 3mm 8 引(yin)線(xian)(xian) DFN 封裝，LTC4070 還采用 8 引(yin)線(xian)(xian) MSOP。這些器件規定在 -40?C 至 125?C 的(de)溫度范圍(wei)內(nei)工作。

　　通(tong)過防止(zhi)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓超過設定水平，LTC4070 提(ti)供了一個簡(jian)單、可靠(kao)、高性能的電(dian)(dian)(dian)池(chi)保護和(he)(he)充電(dian)(dian)(dian)解決方案(an)。其并聯架構(gou)在(zai)輸(shu)入電(dian)(dian)(dian)源(yuan)和(he)(he)電(dian)(dian)(dian)池(chi)之間僅需要一個電(dian)(dian)(dian)阻器，就可應對多種(zhong)電(dian)(dian)(dian)池(chi)應用。當輸(shu)入電(dian)(dian)(dian)源(yuan)去掉(diao)，且(qie)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓低于高的電(dian)(dian)(dian)池(chi)輸(shu)出門限時(shi)，LTC4070 僅從電(dian)(dian)(dian)池(chi)吸取 450nA 電(dian)(dian)(dian)流(liu)。

　　當電(dian)池(chi)電(dian)壓(ya)低(di)于設定的浮置(zhi)電(dian)壓(ya)時，充(chong)電(dian)速率由輸入(ru)(ru)電(dian)壓(ya)、電(dian)池(chi)電(dian)壓(ya)和輸入(ru)(ru)電(dian)阻器決(jue)定：

　　ICHG = (VIN ? VBAT) / RIN

　　當電(dian)(dian)池(chi)電(dian)(dian)壓(ya)(ya)接近浮置(zhi)電(dian)(dian)壓(ya)(ya)時，LTC4070 從電(dian)(dian)池(chi)分走一(yi)(yi)部分電(dian)(dian)流(liu)，從而降低了(le)充電(dian)(dian)電(dian)(dian)流(liu)。在(zai)整個溫度范圍內(nei)變化浮置(zhi)電(dian)(dian)壓(ya)(ya)的(de)準確度為 ±1% 時，LTC4070 可以分走高達 50mA 的(de)電(dian)(dian)流(liu)。分流(liu)限制了(le)最大充電(dian)(dian)電(dian)(dian)流(liu)，不過通過增(zeng)加一(yi)(yi)個外(wai)部 P 溝(gou)道(dao) MOSFET，50mA 的(de)內(nei)部分流(liu)能力還(huan)可以提(ti)高，參見圖 1。

　　在內部，LTC4070 采用(yong)了(le)一(yi)個(ge)由放大器(qi) EA (參見圖 2) 驅(qu)動的 P 溝(gou)道(dao) MOSFET。VCC 和 GND 之間的電(dian)壓(ya)達到(dao) VF (即(ji)并聯電(dian)壓(ya)) 之前，流(liu)(liu)經該器(qi)件(jian)的電(dian)流(liu)(liu)為(wei)(wei)零。VF 可以由 ADJ 和 NTC 改(gai)變，但(dan)始終(zhong)在 3.8V 到(dao) 4.2V 之間。如(ru)果 VCC 電(dian)壓(ya)低(di)于這個(ge)值(zhi)，那么 PFET 中(zhong)的電(dian)流(liu)(liu)為(wei)(wei)零。如(ru)果 VCC電(dian)壓(ya)試圖上(shang)(shang)升到(dao)超過 VF，那么電(dian)流(liu)(liu)將流(liu)(liu)過該器(qi)件(jian)，以防止電(dian)壓(ya)上(shang)(shang)升，這就是分流(liu)(liu)。

　　工作(zuo)電(dian)流(liu)是給(gei)該芯片中(zhong)其余所有電(dian)路供電(dian)所需的(de)電(dian)流(liu)。如果不存(cun)在(zai)外部電(dian)源，那么這就是從電(dian)池吸取的(de)電(dian)流(liu)。

　　當電(dian)池(chi)(chi)(chi)電(dian)壓(ya)低(di)時，更多的(de)電(dian)壓(ya)加在輸入(ru)(ru)電(dian)阻器兩端，因(yin)此進入(ru)(ru)電(dian)池(chi)(chi)(chi)的(de)電(dian)流 (即(ji)充電(dian)電(dian)流) 略大于電(dian)池(chi)(chi)(chi)完全充電(dian)時的(de)電(dian)流。當電(dian)池(chi)(chi)(chi)充滿電(dian)時，將(jiang)沒有電(dian)流進入(ru)(ru)電(dian)池(chi)(chi)(chi)，所有的(de)輸入(ru)(ru)電(dian)流都(dou)將(jiang)進入(ru)(ru)分流器。

　　工作(zuo)電(dian)流(liu)(liu)很(hen)重(zhong)要，因為它給“實際”輸入(ru)電(dian)源(yuan)(yuan)的(de)(de)電(dian)流(liu)(liu)能(neng)(neng)力(li)(li)設定了(le)一個(ge)低(di)限(xian)制。顯然，一個(ge)僅(jin)有 100nA驅動能(neng)(neng)力(li)(li)的(de)(de)輸入(ru)電(dian)源(yuan)(yuan)不(bu)可(ke)能(neng)(neng)給采用 LTC4070 的(de)(de)電(dian)池充電(dian)。不(bu)過(guo)，如(ru)果(guo)有 1uA 的(de)(de)驅動能(neng)(neng)力(li)(li)，就能(neng)(neng)剩下(xia)少(shao)量電(dian)流(liu)(liu)去充電(dian)。如(ru)果(guo)能(neng)(neng)得(de)到 10uA 的(de)(de)驅動能(neng)(neng)力(li)(li)，那么該電(dian)流(liu)(liu) 90% 以上都可(ke)用于充電(dian)。

　　NTC 電池查(cha)驗電路(lu)保護電池

　　LTC4070 用(yong)一(yi)個通(tong)過熱(re)量耦(ou)合到電(dian)(dian)池的負溫度系數(shu)熱(re)敏電(dian)(dian)阻(zu)(zu)測(ce)量電(dian)(dian)池溫度。NTC 熱(re)敏電(dian)(dian)阻(zu)(zu)的溫度特性在電(dian)(dian)阻(zu)(zu)-溫度轉換表中規定。在溫度高于 40°C 以后，每(mei)上升 10°C，內部 NTC 電(dian)(dian)路(lu)就降低一(yi)次(ci)浮置(zhi)電(dian)(dian)壓，以防(fang)止電(dian)(dian)池過熱(re) (參見圖 3 以了解(jie)詳細信息(xi))。

　　LTC4070 采用一個電(dian)(dian)阻值(zhi)之比(bi)來測(ce)(ce)量(liang)電(dian)(dian)池溫度(du)。LTC4070 在 NTCBIAS 與(yu) GND 引(yin)腳之間布設了(le)一個具 4 個抽(chou)頭(tou)的(de)內部(bu)固定電(dian)(dian)阻分壓(ya)器。定期地將這(zhe)些抽(chou)頭(tou)上(shang)的(de)電(dian)(dian)壓(ya)與(yu) NTC 引(yin)腳上(shang)的(de)電(dian)(dian)壓(ya)進行(xing)比(bi)較，以測(ce)(ce)量(liang)電(dian)(dian)池溫度(du)。為了(le)節省功率，通過以大約每 1.5s 一次的(de)頻度(du)把 NTCBIAS 引(yin)腳偏置(zhi)至 VCC 來定期測(ce)(ce)量(liang)電(dian)(dian)池溫度(du)。

    LTC4070 具(ju)有一(yi)(yi)個與 ADJ 引腳相(xiang)連的(de)內置三態解碼器，用以提供 3 種可編程浮(fu)置電(dian)壓(ya)：4.0V、4.1V、或 4.2V。當 ADJ 引腳連接至(zhi)(zhi) GND、浮(fu)置或連接至(zhi)(zhi) VCC 時(shi)，浮(fu)置電(dian)壓(ya)將被分別(bie)設(she)置為 4.0V、4.1V 或 4.2V。大約每 1.5s 對(dui) ADJ 引腳的(de)狀態進行一(yi)(yi)次(ci)采樣。當 ADJ 引腳被采樣時(shi)，LTC4070 在其上施加一(yi)(yi)個相(xiang)對(dui)較(jiao)低(di)的(de)阻抗電(dian)壓(ya)。這種做法可以防止低(di)水(shui)平的(de)電(dian)路板漏(lou)電(dian)流(liu)破壞(huai)設(she)定的(de)浮(fu)置電(dian)壓(ya)。免除電(dian)阻器不(bu)僅縮(suo)減了(le)解決方案(an)的(de)外(wai)形尺寸，而(er)且還由于無需使(shi)用大阻值的(de)電(dian)阻器而(er)降低(di)了(le)靜態電(dian)流(liu)。

　　另(ling)外，該器(qi)件(jian)還具有(you)狀態(tai)輸出(chu)(chu)(chu)及發送(song)指示信(xin)號(hao)的(de)(de)能力。高(gao)電(dian)池(chi)(chi)電(dian)量(liang)監(jian)視(shi)器(qi)輸出(chu)(chu)(chu) (HBO) 是一(yi)(yi)個高(gao)態(tai)有(you)效(xiao) CMOS 輸出(chu)(chu)(chu)，當(dang)電(dian)池(chi)(chi)充滿(man)電(dian)且(qie)電(dian)流通過分路離開 BAT 時，該輸出(chu)(chu)(chu)將(jiang)發出(chu)(chu)(chu)指示信(xin)號(hao)。低電(dian)池(chi)(chi)電(dian)量(liang)監(jian)視(shi)器(qi)輸出(chu)(chu)(chu) (LBO) 也是一(yi)(yi)個高(gao)態(tai)有(you)效(xiao) CMOS 輸出(chu)(chu)(chu)，當(dang)電(dian)池(chi)(chi)放電(dian)至 3.2V 以(yi)(yi)下(xia)時，此(ci)輸出(chu)(chu)(chu)將(jiang)發出(chu)(chu)(chu)對應(ying)的(de)(de)指示信(xin)號(hao)。最(zui)后，外部(bu)驅動器(qi)輸出(chu)(chu)(chu)引(yin)腳 DRV 可連接至外部(bu) P-FET 的(de)(de)柵極以(yi)(yi)增加(jia)分路電(dian)流，從而滿(man)足那些需(xu)要 50mA 以(yi)(yi)上充電(dian)電(dian)流 (最(zui)大 500mA) 的(de)(de)應(ying)用。

　　LTC4071 集(ji)成(cheng)電(dian)池(chi)組保護功能

　　LTC4071 也(ye)是(shi)(shi)一(yi)(yi)(yi)個(ge)并聯(lian)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)系統，而且還是(shi)(shi)首款具有(you)集成型電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)組保(bao)護功(gong)能(neng)(neng) (包括低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)斷接(jie)(jie)) 的(de)器(qi)件。相(xiang)比于 LTC4070，LTC4071 的(de)不同之處(chu)包括：其擁有(you)集成型電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)組保(bao)護功(gong)能(neng)(neng) (低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)斷接(jie)(jie)) 、但(dan)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)能(neng)(neng)力較低(di) (50mA)、靜(jing)態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)較高(gao) (550nA) 、且不具備 LBO。對(dui)于避免低(di)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)由于自放電(dian)(dian)(dian)(dian)(dian)(dian)而受損而言，低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)斷接(jie)(jie)是(shi)(shi)一(yi)(yi)(yi)種必需的(de)關鍵(jian)性功(gong)能(neng)(neng)。雖然 LTC4070 能(neng)(neng)夠利(li)用 LBO 和(he)一(yi)(yi)(yi)個(ge)外(wai)部(bu)(bu) P-FET 來實(shi)現低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)斷接(jie)(jie)功(gong)能(neng)(neng)，但(dan)該 IC 仍(reng)將繼續從電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)消耗全部(bu)(bu) IQ (約 0.5μA)。即使(shi)是(shi)(shi)如(ru)此(ci)之小(xiao)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)漏(lou)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)也(ye)會在(zai)一(yi)(yi)(yi)夜之間導致低(di)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)損壞。相(xiang)反，LTC4071 集成了(le)一(yi)(yi)(yi)個(ge)徹底(di)的(de)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)斷接(jie)(jie)功(gong)能(neng)(neng)，當(dang)斷接(jie)(jie)時，從電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)吸取的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)接(jie)(jie)近零 (在(zai)室溫(wen)時 <1nA，在(zai) 125°C 時 < 25nA)。為(wei)(wei)了(le)在(zai) LTC4071 中提供這(zhe)一(yi)(yi)(yi)功(gong)能(neng)(neng)，相(xiang)應于 LTC4070 的(de) LBO 和(he) DRV 引腳被(bei)去掉(diao)了(le)。參見圖(tu) 4 以了(le)解詳細(xi)信息。這(zhe)使(shi) LTC4071 的(de)最大分流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)固定為(wei)(wei) 50mA (LTC4070 是(shi)(shi) 50mA，但(dan)采(cai)用一(yi)(yi)(yi)個(ge)外(wai)部(bu)(bu) FET，就能(neng)(neng)達到 500mA)，而且將該 IC 的(de)靜(jing)態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)提高(gao)到了(le) 550nA (LTC4070 的(de)靜(jing)態(tai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)為(wei)(wei) 450nA)。下表 1 總結(jie)了(le)這(zhe)兩個(ge)相(xiang)互關聯(lian)的(de) IC 之間的(de)差(cha)別(bie)。

　　結論

　　并聯基(ji)準(zhun)有(you)(you)很多應(ying)用(yong)(yong)，而且視(shi)其功(gong)能的(de)(de)(de)不(bu)(bu)同而不(bu)(bu)同，并聯基(ji)準(zhun)甚至可以用(yong)(yong)來給電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)。不(bu)(bu)過(guo)，這種(zhong)類型的(de)(de)(de)應(ying)用(yong)(yong)有(you)(you)很多缺(que)點，包括大靜態電(dian)(dian)(dian)(dian)流和(he)缺(que)乏電(dian)(dian)(dian)(dian)池(chi)保護功(gong)能。現(xian)在，有(you)(you)了合適(shi)的(de)(de)(de) DC-DC 轉換器或電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)器，因此(ci)可以對(dui)低功(gong)率能量(liang)收集應(ying)用(yong)(yong)進(jin)行查驗了。凌力爾特公司開發了 LTC4070 和(he) LTC4071 并聯充(chong)電(dian)(dian)(dian)(dian)器系統，這兩款器件適(shi)用(yong)(yong)于鋰離子 / 聚合物電(dian)(dian)(dian)(dian)池(chi)、幣形電(dian)(dian)(dian)(dian)池(chi)、薄膜電(dian)(dian)(dian)(dian)池(chi)和(he)電(dian)(dian)(dian)(dian)池(chi)組(zu)(zu)，可為具有(you)(you)低功(gong)率電(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)領先應(ying)用(yong)(yong)提供一種(zhong)簡單(dan)、有(you)(you)效的(de)(de)(de)電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)和(he)電(dian)(dian)(dian)(dian)池(chi)組(zu)(zu)保護解決方案。