從(cong)為(wei)平(ping)板電(dian)(dian)腦(nao)或(huo)智能手機電(dian)(dian)池充(chong)電(dian)(dian)到(dao)為(wei)膝上型(xing)電(dian)(dian)腦(nao)或(huo)家用(yong)(yong)路由(you)器供(gong)電(dian)(dian)，電(dian)(dian)源(yuan)適(shi)配(pei)(pei)(pei)(pei)器長期以來都(dou)是人們日常生活的(de)必要組(zu)成(cheng)部分(fen)。對于(yu)將電(dian)(dian)源(yuan)適(shi)配(pei)(pei)(pei)(pei)器與其產品(pin)搭配(pei)(pei)(pei)(pei)到(dao)一起的(de)消費電(dian)(dian)子(zi)原設(she)備制(zhi)造商（OEM）而言，需(xu)要因(yin)應兩(liang)項關鍵推(tui)動因(yin)素，即(ji)確保提(ti)供(gong)高能效(xiao)等級并滿足安全規范，同時還需(xu)提(ti)供(gong)緊(jin)湊的(de)外形因(yin)數(shu)。近年來，由(you)于(yu)結合(he)了政府(fu)法(fa)規及美國“能源(yuan)之星(xing)”、歐盟生態設(she)計(ji)指令(ling)及中國標準(zhun)化研(yan)究院（CNIS）等能效(xiao)項目(mu)，業界非常注重通過減(jian)小待機模式(shi)下(xia)的(de)使用(yong)(yong)的(de)電(dian)(dian)能來降(jiang)低適(shi)配(pei)(pei)(pei)(pei)器的(de)總體(ti)能耗等級。本文將探(tan)討推(tui)動最新(xin)要求的(de)新(xin)興(xing)技術趨勢，包括(kuo)要求減(jian)少(shao)使用(yong)(yong)的(de)外部元(yuan)器件數(shu)量、使設(she)計(ji)更時髦輕薄的(de)工藝(yi)。

　　待機(ji)能(neng)(neng)耗(hao)(hao)(hao)有時候也稱(cheng)作(zuo)“吸血鬼能(neng)(neng)耗(hao)(hao)(hao)”或是“虛負載”,指的是電(dian)(dian)子設(she)備及電(dian)(dian)器在關斷電(dian)(dian)源(yuan)但仍然插在電(dian)(dian)源(yuan)插座上時消耗(hao)(hao)(hao)的電(dian)(dian)能(neng)(neng)。以(yi)美國為例，待機(ji)能(neng)(neng)耗(hao)(hao)(hao)約占(zhan)美國家庭平均(jun)總能(neng)(neng)耗(hao)(hao)(hao)約10%.這相(xiang)當(dang)于令人驚愕的129太瓦時（即為1,290億千瓦時）的電(dian)(dian)能(neng)(neng)，或者是36座400兆瓦發(fa)電(dian)(dian)廠輸出的電(dian)(dian)能(neng)(neng)，導致每年排放7,500萬噸二氧化碳。

　　在(zai)(zai)美國(guo)，2008年(nian)7月(yue)1日生(sheng)效的(de)現行聯邦標(biao)(biao)(biao)準(zhun)要求(qiu)(qiu)功率低于250 W的(de)電(dian)(dian)源(yuan)(yuan)空(kong)載(zai)能(neng)(neng)耗(hao)低于500 mW.最(zui)近，美國(guo)能(neng)(neng)源(yuan)(yuan)部（DOE）提出了更(geng)嚴格(ge)的(de)電(dian)(dian)池充電(dian)(dian)器(qi)及(ji)(ji)電(dian)(dian)子產(chan)品(pin)(pin)電(dian)(dian)源(yuan)(yuan)能(neng)(neng)效標(biao)(biao)(biao)準(zhun)，并將于2013年(nian)7月(yue)1日生(sheng)效。根據新標(biao)(biao)(biao)準(zhun)，銘牌(pai)輸出功率介于49至250 W之間（典型(xing)筆記本視頻器(qi)功率位(wei)于此(ci)范(fan)圍）的(de)交流-直流（AC-DC）外部電(dian)(dian)源(yuan)(yuan)的(de)最(zui)大(da)空(kong)載(zai)能(neng)(neng)耗(hao)必須低于0.210 W.然而(er)，這(zhe)些國(guo)家標(biao)(biao)(biao)準(zhun)通(tong)常落后于其它標(biao)(biao)(biao)準(zhun)及(ji)(ji)市場(chang)要求(qiu)(qiu)。美國(guo)1975年(nian)能(neng)(neng)源(yuan)(yuan)政策及(ji)(ji)節(jie)能(neng)(neng)法案（EPCA）規定：任何新的(de)節(jie)能(neng)(neng)標(biao)(biao)(biao)準(zhun)的(de)制定必須旨在(zai)(zai)提供最(zui)大(da)程度的(de)能(neng)(neng)效提升，不僅要在(zai)(zai)技術(shu)上可行，也(ye)要具備(bei)經濟(ji)合理性。因此(ci)，這(zhe)些國(guo)家標(biao)(biao)(biao)準(zhun)通(tong)常并不代(dai)表“一(yi)流的(de)”性能(neng)(neng)。諸(zhu)多電(dian)(dian)源(yuan)(yuan)制造商要求(qiu)(qiu)將空(kong)載(zai)能(neng)(neng)耗(hao)限制到盡(jin)可能(neng)(neng)地低，從(cong)而(er)將其產(chan)品(pin)(pin)與競爭產(chan)品(pin)(pin)區別開來。

　　圖1:美國(guo)能源部提出的(de)AC-DC外部電(dian)源節能標準

　　在能(neng)效標準(zhun)上最(zui)為(wei)進取的(de)(de)政府機(ji)構很可(ke)能(neng)是美(mei)國加(jia)州(zhou)(zhou)(zhou)。電源制造(zao)商可(ke)不想提供(gong)(gong)僅針對加(jia)州(zhou)(zhou)(zhou)的(de)(de)特(te)定(ding)型(xing)號(hao)產品，因此(ci)，加(jia)州(zhou)(zhou)(zhou)標準(zhun)的(de)(de)實際影(ying)響范(fan)(fan)圍(wei)要(yao)廣得多。例(li)如，美(mei)國加(jia)州(zhou)(zhou)(zhou)在2012年1月(yue)出臺的(de)(de)新的(de)(de)電器(qi)能(neng)效規范(fan)(fan)將電池充(chong)電器(qi)系統作為(wei)重要(yao)焦(jiao)點。加(jia)州(zhou)(zhou)(zhou)每年有(you)超過1.7億(yi)(yi)個(ge)充(chong)電器(qi)被(bei)用于充(chong)電，根(gen)據(ju)推(tui)測，在此(ci)特(te)別領域提升(sheng)能(neng)效，每年將可(ke)節省2,200吉瓦(wa)時（即22億(yi)(yi)千瓦(wa)時）的(de)(de)電能(neng)。這(zhe)(zhe)些電路(lu)足夠(gou)為(wei)35萬個(ge)家庭供(gong)(gong)電，相當于為(wei)住宅(zhai)/商業用電賬單每年節省3.06億(yi)(yi)美(mei)元。美(mei)國加(jia)州(zhou)(zhou)(zhou)能(neng)源委(wei)員會（CEC）實施的(de)(de)這(zhe)(zhe)些能(neng)效規范(fan)(fan)要(yao)求手機(ji)、個(ge)人照護設備(bei)及電動工(gong)具所(suo)(suo)使用的(de)(de)所(suo)(suo)有(you)消費類充(chong)電器(qi)在2013年2月(yue)前必須(xu)遵(zun)從，而工(gong)業類充(chong)電器(qi)須(xu)在未來12個(ge)月(yue)內遵(zun)從。美(mei)國其他(ta)幾個(ge)州(zhou)(zhou)(zhou)希望遵(zun)循加(jia)州(zhou)(zhou)(zhou)降低待機(ji)能(neng)耗(hao)限(xian)制值的(de)(de)范(fan)(fan)例(li)。

　　圖2:電動工具所用的典(dian)型老(lao)式充電系(xi)統

　　圖2介紹了(le)過(guo)去(qu)常用的(de)基(ji)本充(chong)電(dian)(dian)器(qi)系(xi)統電(dian)(dian)路圖。此特別案例使(shi)(shi)用鎳鉻（NiCd）電(dian)(dian)池(chi)來為(wei)(wei)電(dian)(dian)動(dong)工(gong)具(ju)充(chong)電(dian)(dian)。電(dian)(dian)池(chi)在1小時(shi)內的(de)電(dian)(dian)量(liang)標為(wei)(wei)C.例如，以0.5 C的(de)充(chong)電(dian)(dian)速(su)率來為(wei)(wei)額定容量(liang)600 mAh的(de)電(dian)(dian)池(chi)充(chong)電(dian)(dian)，使(shi)(shi)用300 mA充(chong)電(dian)(dian)電(dian)(dian)流要經(jing)歷超(chao)過(guo)2小時(shi)才能完全充(chong)滿電(dian)(dian)池(chi)。

　　圖2中的(de)電(dian)路能(neng)(neng)以0.1 C的(de)恒(heng)定充(chong)電(dian)速率。由于充(chong)電(dian)器(qi)的(de)60 Hz變壓器(qi)的(de)設計(ji)意圖是(shi)維持低(di)成本(ben)，而(er)非提供高能(neng)(neng)效(xiao)等級(ji)，空(kong)載能(neng)(neng)耗通常將(jiang)高于0.5 W,如此高的(de)空(kong)載能(neng)(neng)耗不(bu)再(zai)能(neng)(neng)夠令(ling)人接受。早期想法是(shi)使充(chong)電(dian)器(qi)能(neng)(neng)效(xiao)更高，但不(bu)注(zhu)意事實上充(chong)電(dian)后(hou)電(dian)路會持續無限期地浪(lang)費(fei)電(dian)能(neng)(neng)。這已(yi)經被證明(ming)是(shi)一(yi)種有點誤(wu)導(dao)的(de)視(shi)角。

　　即便是(shi)當(dang)今市場上的許(xu)多(duo)充(chong)電(dian)(dian)(dian)器，也仍然(ran)缺乏檢(jian)測電(dian)(dian)(dian)池是(shi)否完(wan)(wan)全(quan)充(chong)滿的能(neng)力，且因此在充(chong)電(dian)(dian)(dian)過程(cheng)完(wan)(wan)成后仍然(ran)持續提供電(dian)(dian)(dian)能(neng)給(gei)電(dian)(dian)(dian)池，因而浪(lang)費電(dian)(dian)(dian)能(neng)（釋放為熱(re)量）。通過使用可以關(guan)閉(bi)完(wan)(wan)全(quan)充(chong)滿之電(dian)(dian)(dian)池的充(chong)電(dian)(dian)(dian)通道，電(dian)(dian)(dian)能(neng)就不(bu)會無謂(wei)地浪(lang)費，電(dian)(dian)(dian)池也不(bu)會置于損壞(huai)的風險(xian)。

    提供低(di)待(dai)機(ji)能耗工作(zuo)的創新方案

　　家(jia)庭中一項常見的(de)待機能耗源(yuan)頭就是筆(bi)記(ji)本(ben)適(shi)配(pei)器。這些適(shi)配(pei)器相當多的(de)使(shi)用(yong)時間是在筆(bi)記(ji)本(ben)電腦斷開連接或關斷的(de)情況下(xia)在桌(zhuo)子底下(xia)度過的(de)。如今(jin)典型的(de)市售筆(bi)記(ji)本(ben)適(shi)配(pei)器在空(kong)(kong)載條件下(xia)約消(xiao)耗300 mW至500 mW的(de)能耗。然而，許多領先制造商如今(jin)要(yao)求(qiu)下(xia)一代筆(bi)記(ji)本(ben)適(shi)配(pei)器的(de)空(kong)(kong)載能耗限(xian)制到低于30 mW,從而使(shi)其產品(pin)與競爭(zheng)產品(pin)區域開來。圖3顯示了65 W筆(bi)記(ji)本(ben)適(shi)配(pei)器用(yong)下(xia)一代充(chong)電系統的(de)簡化示例。此電路最重要(yao)的(de)元器件就是固定(ding)頻率(lv)電流(liu)模(mo)式控制器IC及次級(ji)端(duan)開關電源(yuan)（SMPS）控制器IC.

　　圖(tu)(tu)3:帶空(kong)載檢測功(gong)能(neng)的先進充電電路簡化(hua)電路圖(tu)(tu)

　　這(zhe)示例中指定(ding)的(de)(de)固定(ding)頻(pin)率電(dian)(dian)(dian)(dian)(dian)流(liu)模式(shi)控制器(qi)（即安(an)森美半導體的(de)(de)NCP1246）經過了(le)專門(men)優化，在(zai)空(kong)載(zai)及輕載(zai)條(tiao)件下消(xiao)(xiao)耗(hao)極(ji)低的(de)(de)能耗(hao)。交(jiao)流(liu)-直流(liu)（AC-DC）電(dian)(dian)(dian)(dian)(dian)源空(kong)載(zai)條(tiao)件下輸入能耗(hao)的(de)(de)其中一項(xiang)主(zhu)要來(lai)源是(shi)X2電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)放電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路。典型(xing)適配(pei)器(qi)包含(han)高(gao)壓(ya)X2電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)，它連接至(zhi)交(jiao)流(liu)輸入端，作為電(dian)(dian)(dian)(dian)(dian)磁干擾（EMI）濾波器(qi)的(de)(de)一部(bu)分。出(chu)于(yu)安(an)全原因，強(qiang)制要求此(ci)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)在(zai)從墻上拔(ba)出(chu)適配(pei)器(qi)插頭(tou)后的(de)(de)1秒時(shi)(shi)間內(nei)放電(dian)(dian)(dian)(dian)(dian)至(zhi)安(an)全電(dian)(dian)(dian)(dian)(dian)壓(ya)電(dian)(dian)(dian)(dian)(dian)平。否則，接觸交(jiao)流(liu)插頭(tou)的(de)(de)扁腳（prong）就(jiu)面(mian)臨電(dian)(dian)(dian)(dian)(dian)擊的(de)(de)危險。符合此(ci)要求的(de)(de)標準(zhun)方法(fa)是(shi)使用一串與(yu)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)并聯的(de)(de)高(gao)阻抗泄(xie)放電(dian)(dian)(dian)(dian)(dian)阻。當用于(yu)230 Vac應用時(shi)(shi)，這(zhe)恒(heng)定(ding)的(de)(de)電(dian)(dian)(dian)(dian)(dian)阻型(xing)消(xiao)(xiao)耗(hao)源約消(xiao)(xiao)耗(hao)25 mW輸入能耗(hao)。當顧及到空(kong)載(zai)能耗(hao)時(shi)(shi)，這(zhe)25 mW就(jiu)變得相(xiang)當大(da)了(le)。NCP1246解決此(ci)問(wen)題的(de)(de)方法(fa)是(shi)加入帶有(you)(you)源放電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路的(de)(de)內(nei)置(zhi)交(jiao)流(liu)線路檢測器(qi)。這(zhe)控制器(qi)在(zai)檢測到不再存在(zai)交(jiao)流(liu)信號時(shi)(shi)，激活內(nei)置(zhi)開關來(lai)使電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)放電(dian)(dian)(dian)(dian)(dian)。有(you)(you)了(le)這(zhe)個功能，就(jiu)不再需要泄(xie)放電(dian)(dian)(dian)(dian)(dian)阻了(le)，消(xiao)(xiao)除了(le)恒(heng)定(ding)的(de)(de)25 mW能耗(hao)源頭(tou)。

　　次(ci)級(ji)(ji)端(duan)(duan)開(kai)關電(dian)(dian)(dian)源(yuan)(yuan)控(kong)(kong)制(zhi)(zhi)器(qi)(qi)（即(ji)安森(sen)美半導(dao)(dao)體的(de)(de)(de)NCP4354）是NCP1246的(de)(de)(de)伴侶IC,能(neng)夠檢測空載(zai)條件，并(bing)使(shi)電(dian)(dian)(dian)源(yuan)(yuan)進入低能(neng)耗(hao)關閉(bi)模(mo)式(shi)。在關閉(bi)模(mo)式(shi)期間，初級(ji)(ji)端(duan)(duan)控(kong)(kong)制(zhi)(zhi)器(qi)(qi)停止工(gong)作(zuo)，能(neng)量由輸(shu)出(chu)(chu)電(dian)(dian)(dian)容(rong)提供(gong)(gong)。適(shi)配(pei)器(qi)(qi)的(de)(de)(de)輸(shu)出(chu)(chu)電(dian)(dian)(dian)壓開(kai)始下(xia)降，因為(wei)初級(ji)(ji)端(duan)(duan)不再在存在開(kai)關工(gong)作(zuo)。這并(bing)不構成什(shen)么問題(ti)，因為(wei)適(shi)配(pei)器(qi)(qi)在此模(mo)式(shi)下(xia)不再連接至(zhi)筆記本電(dian)(dian)(dian)腦(nao)。輸(shu)出(chu)(chu)電(dian)(dian)(dian)壓被(bei)允許下(xia)降至(zhi)某個可調(diao)節電(dian)(dian)(dian)平，直到NCP4354通知初級(ji)(ji)端(duan)(duan)重啟，重新為(wei)輸(shu)出(chu)(chu)電(dian)(dian)(dian)容(rong)充電(dian)(dian)(dian)并(bing)因此維(wei)持工(gong)作(zuo)。當(dang)適(shi)配(pei)器(qi)(qi)重新連接至(zhi)電(dian)(dian)(dian)池時，NCP4354控(kong)(kong)制(zhi)(zhi)器(qi)(qi)自動(dong)重啟初級(ji)(ji)端(duan)(duan)控(kong)(kong)制(zhi)(zhi)器(qi)(qi)。能(neng)僅以一(yi)顆光耦提供(gong)(gong)反饋控(kong)(kong)制(zhi)(zhi)及(ji)導(dao)(dao)通/關閉(bi)信(xin)號。當(dang)在此類電(dian)(dian)(dian)路中一(yi)起(qi)使(shi)用(yong)時，NCP1246和NCP4354能(neng)夠采用(yong)美國規(gui)格的(de)(de)(de)交(jiao)流(liu)(liu)主電(dian)(dian)(dian)源(yuan)(yuan)提供(gong)(gong)低于10 mW的(de)(de)(de)空載(zai)能(neng)耗(hao)，且在寬交(jiao)流(liu)(liu)主電(dian)(dian)(dian)源(yuan)(yuan)電(dian)(dian)(dian)壓范圍下(xia)提供(gong)(gong)低于20 mW的(de)(de)(de)空載(zai)能(neng)耗(hao)。

　　圖4:65 W適配器電(dian)路圖

　　雖然許(xu)多消費(fei)電(dian)子(zi)OEM生產高(gao)能效產品(pin)，但他們(men)常常會對低能耗的充(chong)電(dian)系統感到(dao)失(shi)望。如(ru)今已經(jing)出現重要(yao)進(jin)展(zhan)，電(dian)池充(chong)電(dian)器可以消耗更少電(dian)能，同時提供市場所(suo)要(yao)求的高(gao)性能基(ji)準。諸如(ru)本(ben)文所(suo)介(jie)紹的系統致力于滿足這些標準，并降(jiang)低系統復(fu)雜度、節省珍貴的電(dian)路(lu)板空間及使物料(liao)單(dan)（BOM）成本(ben)受到(dao)控(kong)制。