北京2019年9月9日 /美通社/ -- 得益于小型化、Bluetooth®通信和嵌入式(shi)處(chu)理(li)方面的進步，現代助聽器具有比以往(wang)更多的功能，從(cong)流媒(mei)體音樂到能夠通過智能手機上的應(ying)用程(cheng)序(xu)調節(jie)聽力放(fang)大。
然而，要實現這些增強的功能需要付出代價：現代功能需要更多功率。功耗的增加對于設計助聽器的工程師來說是一項挑戰，主要是因為舊版本使用一次性鋅空氣電池。如圖1所示，這些電池的續航能力通常約為兩周。但當為助聽器添加更多功能時，例如讓它們能夠播放音樂，電池續航時間可能會縮短到小時(shi)。因此(ci)，工程師在下一代助聽器設(she)計中使用可充電鋰(li)電池（圖(tu)2）。
可充(chong)(chong)電(dian)(dian)鋰電(dian)(dian)池以多種方式增加(jia)了電(dian)(dian)力系統的(de)(de)復雜性，最重要的(de)(de)是如何安全(quan)準確地(di)為電(dian)(dian)池充(chong)(chong)電(dian)(dian)。使(shi)用兩個助聽器時還有(you)額外的(de)(de)設計(ji)注意事項。因為左右耳機沒有(you)物理連接，所(suo)以無法同時通(tong)過單(dan)根電(dian)(dian)纜對其進行充(chong)(chong)電(dian)(dian)。因此，幾乎所(suo)有(you)新(xin)型助聽器現(xian)在都配備了具有(you)充(chong)(chong)電(dian)(dian)和(he)儲電(dian)(dian)功能的(de)(de)盒(he)子。
該盒(he)子為(wei)(wei)每個耳(er)(er)機設計了特(te)定的(de)插孔，以(yi)確(que)保正確(que)的(de)充(chong)電(dian)。耳(er)(er)機的(de)充(chong)電(dian)必須精確(que)，因為(wei)(wei)可(ke)充(chong)電(dian)助聽器通(tong)常(chang)為(wei)(wei)25 mAh-75 mAh，充(chong)電(dian)盒(he)的(de)范圍為(wei)(wei)300 mAh -70 0mAh。這意味著，在盒(he)子需要(yao)重新(xin)充(chong)電(dian)之前，耳(er)(er)機的(de)使用時間大約為(wei)(wei)24小時，充(chong)電(dian)周(zhou)期大約為(wei)(wei)10次。
有了(le)充(chong)電(dian)盒，助聽(ting)器(qi)設計師現在可考慮使用(yong)(yong)三種(zhong)不同的鋰電(dian)池(chi)：一種(zhong)用(yong)(yong)于(yu)充(chong)電(dian)盒，另外兩種(zhong)用(yong)(yong)于(yu)耳機。電(dian)池(chi)充(chong)電(dian)器(qi)的選擇在設計中起著重要作用(yong)(yong)。
同樣要(yao)注(zhu)意(yi)的是，通(tong)過電(dian)(dian)(dian)(dian)(dian)池(chi)為電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)（即(ji)(ji)，通(tong)過充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)盒電(dian)(dian)(dian)(dian)(dian)池(chi)為耳(er)(er)機(ji)電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)）并不像通(tong)過墻壁插(cha)座(zuo)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)那么(me)簡單(dan)，因為兩個電(dian)(dian)(dian)(dian)(dian)池(chi)之間的電(dian)(dian)(dian)(dian)(dian)壓差不會很大。必須有(you)內(nei)部電(dian)(dian)(dian)(dian)(dian)路(lu)來增強充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)盒和耳(er)(er)機(ji)之間的電(dian)(dian)(dian)(dian)(dian)壓差，以實現完(wan)全(quan)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)。隨著電(dian)(dian)(dian)(dian)(dian)池(chi)放電(dian)(dian)(dian)(dian)(dian)，其(qi)電(dian)(dian)(dian)(dian)(dian)壓正在緩慢下降。觀察(cha)圖(tu)3所(suo)示(shi)的放電(dian)(dian)(dian)(dian)(dian)曲線(xian)，電(dian)(dian)(dian)(dian)(dian)池(chi)容(rong)量約為50%時，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)盒電(dian)(dian)(dian)(dian)(dian)壓約為3.6 V。但這意(yi)味著如果沒有(you)升壓，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)盒只能(neng)為最(zui)高3.6 V的耳(er)(er)機(ji)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，即(ji)(ji)使存儲在充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)盒中的能(neng)量足以使它們完(wan)全(quan)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)。
這種情(qing)況下(xia)，大多數工程(cheng)師會(hui)考慮謹慎升壓。雖然謹慎升壓確實有效(xiao)，但它通常會(hui)通過在電源架(jia)構(gou)中增(zeng)加額外升壓和(he)電感器組件來增(zeng)加解決(jue)方案尺寸和(he)低效(xiao)率。
要攻克這些挑戰，請考慮靜態電(dian)流支(zhi)持的(de)便(bian)攜(xie)充(chong)(chong)電(dian)。例如，TI的(de)BQ25619電(dian)池充(chong)(chong)電(dian)器和(he)BQ25155線(xian)性充(chong)(chong)電(dian)器支(zhi)持在沒(mei)有外部(bu)增壓(ya)的(de)情況下充(chong)(chong)電(dian)。在助聽器應用(yong)中，使用(yong)者可將BQ25619置于充(chong)(chong)電(dian)盒中，將BQ25155置于每(mei)個耳機內(nei)。
而且(qie)，并非(fei)總需要將充電盒輸出升(sheng)壓至5V，通(tong)過(guo)使用BQ25619的升(sheng)壓功能，可以增強(qiang)到所需的最低電壓，以便在充電盒和耳機電池之間留出足夠的凈空高(gao)度。這減(jian)少了不必要的升(sheng)壓功率損失且(qie)還增加(jia)了耳機充電效率，因為降(jiang)低了電壓差。
BQ25155非常適用(yong)于耳機，因為它的(de)(de)最(zui)小(xiao)3.4V輸入(ru)電(dian)(dian)壓可(ke)(ke)在沒有升(sheng)壓的(de)(de)情況下(xia)實(shi)現更長的(de)(de)充(chong)電(dian)(dian)，其43μA的(de)(de)靜態(tai)電(dian)(dian)流可(ke)(ke)增加電(dian)(dian)池(chi)的(de)(de)運行(xing)時間。同時，BQ25619在出廠模式下(xia)的(de)(de)7μA靜態(tai)電(dian)(dian)流可(ke)(ke)最(zui)大限度地延長充(chong)電(dian)(dian)盒的(de)(de)使用(yong)壽命。BQ25619的(de)(de)20mA充(chong)電(dian)(dian)終止(zhi)電(dian)(dian)流使其能(neng)夠為小(xiao)型電(dian)(dian)池(chi)充(chong)電(dian)(dian)，容(rong)量增加7%。
好消息(xi)是這(zhe)些優勢不僅只局限于助聽(ting)器：包括耳塞和(he)可(ke)穿戴貼片(pian)等(deng)所有雙電池器件系統(tong)都可(ke)從(cong)這(zhe)些創新中(zhong)受益。TI將在未來的設計中(zhong)將繼續采用(yong)雙充電器配置，其特點如(ru)下：
使用BQ25619和BQ25155，使用者可在不增加成本或(huo)解決方案尺寸的情(qing)況下改善可從充電(dian)盒中(zhong)提取的充電(dian)周(zhou)期數。
其它資源
