從為(wei)平板電(dian)(dian)腦(nao)或智能(neng)手機電(dian)(dian)池充電(dian)(dian)到為(wei)膝上型電(dian)(dian)腦(nao)或家用路由器(qi)供電(dian)(dian)，電(dian)(dian)源(yuan)適配(pei)器(qi)長(chang)期以來都是人(ren)們(men)日常生活的(de)(de)必要組成部(bu)分。對于將(jiang)電(dian)(dian)源(yuan)適配(pei)器(qi)與其(qi)產品搭配(pei)到一起的(de)(de)消費(fei)電(dian)(dian)子原設備制(zhi)造商（OEM）而言，需要因應兩(liang)項(xiang)關鍵推(tui)動因素，即確(que)保提供高能(neng)效等(deng)級并(bing)滿足安全規范，同時(shi)還需提供緊湊的(de)(de)外(wai)(wai)形因數。近年來，由于結合了政府法規及(ji)美國“能(neng)源(yuan)之星”、歐盟生態設計(ji)指(zhi)令(ling)及(ji)中國標(biao)準(zhun)化(hua)研(yan)究(jiu)院（CNIS）等(deng)能(neng)效項(xiang)目，業界非常注重通過減(jian)小待機模式下的(de)(de)使(shi)用的(de)(de)電(dian)(dian)能(neng)來降低適配(pei)器(qi)的(de)(de)總體能(neng)耗等(deng)級。本文將(jiang)探討(tao)推(tui)動最新要求(qiu)的(de)(de)新興技術趨勢，包括(kuo)要求(qiu)減(jian)少使(shi)用的(de)(de)外(wai)(wai)部(bu)元器(qi)件數量、使(shi)設計(ji)更時(shi)髦(mao)輕薄的(de)(de)工藝。

　　待機(ji)能(neng)耗(hao)(hao)有時(shi)(shi)候(hou)也稱作“吸(xi)血鬼能(neng)耗(hao)(hao)”或是(shi)(shi)“虛(xu)負載”,指的(de)(de)是(shi)(shi)電子設(she)備(bei)及電器在關(guan)斷電源但仍然(ran)插在電源插座(zuo)上時(shi)(shi)消耗(hao)(hao)的(de)(de)電能(neng)。以(yi)美國為例，待機(ji)能(neng)耗(hao)(hao)約(yue)占美國家(jia)庭(ting)平(ping)均總能(neng)耗(hao)(hao)約(yue)10%.這相當于令(ling)人驚(jing)愕的(de)(de)129太瓦時(shi)(shi)（即為1,290億千(qian)瓦時(shi)(shi)）的(de)(de)電能(neng)，或者(zhe)是(shi)(shi)36座(zuo)400兆(zhao)瓦發電廠輸出(chu)的(de)(de)電能(neng)，導致每年排放(fang)7,500萬噸二(er)氧化碳(tan)。

　　在(zai)美國(guo)(guo)，2008年7月1日生效的(de)(de)(de)(de)現行聯邦標(biao)(biao)準要求功(gong)(gong)(gong)率(lv)低于(yu)(yu)250 W的(de)(de)(de)(de)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)空(kong)載能(neng)耗(hao)低于(yu)(yu)500 mW.最近，美國(guo)(guo)能(neng)源(yuan)(yuan)(yuan)部（DOE）提(ti)出(chu)(chu)了更嚴格的(de)(de)(de)(de)電(dian)(dian)(dian)池充電(dian)(dian)(dian)器及(ji)電(dian)(dian)(dian)子(zi)產(chan)品電(dian)(dian)(dian)源(yuan)(yuan)(yuan)能(neng)效標(biao)(biao)準，并將于(yu)(yu)2013年7月1日生效。根(gen)據(ju)新標(biao)(biao)準，銘(ming)牌(pai)輸出(chu)(chu)功(gong)(gong)(gong)率(lv)介于(yu)(yu)49至250 W之間（典型筆記本(ben)視頻器功(gong)(gong)(gong)率(lv)位于(yu)(yu)此范(fan)圍）的(de)(de)(de)(de)交流-直流（AC-DC）外部電(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)(de)(de)最大(da)空(kong)載能(neng)耗(hao)必須(xu)低于(yu)(yu)0.210 W.然而，這些國(guo)(guo)家標(biao)(biao)準通常(chang)(chang)落(luo)后于(yu)(yu)其它標(biao)(biao)準及(ji)市(shi)場要求。美國(guo)(guo)1975年能(neng)源(yuan)(yuan)(yuan)政策及(ji)節(jie)能(neng)法(fa)案(an)（EPCA）規定(ding)：任何新的(de)(de)(de)(de)節(jie)能(neng)標(biao)(biao)準的(de)(de)(de)(de)制(zhi)定(ding)必須(xu)旨在(zai)提(ti)供最大(da)程度(du)的(de)(de)(de)(de)能(neng)效提(ti)升，不(bu)(bu)僅要在(zai)技術(shu)上可行，也要具(ju)備經濟合理(li)性。因此，這些國(guo)(guo)家標(biao)(biao)準通常(chang)(chang)并不(bu)(bu)代表“一流的(de)(de)(de)(de)”性能(neng)。諸多電(dian)(dian)(dian)源(yuan)(yuan)(yuan)制(zhi)造商要求將空(kong)載能(neng)耗(hao)限制(zhi)到盡可能(neng)地低，從而將其產(chan)品與競爭產(chan)品區別開來。

　　圖1:美國(guo)能源部(bu)提出的AC-DC外部(bu)電源節(jie)能標準

　　在(zai)能(neng)效(xiao)標(biao)準(zhun)上最為(wei)進取的政府(fu)機(ji)構很可能(neng)是美(mei)國(guo)加(jia)(jia)州(zhou)(zhou)(zhou)。電(dian)(dian)(dian)(dian)源制(zhi)造商(shang)可不想提(ti)供(gong)僅針對加(jia)(jia)州(zhou)(zhou)(zhou)的特(te)定型號(hao)產品(pin)，因此，加(jia)(jia)州(zhou)(zhou)(zhou)標(biao)準(zhun)的實(shi)際影響范(fan)圍要廣得多。例如，美(mei)國(guo)加(jia)(jia)州(zhou)(zhou)(zhou)在(zai)2012年1月(yue)出(chu)臺(tai)的新的電(dian)(dian)(dian)(dian)器(qi)能(neng)效(xiao)規范(fan)將(jiang)電(dian)(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)系統作為(wei)重要焦點。加(jia)(jia)州(zhou)(zhou)(zhou)每年有超過1.7億(yi)個(ge)(ge)充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)被用(yong)于充(chong)(chong)電(dian)(dian)(dian)(dian)，根(gen)據(ju)推測，在(zai)此特(te)別領域提(ti)升(sheng)能(neng)效(xiao)，每年將(jiang)可節省(sheng)2,200吉瓦時(shi)(shi)（即(ji)22億(yi)千瓦時(shi)(shi)）的電(dian)(dian)(dian)(dian)能(neng)。這(zhe)些電(dian)(dian)(dian)(dian)路足(zu)夠為(wei)35萬個(ge)(ge)家(jia)庭供(gong)電(dian)(dian)(dian)(dian)，相當于為(wei)住宅(zhai)/商(shang)業用(yong)電(dian)(dian)(dian)(dian)賬單每年節省(sheng)3.06億(yi)美(mei)元。美(mei)國(guo)加(jia)(jia)州(zhou)(zhou)(zhou)能(neng)源委員會（CEC）實(shi)施的這(zhe)些能(neng)效(xiao)規范(fan)要求手機(ji)、個(ge)(ge)人照護設(she)備(bei)及(ji)電(dian)(dian)(dian)(dian)動工具(ju)所使(shi)用(yong)的所有消(xiao)費類充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)在(zai)2013年2月(yue)前(qian)必須遵(zun)從(cong)，而工業類充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)須在(zai)未來12個(ge)(ge)月(yue)內遵(zun)從(cong)。美(mei)國(guo)其(qi)他幾個(ge)(ge)州(zhou)(zhou)(zhou)希(xi)望遵(zun)循(xun)加(jia)(jia)州(zhou)(zhou)(zhou)降低待機(ji)能(neng)耗限制(zhi)值的范(fan)例。

　　圖2:電動工具(ju)所用的典型老式充(chong)電系(xi)統

　　圖2介紹了過(guo)去常用的(de)基本充(chong)電(dian)器(qi)系(xi)統電(dian)路圖。此(ci)特別(bie)案例使用鎳鉻（NiCd）電(dian)池(chi)來為(wei)電(dian)動(dong)工具充(chong)電(dian)。電(dian)池(chi)在1小(xiao)時內的(de)電(dian)量(liang)(liang)標為(wei)C.例如，以0.5 C的(de)充(chong)電(dian)速率來為(wei)額定容量(liang)(liang)600 mAh的(de)電(dian)池(chi)充(chong)電(dian)，使用300 mA充(chong)電(dian)電(dian)流要經歷超過(guo)2小(xiao)時才能完全(quan)充(chong)滿電(dian)池(chi)。

　　圖(tu)2中的(de)(de)(de)電(dian)路(lu)(lu)能(neng)以0.1 C的(de)(de)(de)恒定充(chong)(chong)電(dian)速率(lv)。由于充(chong)(chong)電(dian)器的(de)(de)(de)60 Hz變壓器的(de)(de)(de)設計(ji)意圖(tu)是維持(chi)低(di)成本，而(er)非(fei)提供高(gao)能(neng)效等級，空載能(neng)耗(hao)通常將高(gao)于0.5 W,如此高(gao)的(de)(de)(de)空載能(neng)耗(hao)不再能(neng)夠(gou)令人接受。早(zao)期想法是使充(chong)(chong)電(dian)器能(neng)效更高(gao)，但不注意事實上(shang)充(chong)(chong)電(dian)后(hou)電(dian)路(lu)(lu)會持(chi)續無限期地(di)浪(lang)費電(dian)能(neng)。這已經被證明(ming)是一種有點誤導的(de)(de)(de)視角(jiao)。

　　即便是當今市(shi)場上的許(xu)多充(chong)電(dian)器，也(ye)仍(reng)然缺乏檢測電(dian)池是否完(wan)全充(chong)滿的能力，且因此在充(chong)電(dian)過(guo)程完(wan)成后仍(reng)然持(chi)續提供電(dian)能給電(dian)池，因而浪費電(dian)能（釋放為(wei)熱量）。通(tong)過(guo)使用可(ke)以(yi)關(guan)閉完(wan)全充(chong)滿之電(dian)池的充(chong)電(dian)通(tong)道，電(dian)能就不(bu)會無謂地浪費，電(dian)池也(ye)不(bu)會置于損壞的風(feng)險(xian)。

    提(ti)供低待機(ji)能耗工(gong)作的創新方案

　　家庭中一(yi)(yi)項常見(jian)的(de)待機能耗(hao)源頭就是筆(bi)(bi)記本(ben)適(shi)配(pei)器(qi)(qi)。這些適(shi)配(pei)器(qi)(qi)相當多的(de)使用時間(jian)是在筆(bi)(bi)記本(ben)電(dian)(dian)腦斷開(kai)(kai)(kai)連接或(huo)關(guan)斷的(de)情況(kuang)下在桌(zhuo)子底下度過的(de)。如今典型的(de)市售筆(bi)(bi)記本(ben)適(shi)配(pei)器(qi)(qi)在空載(zai)(zai)條件下約消耗(hao)300 mW至500 mW的(de)能耗(hao)。然(ran)而，許多領先制(zhi)(zhi)造商如今要求下一(yi)(yi)代筆(bi)(bi)記本(ben)適(shi)配(pei)器(qi)(qi)的(de)空載(zai)(zai)能耗(hao)限制(zhi)(zhi)到(dao)低于30 mW,從而使其產品與競(jing)爭產品區域開(kai)(kai)(kai)來。圖3顯示(shi)了65 W筆(bi)(bi)記本(ben)適(shi)配(pei)器(qi)(qi)用下一(yi)(yi)代充電(dian)(dian)系統的(de)簡化(hua)示(shi)例。此(ci)電(dian)(dian)路最重要的(de)元器(qi)(qi)件就是固定(ding)頻率電(dian)(dian)流模(mo)式控制(zhi)(zhi)器(qi)(qi)IC及次級端開(kai)(kai)(kai)關(guan)電(dian)(dian)源（SMPS）控制(zhi)(zhi)器(qi)(qi)IC.

　　圖3:帶空載檢測(ce)功能的先進(jin)充電(dian)電(dian)路(lu)簡化電(dian)路(lu)圖

　　這(zhe)示例中(zhong)指定(ding)的(de)(de)(de)(de)固定(ding)頻率電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)模式(shi)控制器(qi)（即安森美半導體的(de)(de)(de)(de)NCP1246）經過了專門優化，在空(kong)載(zai)及(ji)輕載(zai)條件下(xia)消(xiao)耗(hao)(hao)(hao)(hao)極低的(de)(de)(de)(de)能(neng)耗(hao)(hao)(hao)(hao)。交(jiao)流(liu)(liu)(liu)-直流(liu)(liu)(liu)（AC-DC）電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)空(kong)載(zai)條件下(xia)輸入能(neng)耗(hao)(hao)(hao)(hao)的(de)(de)(de)(de)其中(zhong)一(yi)(yi)項(xiang)主要來源(yuan)是X2電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路。典型適配器(qi)包含高壓X2電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容，它(ta)連(lian)接至交(jiao)流(liu)(liu)(liu)輸入端，作為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁干(gan)擾(rao)（EMI）濾波器(qi)的(de)(de)(de)(de)一(yi)(yi)部分。出于(yu)安全原(yuan)因，強(qiang)制要求此(ci)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容在從(cong)墻上拔出適配器(qi)插(cha)頭(tou)(tou)后的(de)(de)(de)(de)1秒時間內放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)至安全電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平。否(fou)則，接觸(chu)交(jiao)流(liu)(liu)(liu)插(cha)頭(tou)(tou)的(de)(de)(de)(de)扁腳（prong）就面(mian)臨電(dian)(dian)(dian)(dian)(dian)(dian)(dian)擊(ji)的(de)(de)(de)(de)危險(xian)。符(fu)合此(ci)要求的(de)(de)(de)(de)標準(zhun)方法是使用一(yi)(yi)串與電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容并(bing)聯的(de)(de)(de)(de)高阻(zu)抗泄放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)。當(dang)用于(yu)230 Vac應用時，這(zhe)恒(heng)(heng)定(ding)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)型消(xiao)耗(hao)(hao)(hao)(hao)源(yuan)約消(xiao)耗(hao)(hao)(hao)(hao)25 mW輸入能(neng)耗(hao)(hao)(hao)(hao)。當(dang)顧及(ji)到空(kong)載(zai)能(neng)耗(hao)(hao)(hao)(hao)時，這(zhe)25 mW就變得相(xiang)當(dang)大了。NCP1246解決(jue)此(ci)問題(ti)的(de)(de)(de)(de)方法是加入帶有源(yuan)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)內置交(jiao)流(liu)(liu)(liu)線路檢測器(qi)。這(zhe)控制器(qi)在檢測到不再(zai)存在交(jiao)流(liu)(liu)(liu)信號(hao)時，激活內置開關來使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。有了這(zhe)個功能(neng)，就不再(zai)需(xu)要泄放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)了，消(xiao)除了恒(heng)(heng)定(ding)的(de)(de)(de)(de)25 mW能(neng)耗(hao)(hao)(hao)(hao)源(yuan)頭(tou)(tou)。

　　次級(ji)端(duan)(duan)(duan)開關(guan)電(dian)(dian)源控(kong)(kong)制器(qi)（即安森美半導體(ti)的(de)NCP4354）是NCP1246的(de)伴侶(lv)IC,能(neng)(neng)夠檢測(ce)空載(zai)條(tiao)件，并使電(dian)(dian)源進入低(di)能(neng)(neng)耗關(guan)閉(bi)(bi)模式(shi)(shi)。在(zai)關(guan)閉(bi)(bi)模式(shi)(shi)期間，初(chu)級(ji)端(duan)(duan)(duan)控(kong)(kong)制器(qi)停(ting)止工(gong)作(zuo)，能(neng)(neng)量由輸(shu)(shu)(shu)出(chu)電(dian)(dian)容(rong)提(ti)(ti)供(gong)。適配器(qi)的(de)輸(shu)(shu)(shu)出(chu)電(dian)(dian)壓(ya)開始(shi)下降，因為初(chu)級(ji)端(duan)(duan)(duan)不(bu)再在(zai)存(cun)在(zai)開關(guan)工(gong)作(zuo)。這并不(bu)構成什么(me)問題(ti)，因為適配器(qi)在(zai)此模式(shi)(shi)下不(bu)再連接至筆記本電(dian)(dian)腦。輸(shu)(shu)(shu)出(chu)電(dian)(dian)壓(ya)被允許下降至某個(ge)可調節電(dian)(dian)平，直到(dao)NCP4354通(tong)知初(chu)級(ji)端(duan)(duan)(duan)重啟，重新為輸(shu)(shu)(shu)出(chu)電(dian)(dian)容(rong)充(chong)電(dian)(dian)并因此維持工(gong)作(zuo)。當適配器(qi)重新連接至電(dian)(dian)池時，NCP4354控(kong)(kong)制器(qi)自動重啟初(chu)級(ji)端(duan)(duan)(duan)控(kong)(kong)制器(qi)。能(neng)(neng)僅(jin)以一(yi)顆光(guang)耦提(ti)(ti)供(gong)反饋控(kong)(kong)制及導通(tong)/關(guan)閉(bi)(bi)信號。當在(zai)此類電(dian)(dian)路中一(yi)起(qi)使用時，NCP1246和NCP4354能(neng)(neng)夠采用美國規格的(de)交流(liu)主電(dian)(dian)源提(ti)(ti)供(gong)低(di)于10 mW的(de)空載(zai)能(neng)(neng)耗，且在(zai)寬交流(liu)主電(dian)(dian)源電(dian)(dian)壓(ya)范圍下提(ti)(ti)供(gong)低(di)于20 mW的(de)空載(zai)能(neng)(neng)耗。

　　圖(tu)4:65 W適配器電路圖(tu)

　　雖然許多消(xiao)費電子OEM生(sheng)產(chan)高能(neng)效產(chan)品，但他們常常會(hui)對低能(neng)耗(hao)的充電系(xi)統感到失望。如今(jin)已經出現重要進展，電池充電器可(ke)以消(xiao)耗(hao)更(geng)少電能(neng)，同時提供市場所要求的高性能(neng)基準(zhun)。諸如本(ben)(ben)文所介紹的系(xi)統致力于滿足這些標準(zhun)，并降低系(xi)統復(fu)雜度(du)、節省珍貴(gui)的電路板空間及(ji)使物料單（BOM）成(cheng)本(ben)(ben)受到控制。