從(cong)為(wei)平板電(dian)(dian)(dian)腦或智(zhi)能(neng)手機電(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)到為(wei)膝上型電(dian)(dian)(dian)腦或家用(yong)(yong)路由器(qi)供(gong)電(dian)(dian)(dian)，電(dian)(dian)(dian)源適(shi)配(pei)(pei)器(qi)長期以來(lai)都是人們日(ri)常生(sheng)活的(de)(de)必要組成部分。對于將(jiang)電(dian)(dian)(dian)源適(shi)配(pei)(pei)器(qi)與其產品搭配(pei)(pei)到一起的(de)(de)消費電(dian)(dian)(dian)子(zi)原(yuan)設(she)備制造商(shang)（OEM）而(er)言，需要因(yin)(yin)應兩(liang)項(xiang)關鍵推(tui)動(dong)因(yin)(yin)素(su)，即確保提(ti)供(gong)高能(neng)效(xiao)等級并滿足安全規(gui)范，同(tong)時還(huan)需提(ti)供(gong)緊湊的(de)(de)外形因(yin)(yin)數。近年來(lai)，由于結(jie)合了政府(fu)法(fa)規(gui)及美國(guo)“能(neng)源之星”、歐盟生(sheng)態設(she)計指令(ling)及中國(guo)標(biao)準化研究院（CNIS）等能(neng)效(xiao)項(xiang)目(mu)，業界非常注重通過減小(xiao)待(dai)機模式下的(de)(de)使(shi)用(yong)(yong)的(de)(de)電(dian)(dian)(dian)能(neng)來(lai)降低(di)適(shi)配(pei)(pei)器(qi)的(de)(de)總體能(neng)耗等級。本(ben)文將(jiang)探討推(tui)動(dong)最新(xin)要求的(de)(de)新(xin)興技(ji)術趨勢，包括要求減少使(shi)用(yong)(yong)的(de)(de)外部元器(qi)件數量、使(shi)設(she)計更時髦輕薄的(de)(de)工藝(yi)。

　　待機能(neng)(neng)耗有(you)時候也(ye)稱(cheng)作“吸血鬼能(neng)(neng)耗”或是(shi)“虛負載”,指的(de)是(shi)電(dian)(dian)子(zi)設備及(ji)電(dian)(dian)器在關斷(duan)電(dian)(dian)源(yuan)但仍然插(cha)在電(dian)(dian)源(yuan)插(cha)座(zuo)上時消(xiao)耗的(de)電(dian)(dian)能(neng)(neng)。以美(mei)國為例(li)，待機能(neng)(neng)耗約占美(mei)國家(jia)庭平均總能(neng)(neng)耗約10%.這(zhe)相(xiang)當于令人(ren)驚愕的(de)129太瓦(wa)時（即為1,290億千瓦(wa)時）的(de)電(dian)(dian)能(neng)(neng)，或者是(shi)36座(zuo)400兆瓦(wa)發電(dian)(dian)廠輸出(chu)的(de)電(dian)(dian)能(neng)(neng)，導(dao)致每年排(pai)放7,500萬噸二氧(yang)化碳。

　　在(zai)美(mei)(mei)國(guo)，2008年(nian)7月1日(ri)生效的(de)現行聯邦標(biao)準(zhun)(zhun)要求功率(lv)低(di)于(yu)250 W的(de)電(dian)源空(kong)載(zai)能(neng)(neng)(neng)耗(hao)低(di)于(yu)500 mW.最(zui)近，美(mei)(mei)國(guo)能(neng)(neng)(neng)源部（DOE）提(ti)出了(le)更嚴格的(de)電(dian)池充(chong)電(dian)器(qi)及(ji)電(dian)子產品電(dian)源能(neng)(neng)(neng)效標(biao)準(zhun)(zhun)，并將(jiang)于(yu)2013年(nian)7月1日(ri)生效。根據新(xin)標(biao)準(zhun)(zhun)，銘牌輸出功率(lv)介于(yu)49至250 W之間（典型(xing)筆記本視頻器(qi)功率(lv)位于(yu)此范圍）的(de)交(jiao)流(liu)-直流(liu)（AC-DC）外(wai)部電(dian)源的(de)最(zui)大(da)空(kong)載(zai)能(neng)(neng)(neng)耗(hao)必須低(di)于(yu)0.210 W.然(ran)而，這(zhe)些國(guo)家標(biao)準(zhun)(zhun)通常落(luo)后于(yu)其(qi)它標(biao)準(zhun)(zhun)及(ji)市(shi)場要求。美(mei)(mei)國(guo)1975年(nian)能(neng)(neng)(neng)源政策及(ji)節(jie)能(neng)(neng)(neng)法案(an)（EPCA）規定：任(ren)何新(xin)的(de)節(jie)能(neng)(neng)(neng)標(biao)準(zhun)(zhun)的(de)制定必須旨在(zai)提(ti)供最(zui)大(da)程度(du)的(de)能(neng)(neng)(neng)效提(ti)升，不僅要在(zai)技術上可行，也要具(ju)備經濟(ji)合理性(xing)。因此，這(zhe)些國(guo)家標(biao)準(zhun)(zhun)通常并不代表(biao)“一流(liu)的(de)”性(xing)能(neng)(neng)(neng)。諸多(duo)電(dian)源制造商要求將(jiang)空(kong)載(zai)能(neng)(neng)(neng)耗(hao)限(xian)制到盡可能(neng)(neng)(neng)地(di)低(di)，從(cong)而將(jiang)其(qi)產品與競爭產品區別(bie)開來。

　　圖1:美國能源(yuan)部提出的(de)AC-DC外部電源(yuan)節能標準(zhun)

　　在能(neng)效(xiao)(xiao)標準(zhun)上最(zui)為(wei)(wei)進取(qu)的(de)政府(fu)機構很(hen)可(ke)能(neng)是美(mei)國(guo)(guo)加(jia)(jia)(jia)州(zhou)。電源(yuan)制(zhi)造商可(ke)不想提(ti)供(gong)僅針對加(jia)(jia)(jia)州(zhou)的(de)特定型號產(chan)品，因此，加(jia)(jia)(jia)州(zhou)標準(zhun)的(de)實(shi)際影響(xiang)范(fan)圍要(yao)廣(guang)得多。例如(ru)，美(mei)國(guo)(guo)加(jia)(jia)(jia)州(zhou)在2012年(nian)1月出(chu)臺的(de)新的(de)電器能(neng)效(xiao)(xiao)規(gui)范(fan)將電池充電器系統(tong)作為(wei)(wei)重(zhong)要(yao)焦點。加(jia)(jia)(jia)州(zhou)每(mei)年(nian)有超過1.7億個充電器被用(yong)于充電，根據推測(ce)，在此特別領域提(ti)升(sheng)能(neng)效(xiao)(xiao)，每(mei)年(nian)將可(ke)節省2,200吉瓦(wa)時(shi)（即22億千瓦(wa)時(shi)）的(de)電能(neng)。這些電路足夠為(wei)(wei)35萬(wan)個家庭供(gong)電，相當(dang)于為(wei)(wei)住宅(zhai)/商業用(yong)電賬單每(mei)年(nian)節省3.06億美(mei)元。美(mei)國(guo)(guo)加(jia)(jia)(jia)州(zhou)能(neng)源(yuan)委員會（CEC）實(shi)施的(de)這些能(neng)效(xiao)(xiao)規(gui)范(fan)要(yao)求(qiu)手機、個人照護設備(bei)及電動工具所使(shi)用(yong)的(de)所有消費類充電器在2013年(nian)2月前(qian)必(bi)須遵(zun)從，而工業類充電器須在未來12個月內遵(zun)從。美(mei)國(guo)(guo)其他幾(ji)個州(zhou)希望遵(zun)循加(jia)(jia)(jia)州(zhou)降低(di)待機能(neng)耗限制(zhi)值的(de)范(fan)例。

　　圖2:電動(dong)工具(ju)所用的典型老式充電系統

　　圖(tu)2介(jie)紹了(le)過(guo)去(qu)常用的(de)(de)基本(ben)充(chong)(chong)電(dian)(dian)器(qi)系統電(dian)(dian)路圖(tu)。此特別案例(li)使用鎳鉻（NiCd）電(dian)(dian)池(chi)(chi)來(lai)為電(dian)(dian)動工具充(chong)(chong)電(dian)(dian)。電(dian)(dian)池(chi)(chi)在1小時內的(de)(de)電(dian)(dian)量(liang)標為C.例(li)如，以0.5 C的(de)(de)充(chong)(chong)電(dian)(dian)速率來(lai)為額定容量(liang)600 mAh的(de)(de)電(dian)(dian)池(chi)(chi)充(chong)(chong)電(dian)(dian)，使用300 mA充(chong)(chong)電(dian)(dian)電(dian)(dian)流要經歷超過(guo)2小時才能(neng)完(wan)全(quan)充(chong)(chong)滿(man)電(dian)(dian)池(chi)(chi)。

　　圖2中的(de)電(dian)路能(neng)(neng)(neng)以0.1 C的(de)恒(heng)定充(chong)電(dian)速率。由于(yu)充(chong)電(dian)器的(de)60 Hz變壓器的(de)設(she)計(ji)意圖是維(wei)持低(di)成本，而(er)非提供高(gao)(gao)能(neng)(neng)(neng)效(xiao)等(deng)級(ji)，空(kong)載能(neng)(neng)(neng)耗通(tong)常將(jiang)高(gao)(gao)于(yu)0.5 W,如此高(gao)(gao)的(de)空(kong)載能(neng)(neng)(neng)耗不再(zai)能(neng)(neng)(neng)夠(gou)令(ling)人接受(shou)。早期想法是使充(chong)電(dian)器能(neng)(neng)(neng)效(xiao)更(geng)高(gao)(gao)，但不注意事實上(shang)充(chong)電(dian)后(hou)電(dian)路會持續(xu)無限(xian)期地(di)浪費電(dian)能(neng)(neng)(neng)。這已經被證明是一種有點誤(wu)導的(de)視(shi)角。

　　即(ji)便是(shi)當今市(shi)場上的(de)許多充電(dian)(dian)器，也仍(reng)然缺乏(fa)檢測電(dian)(dian)池是(shi)否完(wan)全充滿的(de)能力，且因此在充電(dian)(dian)過程完(wan)成(cheng)后仍(reng)然持續(xu)提(ti)供電(dian)(dian)能給電(dian)(dian)池，因而浪(lang)費(fei)電(dian)(dian)能（釋放(fang)為熱量）。通(tong)過使用可(ke)以關閉完(wan)全充滿之電(dian)(dian)池的(de)充電(dian)(dian)通(tong)道，電(dian)(dian)能就(jiu)不會無謂(wei)地浪(lang)費(fei)，電(dian)(dian)池也不會置于損壞的(de)風險。

    提供低待機能耗工作的(de)創新(xin)方案

　　家庭中一(yi)項常見的(de)待機能(neng)耗(hao)源(yuan)頭就(jiu)是筆記本(ben)適(shi)(shi)配器。這些適(shi)(shi)配器相當多(duo)的(de)使用時間是在(zai)筆記本(ben)電(dian)(dian)(dian)腦(nao)斷(duan)(duan)開(kai)連接或(huo)關(guan)斷(duan)(duan)的(de)情況(kuang)下(xia)在(zai)桌子底下(xia)度過(guo)的(de)。如(ru)今典型的(de)市售筆記本(ben)適(shi)(shi)配器在(zai)空(kong)載條件下(xia)約消(xiao)耗(hao)300 mW至(zhi)500 mW的(de)能(neng)耗(hao)。然而，許多(duo)領先制(zhi)(zhi)(zhi)造商(shang)如(ru)今要(yao)求下(xia)一(yi)代筆記本(ben)適(shi)(shi)配器的(de)空(kong)載能(neng)耗(hao)限制(zhi)(zhi)(zhi)到低于(yu)30 mW,從而使其產品(pin)與競爭產品(pin)區域開(kai)來(lai)。圖3顯示(shi)了65 W筆記本(ben)適(shi)(shi)配器用下(xia)一(yi)代充電(dian)(dian)(dian)系統的(de)簡(jian)化示(shi)例。此電(dian)(dian)(dian)路(lu)最重(zhong)要(yao)的(de)元器件就(jiu)是固(gu)定頻率電(dian)(dian)(dian)流模式控制(zhi)(zhi)(zhi)器IC及次級(ji)端開(kai)關(guan)電(dian)(dian)(dian)源(yuan)（SMPS）控制(zhi)(zhi)(zhi)器IC.

　　圖3:帶空(kong)載檢測功能的先進充電(dian)電(dian)路簡(jian)化電(dian)路圖

　　這(zhe)示例中指定(ding)(ding)的(de)(de)(de)固(gu)定(ding)(ding)頻率電(dian)(dian)(dian)(dian)(dian)流(liu)模式(shi)控(kong)制(zhi)器(qi)(qi)(qi)（即安森美半導(dao)體(ti)的(de)(de)(de)NCP1246）經過了(le)專(zhuan)門優化，在(zai)(zai)空(kong)(kong)載及輕載條件(jian)下(xia)消(xiao)(xiao)(xiao)耗(hao)極(ji)低的(de)(de)(de)能耗(hao)。交流(liu)-直流(liu)（AC-DC）電(dian)(dian)(dian)(dian)(dian)源(yuan)空(kong)(kong)載條件(jian)下(xia)輸入(ru)(ru)能耗(hao)的(de)(de)(de)其中一(yi)(yi)項主要(yao)來源(yuan)是(shi)(shi)X2電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)放(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路。典型適配器(qi)(qi)(qi)包(bao)含高壓(ya)X2電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)，它連接至(zhi)交流(liu)輸入(ru)(ru)端，作為(wei)電(dian)(dian)(dian)(dian)(dian)磁干(gan)擾（EMI）濾(lv)波器(qi)(qi)(qi)的(de)(de)(de)一(yi)(yi)部分。出于安全原(yuan)因，強制(zhi)要(yao)求此(ci)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)在(zai)(zai)從墻上拔出適配器(qi)(qi)(qi)插(cha)頭后的(de)(de)(de)1秒時間(jian)內放(fang)電(dian)(dian)(dian)(dian)(dian)至(zhi)安全電(dian)(dian)(dian)(dian)(dian)壓(ya)電(dian)(dian)(dian)(dian)(dian)平。否(fou)則，接觸(chu)交流(liu)插(cha)頭的(de)(de)(de)扁腳(jiao)（prong）就(jiu)面臨電(dian)(dian)(dian)(dian)(dian)擊的(de)(de)(de)危險。符合(he)此(ci)要(yao)求的(de)(de)(de)標(biao)準方法是(shi)(shi)使(shi)用(yong)一(yi)(yi)串與電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)并聯的(de)(de)(de)高阻(zu)(zu)抗(kang)泄(xie)放(fang)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)。當用(yong)于230 Vac應用(yong)時，這(zhe)恒定(ding)(ding)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)型消(xiao)(xiao)(xiao)耗(hao)源(yuan)約消(xiao)(xiao)(xiao)耗(hao)25 mW輸入(ru)(ru)能耗(hao)。當顧及到空(kong)(kong)載能耗(hao)時，這(zhe)25 mW就(jiu)變(bian)得相當大了(le)。NCP1246解(jie)決此(ci)問題的(de)(de)(de)方法是(shi)(shi)加入(ru)(ru)帶有源(yuan)放(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)內置交流(liu)線(xian)路檢測器(qi)(qi)(qi)。這(zhe)控(kong)制(zhi)器(qi)(qi)(qi)在(zai)(zai)檢測到不(bu)再(zai)存在(zai)(zai)交流(liu)信號時，激活內置開關來使(shi)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)放(fang)電(dian)(dian)(dian)(dian)(dian)。有了(le)這(zhe)個功能，就(jiu)不(bu)再(zai)需要(yao)泄(xie)放(fang)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)了(le)，消(xiao)(xiao)(xiao)除了(le)恒定(ding)(ding)的(de)(de)(de)25 mW能耗(hao)源(yuan)頭。

　　次級(ji)端(duan)開(kai)關電(dian)源(yuan)(yuan)控(kong)制(zhi)(zhi)器(qi)（即安森美(mei)半導(dao)(dao)體的NCP4354）是(shi)NCP1246的伴侶IC,能(neng)(neng)(neng)夠(gou)檢測空載(zai)(zai)條件(jian)，并(bing)使電(dian)源(yuan)(yuan)進入低能(neng)(neng)(neng)耗關閉(bi)模式(shi)(shi)。在關閉(bi)模式(shi)(shi)期間，初(chu)(chu)級(ji)端(duan)控(kong)制(zhi)(zhi)器(qi)停止工作，能(neng)(neng)(neng)量由輸(shu)出電(dian)容提(ti)供。適配(pei)器(qi)的輸(shu)出電(dian)壓(ya)開(kai)始下降(jiang)，因為(wei)初(chu)(chu)級(ji)端(duan)不再在存在開(kai)關工作。這(zhe)并(bing)不構成什么問題，因為(wei)適配(pei)器(qi)在此(ci)模式(shi)(shi)下不再連(lian)接至(zhi)筆記本電(dian)腦(nao)。輸(shu)出電(dian)壓(ya)被允(yun)許下降(jiang)至(zhi)某個可調節電(dian)平，直到NCP4354通知初(chu)(chu)級(ji)端(duan)重(zhong)(zhong)啟，重(zhong)(zhong)新(xin)為(wei)輸(shu)出電(dian)容充電(dian)并(bing)因此(ci)維(wei)持工作。當(dang)(dang)適配(pei)器(qi)重(zhong)(zhong)新(xin)連(lian)接至(zhi)電(dian)池時，NCP4354控(kong)制(zhi)(zhi)器(qi)自動重(zhong)(zhong)啟初(chu)(chu)級(ji)端(duan)控(kong)制(zhi)(zhi)器(qi)。能(neng)(neng)(neng)僅以一(yi)顆光耦提(ti)供反饋(kui)控(kong)制(zhi)(zhi)及導(dao)(dao)通/關閉(bi)信號(hao)。當(dang)(dang)在此(ci)類電(dian)路中(zhong)一(yi)起(qi)使用時，NCP1246和NCP4354能(neng)(neng)(neng)夠(gou)采用美(mei)國規格的交(jiao)流主(zhu)電(dian)源(yuan)(yuan)提(ti)供低于10 mW的空載(zai)(zai)能(neng)(neng)(neng)耗，且(qie)在寬交(jiao)流主(zhu)電(dian)源(yuan)(yuan)電(dian)壓(ya)范圍(wei)下提(ti)供低于20 mW的空載(zai)(zai)能(neng)(neng)(neng)耗。

　　圖(tu)4:65 W適配器電路圖(tu)

　　雖然(ran)許多(duo)消費電子(zi)OEM生產(chan)高能(neng)效產(chan)品，但他(ta)們常(chang)常(chang)會對低能(neng)耗(hao)的充(chong)電系(xi)(xi)統感到失望。如今已經出現重要(yao)(yao)進展，電池充(chong)電器可以消耗(hao)更少電能(neng)，同時(shi)提(ti)供市場(chang)所要(yao)(yao)求的高性能(neng)基準(zhun)。諸如本文所介紹的系(xi)(xi)統致力于滿足這些(xie)標準(zhun)，并(bing)降低系(xi)(xi)統復(fu)雜度、節省珍貴的電路板(ban)空間(jian)及使物料單（BOM）成本受到控制。