圖1. USB供電的單節NiMH電池開關模式充電器

       雖然(ran)表面上Li+電(dian)池(chi)已經占(zhan)據整個便攜世界，但NiMH電(dian)池(chi)并(bing)沒有被完(wan)全遺(yi)棄。令人吃驚的(de)是，盡管單位重量的(de)能(neng)量仍(reng)然(ran)有較大(da)差距，但其單位體(ti)積的(de)能(neng)量僅比Li+電(dian)池(chi)低(di)大(da)約15%。NiMH電(dian)池(chi)的(de)最大(da)缺點是自放電(dian)率較高(gao)，混合型NiMH電(dian)池(chi)在很大(da)程度解決了這一問題，例如SANYO? Eneloop?電(dian)池(chi)，靜態下(xia)一年之后仍(reng)然(ran)能(neng)夠保留(liu)85%的(de)電(dian)量。NiMH電(dian)池(chi)的(de)吸引力在于成本(ben)低(di)、安全性(xing)高(gao)、用戶(hu)更(geng)換方便等，至少標(biao)準電(dian)池(chi)具備這些優勢。

      圖1所示便攜設備由一節AA型NiMH電池供電，利用USB充電。DS2710充電器開關頻率(lv)大約為(wei)150kHz，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)為(wei)1.1A (典(dian)型(xing)AA型(xing)NiMH電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)在大約0.5°C條(tiao)件下)。由于(yu)降壓轉(zhuan)換器將5V、500mA轉(zhuan)換成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)時的(de)(de)(de)1.5V、1.1A，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)供給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(1.1A)大于(yu)從USB接口獲得的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(500mA)。需要注意的(de)(de)(de)是，由于(yu)在低充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)速率(lv)下不(bu)能(neng)正(zheng)確判(pan)斷充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)終止(zhi)，只能(neng)采用(yong)500mA或更大功率(lv)的(de)(de)(de)端口進行充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。所以，當(dang)枚舉確定只有(you)100mA電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)可用(yong)時，不(bu)應(ying)激活充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。系統通過關閉(bi)TMR上的(de)(de)(de)Q2，使(shi)定時器電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)懸(xuan)空(kong)，停止(zhi)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。

     該充(chong)(chong)電(dian)器另外一(yi)項特(te)別有用(yong)的(de)功能是(shi)(shi)：通過檢(jian)測電(dian)池阻抗確定接入(ru)的(de)是(shi)(shi)否為堿性電(dian)池或故障電(dian)池，檢(jian)測到這種狀況時將(jiang)禁(jin)止充(chong)(chong)電(dian)。這就(jiu)允許用(yong)戶在(zai)緊(jin)急情況下插入(ru)堿性電(dian)池，無(wu)需(xu)擔心意外充(chong)(chong)電(dian)。