單體鋰離子 （Li-Ion） 電池充電器的選項有很多種。隨著手持設備業務的不斷發展，對電池充電器的要求也不斷增加。要為完成這項工作而選擇正確的集成電路 （IC），我們必須權衡幾個因素。在開始設計以前，我們必須考慮諸如解決方案尺寸、USB標準、充電速率和成本等因素。必須將這些因素按照重要程度依次排列，然后選擇相應的充電器IC。本文中，我們將介紹不同的充電拓撲結構，并研究電池充電器IC的一些特性。此外(wai)，我們(men)還將(jiang)探討一個應用和現有的解(jie)決方案。

　　鋰離子電池充電周期

　　鋰離子電池要求專(zhuan)門的(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)周期，以(yi)實(shi)現(xian)安全(quan)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)并最大化(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)使(shi)(shi)用(yong)時(shi)(shi)間(jian)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)分兩(liang)(liang)個階段：恒定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流 （CC） 和恒定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya) （CV）。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)位(wei)于完全(quan)充(chong)滿電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)以(yi)下(xia)時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流經過穩壓(ya)(ya)(ya)(ya)進入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)。在CC模(mo)式下(xia)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流經過穩壓(ya)(ya)(ya)(ya)達(da)到(dao)兩(liang)(liang)個值之一(yi)。如果(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)非常低(di)，則(ze)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流降低(di)至(zhi)預充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，以(yi)適應電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)并防止電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)損(sun)壞。該閾值因電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)化(hua)學屬性而(er)不(bu)同，一(yi)般取(qu)(qu)決(jue)于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)制(zhi)造廠商(shang)。一(yi)旦電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)升(sheng)至(zhi)預充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)閾值以(yi)上(shang)，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)便升(sheng)至(zhi)快速(su)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)。典(dian)型電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)最大建議快速(su)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流為(wei)1C（C=1 小時(shi)(shi)內耗(hao)盡電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)所需的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流），但該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流也取(qu)(qu)決(jue)地電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)制(zhi)造廠商(shang)。典(dian)型充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流為(wei)~0.8C，目的(de)是最大化(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)使(shi)(shi)用(yong)時(shi)(shi)間(jian)。對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)上(shang)升(sheng)。一(yi)旦電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)升(sheng)至(zhi)穩壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)（一(yi)般為(wei)4.2V），充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流逐漸減少，同時(shi)(shi)對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)進行穩壓(ya)(ya)(ya)(ya)以(yi)防止過充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。在這(zhe)種模(mo)式下(xia)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流逐漸減少，同時(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)阻抗降低(di)。如果(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流降至(zhi)預定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)（一(yi)般為(wei)快速(su)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)10%），則(ze)終止充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。我們一(yi)般不(bu)對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)浮充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，因為(wei)這(zhe)樣會(hui)縮(suo)短電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)使(shi)(shi)用(yong)壽命。圖1 以(yi)圖形方式說明(ming)了典(dian)型的(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)周期。

　　圖1典型鋰離子充電周期

　　線性解決方案(an)與開關模式解決方案(an)對比(bi)

　　將適配器電(dian)壓轉(zhuan)降(jiang)為(wei)電(dian)池電(dian)壓并控(kong)制不同充電(dian)階段(duan)的拓(tuo)撲結構(gou)有兩種(zhong)(zhong)：線性(xing)穩(wen)壓器和(he)電(dian)感開關。這兩種(zhong)(zhong)拓(tuo)撲結構(gou)在體積、效率、解決(jue)方(fang)(fang)案成本和(he)電(dian)磁干擾 （EMI） 輻射方(fang)(fang)面各有優(you)缺(que)點。我們下面介紹(shao)這兩種(zhong)(zhong)拓(tuo)撲結構(gou)的各種(zhong)(zhong)優(you)點和(he)一(yi)些折(zhe)中(zhong)方(fang)(fang)法。

　　一(yi)般(ban)來說(shuo)，電(dian)(dian)(dian)(dian)感開(kai)(kai)關(guan)(guan)是獲得最(zui)高效(xiao)率的(de)(de)(de)最(zui)佳選擇。利(li)用電(dian)(dian)(dian)(dian)阻器(qi)等(deng)檢(jian)測(ce)組(zu)件(jian)，在輸(shu)出(chu)端檢(jian)測(ce)充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)。充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)在CC 模式下(xia)時，電(dian)(dian)(dian)(dian)流(liu)反(fan)饋電(dian)(dian)(dian)(dian)路(lu)(lu)控制(zhi)占(zhan)空比。電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)壓檢(jian)測(ce)反(fan)饋電(dian)(dian)(dian)(dian)路(lu)(lu)控制(zhi)CV 模式下(xia)的(de)(de)(de)占(zhan)空比。根據特性集的(de)(de)(de)不同(tong)，可能會(hui)出(chu)現(xian)其(qi)他一(yi)些控制(zhi)環路(lu)(lu)。我(wo)們將(jiang)在后面詳(xiang)細討論這些環路(lu)(lu)。電(dian)(dian)(dian)(dian)感開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)路(lu)(lu)要求開(kai)(kai)關(guan)(guan)組(zu)件(jian)、整(zheng)流(liu)器(qi)、電(dian)(dian)(dian)(dian)感和輸(shu)入(ru)及輸(shu)出(chu)電(dian)(dian)(dian)(dian)容器(qi)。就許(xu)多(duo)(duo)應用而言，通過選擇一(yi)種將(jiang)開(kai)(kai)關(guan)(guan)組(zu)件(jian)和整(zheng)流(liu)器(qi)都嵌入(ru)到IC 中的(de)(de)(de)器(qi)件(jian)，可以縮小解決方案的(de)(de)(de)尺寸(cun)。根據不同(tong)的(de)(de)(de)負載，這些電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)(de)典型效(xiao)率為80% 到96%。開(kai)(kai)關(guan)(guan)轉換(huan)器(qi)因(yin)其(qi)電(dian)(dian)(dian)(dian)感尺寸(cun)一(yi)般(ban)會(hui)要求更多(duo)(duo)的(de)(de)(de)空間，同(tong)時也更加(jia)昂貴。開(kai)(kai)關(guan)(guan)轉換(huan)器(qi)還會(hui)引起電(dian)(dian)(dian)(dian)感EMI 輻射，以及開(kai)(kai)關(guan)(guan)帶(dai)來的(de)(de)(de)輸(shu)出(chu)端噪聲(sheng)。

　　線性充電器通過(guo)降低(di)旁(pang)路(lu)組(zu)件的(de)輸(shu)(shu)(shu)入電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，降低(di)DC 電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)。這樣做的(de)好處是解決(jue)(jue)(jue)方案只(zhi)要(yao)求三個組(zu)件：旁(pang)路(lu)組(zu)件和輸(shu)(shu)(shu)入/輸(shu)(shu)(shu)出電(dian)(dian)(dian)(dian)(dian)(dian)容。相比(bi)電(dian)(dian)(dian)(dian)(dian)(dian)感開關，線性壓(ya)降穩壓(ya)器(qi) （LDO） 通常為一款(kuan)低(di)成本的(de)解決(jue)(jue)(jue)方案，且噪聲更低(di)。通過(guo)穩壓(ya)旁(pang)路(lu)組(zu)件的(de)電(dian)(dian)(dian)(dian)(dian)(dian)阻來(lai)限制(zhi)進(jin)入電(dian)(dian)(dian)(dian)(dian)(dian)池的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，從(cong)而對(dui)(dui)充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)進(jin)行控制(zhi)。電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)反饋一般來(lai)自充電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)IC 的(de)輸(shu)(shu)(shu)入。對(dui)(dui)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)進(jin)行檢測，以提供CV 反饋。改變旁(pang)路(lu)組(zu)件的(de)電(dian)(dian)(dian)(dian)(dian)(dian)阻，來(lai)維持進(jin)入IC 輸(shu)(shu)(shu)入端的(de)恒(heng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)或者恒(heng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)。器(qi)件的(de)輸(shu)(shu)(shu)入電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)等(deng)于(yu)負載電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)。這就(jiu)是說解決(jue)(jue)(jue)方案的(de)效率(lv)等(deng)于(yu)輸(shu)(shu)(shu)出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)與(yu)輸(shu)(shu)(shu)入電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)比(bi)。LDO 解決(jue)(jue)(jue)方案的(de)缺點是高輸(shu)(shu)(shu)入輸(shu)(shu)(shu)出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)比(bi)時（即低(di)電(dian)(dian)(dian)(dian)(dian)(dian)量情況）效率(lv)較低(di)。所有(you)功(gong)率(lv)都被旁(pang)路(lu)組(zu)件消耗(hao)，其意味(wei)著(zhu)LDO 并(bing)非那些(xie)輸(shu)(shu)(shu)入輸(shu)(shu)(shu)出差較大的(de)高充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)應(ying)用的(de)理想選擇(ze)。這些(xie)高功(gong)耗(hao)應(ying)用要(yao)求散熱，從(cong)而增加了(le)解決(jue)(jue)(jue)方案的(de)尺寸(cun)。

　　功耗及溫升計算

　　其中，η為充電器的效率，而POUT = VOUT × IOUT。利用熱阻，可以計算得到功耗帶來的溫升。每種應用的熱阻都不同，其取決于電路板布局、氣流和封裝等具體參數。我們應該針對終端應用電路板對熱阻建模。請記住，產品說明書中定義的ΘJA 并非這種應用中熱阻的恰當表示方法。

   應該使用什么樣的拓撲(pu)？

　　您需要研究的第一個參數是充電電流。對于一些小型應用來說，例如：充電電流介于25Ma 到150mA 之間的藍牙TM耳機等，最佳解決方案幾乎都是線性充電器。這些應用一般都具有非常小的體積，無法為開關的更多組件提供額外空間。另外，由于其非常低的功耗要求，功耗帶來的溫升可以忽略不計。對于手機應用來說，充電電流一般在350-700mA 范圍以內。在這種范圍中，很多時候線性解決方案仍然非常有效。由于它們通常都為低成本手機，其成本壓力更大，因此線性充電器便成為一種理想的解決方案。智能手機應用的電池體積較大，且充電電流需求大于1.5A，這時使用開關解決方案則更加合理。1.5A 電流條件下，溫升會非常大。例如，使用一個線性充電器通過5V 適配器對一塊3.6V 電池充電時，效(xiao)(xiao)(xiao)率(lv)為(wei)72%。首先，這(zhe)個(ge)效(xiao)(xiao)(xiao)率(lv)聽起來(lai)似乎不(bu)太壞。如果您(nin)從(cong)功耗(hao)的角(jiao)度(du)(du)來(lai)看它(ta)，這(zhe)種應(ying)用(yong)(yong)(yong)要消耗(hao)約(yue)2W。在(zai)(zai)一(yi)個(ge)熱阻 （ΘJA） 為(wei)40°C/W 的應(ying)用(yong)(yong)(yong)中，芯片溫度(du)(du)上升(sheng)(sheng)80°C。在(zai)(zai)40°C 環(huan)境溫度(du)(du)下，電(dian)路板溫度(du)(du)會(hui)上升(sheng)(sheng)至(zhi)120°C，其對手持設(she)備來(lai)說是不(bu)可接(jie)受的。在(zai)(zai)極低(di)電(dian)池(chi)電(dian)壓（即(ji)3 V）下，這(zhe)一(yi)問題甚至(zhi)會(hui)變得極端嚴重。相同(tong)(tong)3V 條件(jian)下，溫度(du)(du)升(sheng)(sheng)至(zhi)120°C。讓我們來(lai)看相同(tong)(tong)條件(jian)下的開(kai)(kai)關解決方(fang)(fang)案(an)，使用(yong)(yong)(yong)一(yi)個(ge)單(dan)體(ti)電(dian)池(chi)IC 充(chong)電(dian)器時，效(xiao)(xiao)(xiao)率(lv)上升(sheng)(sheng)至(zhi)約(yue)85%。使用(yong)(yong)(yong)一(yi)塊3.6V 電(dian)池(chi)時，功耗(hao)低(di)于1W，從(cong)而帶來(lai)40°C 的溫升(sheng)(sheng)。3V 時這(zhe)種改善更加明顯。假設(she)3V 輸出時的效(xiao)(xiao)(xiao)率(lv)為(wei)80%，則(ze)功耗(hao)低(di)于800 mW，因此溫升(sheng)(sheng)會(hui)更低(di)（約(yue)32°C）。這(zhe)些智能手機的體(ti)積一(yi)般可以(yi)容許稍大一(yi)點的解決方(fang)(fang)案(an)，并且能夠承受開(kai)(kai)關模式解決方(fang)(fang)案(an)相關的稍許成(cheng)本(ben)增加。

　　為任務選擇正確的(de)IC

　　在您已經(jing)完成您的(de)初步熱分析并且選好充電(dian)(dian)器(qi)拓撲以(yi)后(hou)，您便(bian)可以(yi)轉到選擇應用(yong)的(de)最佳IC 上來。新型(xing)的(de)電(dian)(dian)池充電(dian)(dian)器(qi)解決(jue)方(fang)案(an)集(ji)(ji)成了許(xu)多特(te)性(xing)，可以(yi)利用(yong)它(ta)們改(gai)善系統的(de)性(xing)能(neng)。諸如輸入過壓(ya)保護、電(dian)(dian)源路(lu)徑管(guan)理 （PPM）、VIN_DPM、散熱穩(wen)壓(ya)、負(fu)溫度系數熱敏電(dian)(dian)阻 （NTC） 監測和USB 充電(dian)(dian)等(deng)特(te)性(xing)，都(dou)被集(ji)(ji)成到許(xu)多電(dian)(dian)池充電(dian)(dian)器(qi)IC 中。大多數單體電(dian)(dian)池充電(dian)(dian)器(qi)解決(jue)方(fang)案(an)都(dou)已將要求(qiu)FET 集(ji)(ji)成到了器(qi)件中，旨在節省電(dian)(dian)路(lu)板面積。

　　輸入(ru)(ru)過壓保(bao)護（單輸入(ru)(ru)與雙輸入(ru)(ru)對比）

　　在當(dang)今的(de)(de)(de)市場(chang)(chang)(chang)上，USB 電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)已(yi)經成為(wei)(wei)最(zui)為(wei)(wei)常見的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，因此通過(guo)(guo)USB 電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)充(chong)電(dian)(dian)(dian)(dian)(dian)已(yi)經成為(wei)(wei)一(yi)(yi)(yi)種(zhong)必然性。市場(chang)(chang)(chang)已(yi)經從使(shi)(shi)(shi)用(yong)(yong)專門AC 適(shi)配器(qi)和單(dan)獨USB 接(jie)口的(de)(de)(de)初始雙(shuang)輸入(ru)轉變(bian)為(wei)(wei)將一(yi)(yi)(yi)個USB 接(jie)口既(ji)作為(wei)(wei)墻上電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)合器(qi)接(jie)口使(shi)(shi)(shi)用(yong)(yong)，也作為(wei)(wei)使(shi)(shi)(shi)用(yong)(yong)相同線纜的(de)(de)(de)USB 數據輸入(ru)接(jie)口的(de)(de)(de)單(dan)輸入(ru)解(jie)(jie)決(jue)方(fang)(fang)案(an)(an)(an)(an)。這樣(yang)便(bian)導致一(yi)(yi)(yi)種(zhong)從雙(shuang)輸入(ru)解(jie)(jie)決(jue)方(fang)(fang)案(an)(an)(an)(an)向(xiang)單(dan)輸入(ru)解(jie)(jie)決(jue)方(fang)(fang)案(an)(an)(an)(an)的(de)(de)(de)轉移。單(dan)輸入(ru)在接(jie)口方(fang)(fang)面存在許(xu)多(duo)挑戰。由于存在如此多(duo)的(de)(de)(de)配件市場(chang)(chang)(chang)適(shi)配器(qi)解(jie)(jie)決(jue)方(fang)(fang)案(an)(an)(an)(an)和一(yi)(yi)(yi)種(zhong)通用(yong)(yong)接(jie)口，輸入(ru)端必須要能夠在無損壞的(de)(de)(de)情況下承受更高的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓。由于電(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)器(qi)始終連接(jie)到輸入(ru)端，因此充(chong)電(dian)(dian)(dian)(dian)(dian)器(qi)對所有(you)下游電(dian)(dian)(dian)(dian)(dian)路實(shi)施(shi)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)壓狀態保護(hu)是有(you)道理的(de)(de)(de)。為(wei)(wei)了(le)(le)實(shi)施(shi)這一(yi)(yi)(yi)功能，市場(chang)(chang)(chang)上出(chu)現(xian)了(le)(le)許(xu)多(duo)能夠承受20V 甚至30V 電(dian)(dian)(dian)(dian)(dian)壓的(de)(de)(de)解(jie)(jie)決(jue)方(fang)(fang)案(an)(an)(an)(an)。另外，這些器(qi)件都具有(you)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)壓保護(hu) （OVP） 電(dian)(dian)(dian)(dian)(dian)路，其(qi)在輸入(ru)超出(chu)OVP 閾值時阻止器(qi)件運行。這樣(yang)便(bian)進一(yi)(yi)(yi)步(bu)保護(hu)了(le)(le)下游電(dian)(dian)(dian)(dian)(dian)路，使(shi)(shi)(shi)其(qi)免受潛在的(de)(de)(de)瞬態過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)壓狀態損壞。

　　目前(qian)，隨(sui)著(zhu)綠色輸入（即太(tai)陽能電池）或無線充電的(de)出現(xian)，應(ying)用(yong)又再(zai)一次(ci)向雙輸入要(yao)求(qiu)轉移。根據具體的(de)應(ying)用(yong)要(yao)求(qiu)，兩種配(pei)置結構都可(ke)以使用(yong)。

　　電(dian)源路徑管理/最(zui)小系統電(dian)壓

　　電池充電器的一般方法是將系統直接連接到電池，讓充電器同時為電池和系統供電。然后，對系統的總電流進行穩壓，這樣做存在幾個問題。特別是低電池電量啟動、終止干擾和早期計時器超時等問題。電源路徑管理通過對電池電流和系統電流進行分別(bie)監測，消(xiao)除了這些問題［2］。

　　圖 2 傳統拓撲結(jie)構舉例

　　圖 3 電源路徑拓(tuo)撲結構舉(ju)例

　　最低系統電壓

　　使用傳統方法時，系統電壓始終與電池相同。因此，電池深度放電時，在電池充電到某個可用電平以前系統都不會啟動。利用PPM，可對系統電壓單獨穩壓，將其與電池電壓區分開來。這就意味著可以實現最低系統電壓，其與電池電壓無關。對用戶而言，這就意味著連接適配器的同時他們便可以使用設備，假設條件是其具有足夠的功率來驅動系統。如bq25060 等器件就具有這種功能。

   更短的充電時間

　　由于(yu)系(xi)統(tong)電(dian)(dian)(dian)(dian)流(liu)(liu)和(he)(he)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)是單(dan)獨編(bian)程(cheng)(cheng)的(de)，因此(ci)可以使用(yong)適配器的(de)滿功率，其與電(dian)(dian)(dian)(dian)池的(de)容量和(he)(he)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)的(de)大小均(jun)無關。傳統(tong)拓撲結構中，充(chong)電(dian)(dian)(dian)(dian)器的(de)輸出電(dian)(dian)(dian)(dian)流(liu)(liu)必須設(she)定為(wei)最大充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)，以應對(dui)沒有系(xi)統(tong)負(fu)載(zai)的(de)情(qing)況。當系(xi)統(tong)中有負(fu)載(zai)時，由于(yu)系(xi)統(tong)吸收可用(yong)電(dian)(dian)(dian)(dian)流(liu)(liu)，有效(xiao)(xiao)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)降低(di)。例(li)如(ru)，一個(ge)使用(yong)900 mA 適配器和(he)(he)500 mAhr 電(dian)(dian)(dian)(dian)池的(de)系(xi)統(tong)，使用(yong)傳統(tong)方法可以編(bian)程(cheng)(cheng)500 mA 的(de)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)。如(ru)果(guo)系(xi)統(tong)負(fu)載(zai)為(wei)200 mA，有效(xiao)(xiao)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)僅為(wei)300 mA，充(chong)電(dian)(dian)(dian)(dian)時間幾乎翻了一翻。如(ru)果(guo)使用(yong)PPM 來研究這(zhe)一相同案例(li)，輸入電(dian)(dian)(dian)(dian)流(liu)(liu)限制設(she)定為(wei)900 mA。這(zhe)樣便允(yun)許全部500 mA充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)，且擁(yong)有多達400 mA 的(de)額外系(xi)統(tong)電(dian)(dian)(dian)(dian)流(liu)(liu)。

　　終(zhong)止和早(zao)期(qi)計時器超時

　　在(zai)對總電(dian)(dian)(dian)(dian)(dian)流進(jin)行穩壓的傳統(tong)系(xi)(xi)(xi)統(tong)中，電(dian)(dian)(dian)(dian)(dian)流在(zai)電(dian)(dian)(dian)(dian)(dian)池和(he)負(fu)載之間共用。如果系(xi)(xi)(xi)統(tong)負(fu)載足(zu)夠(gou)大到(dao)從電(dian)(dian)(dian)(dian)(dian)池拉取充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流，且在(zai)計(ji)時(shi)器(qi)(qi)超時(shi)以前電(dian)(dian)(dian)(dian)(dian)池不(bu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，則計(ji)時(shi)器(qi)(qi)會出現偽超時(shi)。另外，如果系(xi)(xi)(xi)統(tong)電(dian)(dian)(dian)(dian)(dian)流絕對不(bu)會降至設定(ding)終(zhong)(zhong)止(zhi)電(dian)(dian)(dian)(dian)(dian)流以下(xia)，則永遠不(bu)會終(zhong)(zhong)止(zhi)。電(dian)(dian)(dian)(dian)(dian)源(yuan)路徑管理通(tong)過單(dan)獨監測充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流，并動(dong)態地使用可(ke)穩壓計(ji)時(shi)器(qi)(qi)（通(tong)過減(jian)少充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流進(jin)行穩壓），防止(zhi)這(zhe)些條(tiao)件(jian)出現。就終(zhong)(zhong)止(zhi)問題而言，單(dan)獨對充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流進(jin)行監測，可(ke)讓終(zhong)(zhong)止(zhi)條(tiao)件(jian)測定(ding)變得容易。

　　基(ji)于輸(shu)入(ru)電壓的動(dong)態(tai)電源管理 （VIN-DPM）

　　為了防止出現輸入源超負載的欠壓狀態，一些器件實施了基于輸入電壓的動態電源管理 （VIN-DPM）。這種環路降低輸入電流限制來防止輸入崩潰。VIN-DPM 環路對輸入電壓進行有效的穩壓，來最大化電源的電流。圖4 顯示了在無VIN-DPM 保護的情況下USB 端口的超負載結果。請注意，輸入電壓降至電源狀態良好閾值以下時，充電器關閉。這樣便關閉了電源負載，并允許輸入電壓恢復，從而開啟充電器。這種開/關脈(mo)沖發生并不是我們(men)想要(yao)的。

　　圖 4 無 VIN-DPM 情況(kuang)下的輸入(ru)崩潰

　　VIN-DPM 通過限(xian)制(zhi)輸(shu)入(ru)電流阻止脈沖發生，從而防(fang)止輸(shu)入(ru)源崩潰。圖5 顯示了超負載USB 端(duan)口的(de)結(jie)果。VIN-DPM 功能開始(shi)生效，降(jiang)低輸(shu)入(ru)電流限(xian)制(zhi)，從而防(fang)止輸(shu)入(ru)源崩潰。

　　圖 5 使用(yong)VIN-DPM的輸入超負(fu)載保護

　　NTC 監測（包(bao)括(kuo)JEITA）

　　通(tong)過(guo)充電(dian)(dian)期間的(de)監(jian)測防(fang)止電(dian)(dian)池(chi)組損壞甚至是(shi)爆炸時(shi)，電(dian)(dian)池(chi)溫度(du)極為重(zhong)要。一般來說(shuo)，通(tong)過(guo)對(dui)集成到(dao)電(dian)(dian)池(chi)組中或者靠近系統板上電(dian)(dian)池(chi)組安(an)裝的(de)NTC 熱敏電(dian)(dian)阻(zu)進行(xing)監(jian)測，來完成這項(xiang)工作。許多充電(dian)(dian)器(qi)都具有集成到(dao)IC 中的(de)NTC 監(jian)測功能。如果電(dian)(dian)池(chi)溫度(du)處在(zai)某(mou)些(xie)非(fei)安(an)全溫度(du)下時(shi)，這些(xie)IC 便對(dui)溫度(du)和禁用充電(dian)(dian)電(dian)(dian)流(liu)進行(xing)監(jian)測。

　　一種新興的電池充電標準是日本電池溫度標準 （JEITA）。這種標準規定了一些需降低充電電壓或者電流以提供更安全運行的中間溫度。該JEITA標準在許多充電器IC 中也很容易實施。例如，單輸入單體鋰離子電池充電器集成了一種(zhong)無(wu)需(xu)主(zhu)機(ji)(ji)關聯的(de)獨立(li)解決方(fang)(fang)案。對于NTC 受主(zhu)機(ji)(ji)監測的(de)系(xi)統來(lai)說(shuo)，許多(duo)IC 都(dou)提供(gong)了非常簡單的(de)實(shi)施。I2C 接口(kou)允許用(yong)戶動態地改變充電電壓和(he)充電電流(liu)，使用(yong)具有(you)(you)這(zhe)種(zhong)接口(kou)的(de)充電器(qi)時，主(zhu)機(ji)(ji)根(gen)據電池(chi)溫度來(lai)修改充電參數。這(zhe)種(zhong)方(fang)(fang)法(fa)在(zai)沒(mei)有(you)(you)硬件改動的(de)情況(kuang)下，在(zai)為不同(tong)平臺和(he)電池(chi)設置要(yao)求的(de)溫度閾值(zhi)方(fang)(fang)面擁有(you)(you)一定(ding)的(de)靈活(huo)性。

　　USB 充電標準

　　USB 充電時，可以使用許多充電器IC，它們都結(jie)合了USB100和USB500 電(dian)流限制。通過USB 充電(dian)器輸出(chu)運行所有下游(you)電(dian)路，讓廣大(da)設計人員能夠確保不超出(chu)USB 電(dian)流限制。

　　額外功率輸出

　　隨著USB 充電的流行，許多應用都要求一個USB PHY 或者USB 收發器與主機枚舉。因此，這些器件通常直接連接到VBUS 電源，從而要求過電壓保護。因此，許多充電器IC 都集成了一個連(lian)接電(dian)(dian)(dian)源(yuan)并通(tong)過(guo)電(dian)(dian)(dian)源(yuan)供(gong)電(dian)(dian)(dian)的(de)5V LDO。每當連(lian)接一個有效電(dian)(dian)(dian)源(yuan)時(shi)，這種(zhong)輸出便(bian)有效。5V LDO 穩(wen)壓電(dian)(dian)(dian)壓保護USB 電(dian)(dian)(dian)路免受未穩(wen)壓適配器(qi)和其(qi)他(ta)過(guo)電(dian)(dian)(dian)壓狀(zhuang)態的(de)損害。

　　　為單體鋰離子電池充電有很多種方法。我們必須對諸如充電電流、可用空間、USB 標準、成本和特性集等要求進行研究，以選擇最佳的解決方案。首先按照重要程度把這些要求排列出來，然后選擇最適合這些要求的拓撲結構。請一定要考慮散熱因素，最后為每種輸出選擇最具成本效益的解決方案。在這些簡單步驟之后，您的電池充電器設計應該(gai)就會變得(de)簡單了。