圖1. USB供電的單節NiMH電池開關模式充電器

       雖(sui)然表面上Li+電(dian)(dian)(dian)池(chi)(chi)已經(jing)占據整個(ge)便攜世界，但NiMH電(dian)(dian)(dian)池(chi)(chi)并沒有被完全(quan)遺棄。令人吃驚的(de)(de)是，盡管(guan)單(dan)位(wei)重量(liang)的(de)(de)能量(liang)仍然有較(jiao)大(da)差距(ju)，但其單(dan)位(wei)體積的(de)(de)能量(liang)僅比Li+電(dian)(dian)(dian)池(chi)(chi)低大(da)約15%。NiMH電(dian)(dian)(dian)池(chi)(chi)的(de)(de)最大(da)缺(que)點是自放電(dian)(dian)(dian)率較(jiao)高，混合型(xing)NiMH電(dian)(dian)(dian)池(chi)(chi)在(zai)很大(da)程度(du)解決了這一問題，例(li)如SANYO? Eneloop?電(dian)(dian)(dian)池(chi)(chi)，靜態下一年之后仍然能夠保(bao)留85%的(de)(de)電(dian)(dian)(dian)量(liang)。NiMH電(dian)(dian)(dian)池(chi)(chi)的(de)(de)吸(xi)引力在(zai)于成本低、安全(quan)性高、用(yong)戶更換方便等，至少標準電(dian)(dian)(dian)池(chi)(chi)具(ju)備這些(xie)優(you)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(pin)率大(da)約為150kHz，電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流為1.1A (典型AA型NiMH電(dian)(dian)(dian)(dian)池(chi)在大(da)約0.5°C條件(jian)下)。由(you)于降壓轉(zhuan)換(huan)器(qi)將5V、500mA轉(zhuan)換(huan)成(cheng)電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)時的(de)(de)1.5V、1.1A，電(dian)(dian)(dian)(dian)路供給電(dian)(dian)(dian)(dian)池(chi)的(de)(de)電(dian)(dian)(dian)(dian)流(1.1A)大(da)于從USB接口獲得的(de)(de)電(dian)(dian)(dian)(dian)流(500mA)。需要注意(yi)的(de)(de)是，由(you)于在低充(chong)電(dian)(dian)(dian)(dian)速率下不(bu)能(neng)(neng)正(zheng)確判斷充(chong)電(dian)(dian)(dian)(dian)終止(zhi)(zhi)，只能(neng)(neng)采用500mA或更(geng)大(da)功率的(de)(de)端口進行充(chong)電(dian)(dian)(dian)(dian)。所以，當枚(mei)舉確定只有(you)100mA電(dian)(dian)(dian)(dian)流可(ke)用時，不(bu)應激活充(chong)電(dian)(dian)(dian)(dian)。系統(tong)通過關閉TMR上的(de)(de)Q2，使定時器(qi)電(dian)(dian)(dian)(dian)阻懸(xuan)空，停止(zhi)(zhi)充(chong)電(dian)(dian)(dian)(dian)。

     該充(chong)電(dian)(dian)器另外一項特別有(you)用的功(gong)能(neng)是(shi)：通(tong)過檢測(ce)電(dian)(dian)池(chi)阻抗確(que)定接入的是(shi)否(fou)為堿性電(dian)(dian)池(chi)或故障電(dian)(dian)池(chi)，檢測(ce)到這種狀況時將禁止充(chong)電(dian)(dian)。這就允(yun)許用戶在緊急情況下插入堿性電(dian)(dian)池(chi)，無(wu)需擔心意外充(chong)電(dian)(dian)。