圖1. USB供電的單節NiMH電池開關模式充電器

       雖然(ran)表面(mian)上Li+電(dian)(dian)池(chi)(chi)已經(jing)占據整個便攜世界，但NiMH電(dian)(dian)池(chi)(chi)并沒有(you)被完全(quan)遺棄。令人吃驚(jing)的(de)(de)(de)是，盡管單位重量(liang)的(de)(de)(de)能量(liang)仍然(ran)有(you)較大(da)差距，但其單位體積的(de)(de)(de)能量(liang)僅比Li+電(dian)(dian)池(chi)(chi)低大(da)約15%。NiMH電(dian)(dian)池(chi)(chi)的(de)(de)(de)最(zui)大(da)缺(que)點是自放電(dian)(dian)率較高(gao)，混合型(xing)NiMH電(dian)(dian)池(chi)(chi)在(zai)很大(da)程度解決(jue)了這一問題，例如SANYO? Eneloop?電(dian)(dian)池(chi)(chi)，靜態下一年之后(hou)仍然(ran)能夠保(bao)留85%的(de)(de)(de)電(dian)(dian)量(liang)。NiMH電(dian)(dian)池(chi)(chi)的(de)(de)(de)吸引力在(zai)于(yu)成本低、安(an)全(quan)性高(gao)、用戶更換方便等，至少標準電(dian)(dian)池(chi)(chi)具備(bei)這些優勢。

      圖1所示便攜設備由一節AA型NiMH電池供電，利用USB充電。DS2710充電器開(kai)關頻(pin)率大(da)約(yue)為150kHz，電(dian)(dian)池充電(dian)(dian)電(dian)(dian)流(liu)(liu)為1.1A (典型(xing)AA型(xing)NiMH電(dian)(dian)池在大(da)約(yue)0.5°C條(tiao)件下(xia)(xia))。由于(yu)降壓轉換器(qi)將5V、500mA轉換成電(dian)(dian)池充電(dian)(dian)時(shi)的(de)(de)1.5V、1.1A，電(dian)(dian)路供給電(dian)(dian)池的(de)(de)電(dian)(dian)流(liu)(liu)(1.1A)大(da)于(yu)從USB接口獲得的(de)(de)電(dian)(dian)流(liu)(liu)(500mA)。需(xu)要注意的(de)(de)是，由于(yu)在低充電(dian)(dian)速率下(xia)(xia)不能(neng)正(zheng)確判(pan)斷(duan)充電(dian)(dian)終止(zhi)(zhi)，只(zhi)能(neng)采(cai)用(yong)500mA或更大(da)功率的(de)(de)端口進行充電(dian)(dian)。所以，當(dang)枚舉確定(ding)(ding)只(zhi)有(you)100mA電(dian)(dian)流(liu)(liu)可用(yong)時(shi)，不應激活充電(dian)(dian)。系統通過關閉TMR上的(de)(de)Q2，使定(ding)(ding)時(shi)器(qi)電(dian)(dian)阻懸空，停止(zhi)(zhi)充電(dian)(dian)。

     該(gai)充(chong)(chong)電(dian)器另外一項(xiang)特別(bie)有用的(de)功能是(shi)：通過檢(jian)測(ce)電(dian)池阻抗確定接入(ru)的(de)是(shi)否為堿(jian)性(xing)電(dian)池或故障電(dian)池，檢(jian)測(ce)到(dao)這種狀況(kuang)(kuang)時將禁止充(chong)(chong)電(dian)。這就允許用戶(hu)在緊(jin)急情況(kuang)(kuang)下(xia)插入(ru)堿(jian)性(xing)電(dian)池，無(wu)需擔(dan)心(xin)意外充(chong)(chong)電(dian)。