從為(wei)平板(ban)電腦或(huo)智能手機電池充電到為(wei)膝上型電腦或(huo)家用路由(you)器(qi)(qi)供(gong)電，電源適(shi)配(pei)器(qi)(qi)長期(qi)以來都(dou)是人們日常(chang)(chang)生活的(de)(de)必要組成(cheng)部(bu)分。對于將(jiang)電源適(shi)配(pei)器(qi)(qi)與其產品搭(da)配(pei)到一起的(de)(de)消費電子原設(she)備制造商（OEM）而(er)言，需(xu)要因應(ying)兩項(xiang)關鍵推動(dong)(dong)因素(su)，即(ji)確(que)保提供(gong)高能效等級(ji)并滿足安全規范(fan)，同(tong)時(shi)還需(xu)提供(gong)緊湊的(de)(de)外形因數。近(jin)年來，由(you)于結合了(le)政府(fu)法規及美國(guo)(guo)“能源之(zhi)星”、歐盟生態設(she)計指(zhi)令(ling)及中國(guo)(guo)標(biao)準化(hua)研究(jiu)院（CNIS）等能效項(xiang)目(mu)，業界非常(chang)(chang)注重通(tong)過減(jian)小待機模式下的(de)(de)使(shi)用的(de)(de)電能來降(jiang)低適(shi)配(pei)器(qi)(qi)的(de)(de)總體能耗等級(ji)。本文將(jiang)探討推動(dong)(dong)最(zui)新要求的(de)(de)新興技術趨勢(shi)，包括要求減(jian)少使(shi)用的(de)(de)外部(bu)元器(qi)(qi)件數量、使(shi)設(she)計更時(shi)髦輕薄的(de)(de)工藝(yi)。

　　待機能(neng)耗(hao)有時(shi)候也稱作“吸(xi)血鬼(gui)能(neng)耗(hao)”或是“虛負(fu)載(zai)”,指(zhi)的是電(dian)子設備及電(dian)器在關斷電(dian)源但仍然插在電(dian)源插座上時(shi)消耗(hao)的電(dian)能(neng)。以美國為(wei)例，待機能(neng)耗(hao)約(yue)占美國家庭平(ping)均總能(neng)耗(hao)約(yue)10%.這相當于令(ling)人驚愕的129太瓦時(shi)（即為(wei)1,290億千瓦時(shi)）的電(dian)能(neng)，或者是36座400兆瓦發電(dian)廠輸出(chu)的電(dian)能(neng)，導致每(mei)年排放7,500萬(wan)噸二(er)氧化碳。

　　在美國(guo)(guo)，2008年7月1日生效的(de)現(xian)行聯邦標準要求(qiu)(qiu)功(gong)率低(di)(di)于(yu)(yu)250 W的(de)電源(yuan)空(kong)載(zai)能(neng)(neng)耗(hao)(hao)低(di)(di)于(yu)(yu)500 mW.最(zui)(zui)近，美國(guo)(guo)能(neng)(neng)源(yuan)部（DOE）提(ti)出了(le)更嚴格的(de)電池充電器(qi)及電子產品電源(yuan)能(neng)(neng)效標準，并將于(yu)(yu)2013年7月1日生效。根據新標準，銘牌輸出功(gong)率介于(yu)(yu)49至250 W之(zhi)間(jian)（典型筆記本視頻器(qi)功(gong)率位于(yu)(yu)此(ci)范圍）的(de)交(jiao)流(liu)-直流(liu)（AC-DC）外部電源(yuan)的(de)最(zui)(zui)大空(kong)載(zai)能(neng)(neng)耗(hao)(hao)必須低(di)(di)于(yu)(yu)0.210 W.然而，這些(xie)國(guo)(guo)家(jia)標準通(tong)(tong)常落后于(yu)(yu)其它標準及市場要求(qiu)(qiu)。美國(guo)(guo)1975年能(neng)(neng)源(yuan)政策及節能(neng)(neng)法案（EPCA）規定(ding)(ding)：任(ren)何新的(de)節能(neng)(neng)標準的(de)制(zhi)(zhi)定(ding)(ding)必須旨(zhi)在提(ti)供(gong)最(zui)(zui)大程度的(de)能(neng)(neng)效提(ti)升，不(bu)僅要在技術上可(ke)行，也要具(ju)備經濟合(he)理性。因此(ci)，這些(xie)國(guo)(guo)家(jia)標準通(tong)(tong)常并不(bu)代表“一(yi)流(liu)的(de)”性能(neng)(neng)。諸多電源(yuan)制(zhi)(zhi)造商要求(qiu)(qiu)將空(kong)載(zai)能(neng)(neng)耗(hao)(hao)限制(zhi)(zhi)到盡可(ke)能(neng)(neng)地低(di)(di)，從而將其產品與競(jing)爭(zheng)產品區別開來。

　　圖1:美國能(neng)源部提出的AC-DC外部電(dian)源節能(neng)標準

　　在(zai)能(neng)(neng)效(xiao)標準上最(zui)為進取的(de)政府(fu)機構很可能(neng)(neng)是美(mei)(mei)國(guo)(guo)加(jia)(jia)州(zhou)(zhou)。電(dian)(dian)源(yuan)制造商(shang)可不想提供(gong)僅針(zhen)對加(jia)(jia)州(zhou)(zhou)的(de)特(te)定型(xing)號產品(pin)，因(yin)此，加(jia)(jia)州(zhou)(zhou)標準的(de)實際影響范圍要(yao)(yao)廣得多。例如，美(mei)(mei)國(guo)(guo)加(jia)(jia)州(zhou)(zhou)在(zai)2012年(nian)1月出臺的(de)新的(de)電(dian)(dian)器(qi)能(neng)(neng)效(xiao)規范將(jiang)電(dian)(dian)池充(chong)電(dian)(dian)器(qi)系(xi)統作(zuo)為重要(yao)(yao)焦(jiao)點。加(jia)(jia)州(zhou)(zhou)每年(nian)有超(chao)過1.7億(yi)個充(chong)電(dian)(dian)器(qi)被用于充(chong)電(dian)(dian)，根據推測，在(zai)此特(te)別領域提升能(neng)(neng)效(xiao)，每年(nian)將(jiang)可節(jie)省(sheng)2,200吉瓦(wa)時（即22億(yi)千(qian)瓦(wa)時）的(de)電(dian)(dian)能(neng)(neng)。這(zhe)(zhe)些電(dian)(dian)路(lu)足夠為35萬個家庭供(gong)電(dian)(dian)，相當于為住宅(zhai)/商(shang)業(ye)用電(dian)(dian)賬單每年(nian)節(jie)省(sheng)3.06億(yi)美(mei)(mei)元。美(mei)(mei)國(guo)(guo)加(jia)(jia)州(zhou)(zhou)能(neng)(neng)源(yuan)委員會（CEC）實施(shi)的(de)這(zhe)(zhe)些能(neng)(neng)效(xiao)規范要(yao)(yao)求手(shou)機、個人照護設備及電(dian)(dian)動(dong)工具所使用的(de)所有消費(fei)類充(chong)電(dian)(dian)器(qi)在(zai)2013年(nian)2月前必須遵(zun)從，而工業(ye)類充(chong)電(dian)(dian)器(qi)須在(zai)未來12個月內遵(zun)從。美(mei)(mei)國(guo)(guo)其他幾個州(zhou)(zhou)希望(wang)遵(zun)循加(jia)(jia)州(zhou)(zhou)降低(di)待(dai)機能(neng)(neng)耗限制值(zhi)的(de)范例。

　　圖2:電動工具所用的典型老式充電系統

　　圖(tu)(tu)2介紹了(le)過去常用(yong)的基本充(chong)電(dian)(dian)器系統電(dian)(dian)路(lu)圖(tu)(tu)。此特別(bie)案例使(shi)用(yong)鎳鉻（NiCd）電(dian)(dian)池(chi)來為電(dian)(dian)動工具充(chong)電(dian)(dian)。電(dian)(dian)池(chi)在1小時內的電(dian)(dian)量標為C.例如，以0.5 C的充(chong)電(dian)(dian)速(su)率(lv)來為額定容(rong)量600 mAh的電(dian)(dian)池(chi)充(chong)電(dian)(dian)，使(shi)用(yong)300 mA充(chong)電(dian)(dian)電(dian)(dian)流要經歷超過2小時才能(neng)完全(quan)充(chong)滿電(dian)(dian)池(chi)。

　　圖(tu)(tu)2中的(de)電路(lu)(lu)能以0.1 C的(de)恒定充電速率。由于(yu)充電器的(de)60 Hz變壓器的(de)設計意圖(tu)(tu)是維持(chi)低成本(ben)，而非提供高(gao)能效等(deng)級，空(kong)(kong)載能耗通常(chang)將高(gao)于(yu)0.5 W,如此高(gao)的(de)空(kong)(kong)載能耗不再能夠令人接(jie)受。早(zao)期(qi)想法是使(shi)充電器能效更高(gao)，但(dan)不注意事實上(shang)充電后電路(lu)(lu)會持(chi)續(xu)無限期(qi)地浪費電能。這(zhe)已(yi)經被證明是一種有點誤(wu)導的(de)視角。

　　即(ji)便是當今市場(chang)上的(de)(de)許多(duo)充(chong)(chong)電(dian)(dian)(dian)器，也仍(reng)然缺(que)乏檢測電(dian)(dian)(dian)池是否完全充(chong)(chong)滿的(de)(de)能(neng)力，且因(yin)(yin)此在充(chong)(chong)電(dian)(dian)(dian)過程完成后仍(reng)然持(chi)續提供(gong)電(dian)(dian)(dian)能(neng)給電(dian)(dian)(dian)池，因(yin)(yin)而浪費電(dian)(dian)(dian)能(neng)（釋(shi)放為熱(re)量）。通(tong)過使用可以關閉完全充(chong)(chong)滿之電(dian)(dian)(dian)池的(de)(de)充(chong)(chong)電(dian)(dian)(dian)通(tong)道，電(dian)(dian)(dian)能(neng)就不會無謂地浪費，電(dian)(dian)(dian)池也不會置于(yu)損壞的(de)(de)風險。

    提供低待(dai)機(ji)能耗工作的創新方(fang)案

　　家庭中一(yi)項常見的(de)待機能耗源頭就是筆(bi)(bi)記本適(shi)(shi)配(pei)器(qi)。這(zhe)些適(shi)(shi)配(pei)器(qi)相當多的(de)使用時間(jian)是在筆(bi)(bi)記本電腦斷開(kai)連接或關斷的(de)情況下(xia)在桌子底下(xia)度過(guo)的(de)。如今典型的(de)市售筆(bi)(bi)記本適(shi)(shi)配(pei)器(qi)在空載條件(jian)下(xia)約消耗300 mW至500 mW的(de)能耗。然而(er)，許多領(ling)先(xian)制(zhi)(zhi)造商如今要求下(xia)一(yi)代筆(bi)(bi)記本適(shi)(shi)配(pei)器(qi)的(de)空載能耗限(xian)制(zhi)(zhi)到低于30 mW,從而(er)使其產品與競(jing)爭產品區域開(kai)來。圖3顯示(shi)了65 W筆(bi)(bi)記本適(shi)(shi)配(pei)器(qi)用下(xia)一(yi)代充(chong)電系統(tong)的(de)簡化(hua)示(shi)例。此電路(lu)最重要的(de)元器(qi)件(jian)就是固定頻率電流(liu)模式控(kong)制(zhi)(zhi)器(qi)IC及次級端(duan)開(kai)關電源（SMPS）控(kong)制(zhi)(zhi)器(qi)IC.

　　圖3:帶(dai)空載檢(jian)測功能的先進充(chong)電(dian)電(dian)路(lu)簡(jian)化電(dian)路(lu)圖

　　這(zhe)(zhe)示(shi)例中指定的(de)(de)(de)固定頻(pin)率電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)模式控(kong)制(zhi)器(qi)(qi)（即(ji)安森美半導體的(de)(de)(de)NCP1246）經過(guo)了(le)(le)(le)(le)專門優(you)化，在(zai)空載及輕載條件下消(xiao)耗(hao)極低的(de)(de)(de)能耗(hao)。交流(liu)-直流(liu)（AC-DC）電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)空載條件下輸入能耗(hao)的(de)(de)(de)其中一(yi)項主(zhu)要(yao)來源(yuan)是X2電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)路。典型適配器(qi)(qi)包(bao)含高壓X2電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)，它連接(jie)至交流(liu)輸入端，作為電(dian)(dian)(dian)(dian)(dian)(dian)磁干(gan)擾（EMI）濾波器(qi)(qi)的(de)(de)(de)一(yi)部分。出于安全(quan)原因，強制(zhi)要(yao)求(qiu)此(ci)(ci)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)在(zai)從(cong)墻(qiang)上拔出適配器(qi)(qi)插頭(tou)后的(de)(de)(de)1秒時(shi)間(jian)內放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)至安全(quan)電(dian)(dian)(dian)(dian)(dian)(dian)壓電(dian)(dian)(dian)(dian)(dian)(dian)平。否則，接(jie)觸交流(liu)插頭(tou)的(de)(de)(de)扁腳（prong）就(jiu)(jiu)面臨電(dian)(dian)(dian)(dian)(dian)(dian)擊(ji)的(de)(de)(de)危(wei)險。符合此(ci)(ci)要(yao)求(qiu)的(de)(de)(de)標準(zhun)方(fang)法是使用一(yi)串與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)并聯的(de)(de)(de)高阻抗泄放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)阻。當用于230 Vac應(ying)用時(shi)，這(zhe)(zhe)恒(heng)定的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)阻型消(xiao)耗(hao)源(yuan)約(yue)消(xiao)耗(hao)25 mW輸入能耗(hao)。當顧及到空載能耗(hao)時(shi)，這(zhe)(zhe)25 mW就(jiu)(jiu)變得相(xiang)當大了(le)(le)(le)(le)。NCP1246解決此(ci)(ci)問題的(de)(de)(de)方(fang)法是加入帶(dai)有源(yuan)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)內置交流(liu)線路檢(jian)測(ce)器(qi)(qi)。這(zhe)(zhe)控(kong)制(zhi)器(qi)(qi)在(zai)檢(jian)測(ce)到不再存在(zai)交流(liu)信(xin)號時(shi)，激活(huo)內置開關來使電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)。有了(le)(le)(le)(le)這(zhe)(zhe)個(ge)功能，就(jiu)(jiu)不再需要(yao)泄放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)阻了(le)(le)(le)(le)，消(xiao)除(chu)了(le)(le)(le)(le)恒(heng)定的(de)(de)(de)25 mW能耗(hao)源(yuan)頭(tou)。

　　次級(ji)端(duan)開(kai)關(guan)電(dian)(dian)(dian)(dian)源(yuan)控(kong)制(zhi)(zhi)(zhi)器(qi)(qi)（即安(an)森美(mei)(mei)半導(dao)(dao)體的(de)(de)(de)(de)NCP4354）是NCP1246的(de)(de)(de)(de)伴侶(lv)IC,能(neng)(neng)夠檢測(ce)空(kong)(kong)載條件，并使電(dian)(dian)(dian)(dian)源(yuan)進(jin)入低能(neng)(neng)耗(hao)關(guan)閉模(mo)式(shi)。在(zai)(zai)(zai)關(guan)閉模(mo)式(shi)期間(jian)，初(chu)(chu)級(ji)端(duan)控(kong)制(zhi)(zhi)(zhi)器(qi)(qi)停止工作(zuo)，能(neng)(neng)量(liang)由輸(shu)(shu)出電(dian)(dian)(dian)(dian)容提(ti)供(gong)(gong)。適配器(qi)(qi)的(de)(de)(de)(de)輸(shu)(shu)出電(dian)(dian)(dian)(dian)壓開(kai)始(shi)下(xia)降(jiang)，因為初(chu)(chu)級(ji)端(duan)不再在(zai)(zai)(zai)存在(zai)(zai)(zai)開(kai)關(guan)工作(zuo)。這并不構成什么問(wen)題(ti)，因為適配器(qi)(qi)在(zai)(zai)(zai)此(ci)(ci)模(mo)式(shi)下(xia)不再連(lian)(lian)接至(zhi)筆記本電(dian)(dian)(dian)(dian)腦。輸(shu)(shu)出電(dian)(dian)(dian)(dian)壓被(bei)允許下(xia)降(jiang)至(zhi)某個(ge)可調節電(dian)(dian)(dian)(dian)平，直到NCP4354通知初(chu)(chu)級(ji)端(duan)重(zhong)啟(qi)(qi)，重(zhong)新為輸(shu)(shu)出電(dian)(dian)(dian)(dian)容充電(dian)(dian)(dian)(dian)并因此(ci)(ci)維(wei)持工作(zuo)。當適配器(qi)(qi)重(zhong)新連(lian)(lian)接至(zhi)電(dian)(dian)(dian)(dian)池時，NCP4354控(kong)制(zhi)(zhi)(zhi)器(qi)(qi)自動重(zhong)啟(qi)(qi)初(chu)(chu)級(ji)端(duan)控(kong)制(zhi)(zhi)(zhi)器(qi)(qi)。能(neng)(neng)僅以(yi)一(yi)顆光耦提(ti)供(gong)(gong)反饋控(kong)制(zhi)(zhi)(zhi)及導(dao)(dao)通/關(guan)閉信號。當在(zai)(zai)(zai)此(ci)(ci)類電(dian)(dian)(dian)(dian)路中(zhong)一(yi)起使用(yong)(yong)時，NCP1246和NCP4354能(neng)(neng)夠采(cai)用(yong)(yong)美(mei)(mei)國規(gui)格的(de)(de)(de)(de)交(jiao)流(liu)主電(dian)(dian)(dian)(dian)源(yuan)提(ti)供(gong)(gong)低于(yu)(yu)10 mW的(de)(de)(de)(de)空(kong)(kong)載能(neng)(neng)耗(hao)，且在(zai)(zai)(zai)寬交(jiao)流(liu)主電(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)壓范(fan)圍下(xia)提(ti)供(gong)(gong)低于(yu)(yu)20 mW的(de)(de)(de)(de)空(kong)(kong)載能(neng)(neng)耗(hao)。

　　圖4:65 W適配器電(dian)路圖

　　雖然許多消費電(dian)(dian)子OEM生(sheng)產高能效產品，但他(ta)們常(chang)常(chang)會對(dui)低能耗(hao)的充電(dian)(dian)系統感到失望。如今已經出(chu)現重要進(jin)展(zhan)，電(dian)(dian)池充電(dian)(dian)器可以消耗(hao)更少電(dian)(dian)能，同時提(ti)供市場所(suo)要求的高性能基準(zhun)。諸如本文所(suo)介紹的系統致力于滿(man)足這些(xie)標準(zhun)，并降低系統復雜度、節省珍(zhen)貴的電(dian)(dian)路板空間及使物料(liao)單（BOM）成本受到控制。