思旺電子開發出一款為鋰電池充電器 (萬能充/座充)設計的配套LCD/LED驅動電路SE9120,在顯示電池電量的同時還能顯示充電進度和電池充飽狀態。下(xia)文將重點介紹SE9120的主要技術特點。

　　SE9120主要功能

　　SE9120主要功能包括電池電量檢測及充電進度顯示功能，能夠通過電路內部自動判斷電池極性，自動切換到電池正確的極性，解決用戶在裝載電池時需要人工判斷電池極性的問題。在檢測電池極性的同時，SE9120能夠檢測電池的電量，同時SE9120是第一款創新的用4位分段顯示的方法，驅動4柱LCD屏，使用戶可以查看電池電量的集成電路。

　　SE9120是一款高智(zhi)能(neng)的數模(mo)混合(he)電(dian)(dian)(dian)路，該芯片采用數模(mo)混合(he)方式，通過4位柱(zhu)狀(zhuang)顯(xian)(xian)示(shi)LCD屏或LED屏，在顯(xian)(xian)示(shi)電(dian)(dian)(dian)池電(dian)(dian)(dian)量的同時還能(neng)顯(xian)(xian)示(shi)充(chong)電(dian)(dian)(dian)進度和電(dian)(dian)(dian)池充(chong)飽狀(zhuang)態。SE9120的內部結構如圖(tu)1所示(shi)。主要包括五大(da)功能(neng)模(mo)塊：基準(zhun)電(dian)(dian)(dian)壓單(dan)(dan)元(yuan)(yuan)(yuan)(yuan);電(dian)(dian)(dian)池電(dian)(dian)(dian)量檢測單(dan)(dan)元(yuan)(yuan)(yuan)(yuan);顯(xian)(xian)示(shi)邏輯單(dan)(dan)元(yuan)(yuan)(yuan)(yuan);LCD驅動單(dan)(dan)元(yuan)(yuan)(yuan)(yuan);LED背光驅動單(dan)(dan)元(yuan)(yuan)(yuan)(yuan)。

　　電池電量檢測單(dan)元

　　SE9120通過電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)量檢測單(dan)元(yuan)中(zhong)的(de)B1電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)量信(xin)息單(dan)元(yuan)，探(tan)測到(dao)電(dian)(dian)(dian)(dian)(dian)池(chi)兩端的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)和電(dian)(dian)(dian)(dian)(dian)池(chi)的(de)極(ji)性，然后自動(dong)轉換(huan)(huan)電(dian)(dian)(dian)(dian)(dian)池(chi)極(ji)性，并將電(dian)(dian)(dian)(dian)(dian)池(chi)的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)傳(chuan)送給(gei)B2模(mo)數轉換(huan)(huan)單(dan)元(yuan)，然后模(mo)數控制單(dan)元(yuan)將這個(ge)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)量的(de)信(xin)號(hao)，與內(nei)建精(jing)準(zhun)的(de)基準(zhun)電(dian)(dian)(dian)(dian)(dian)壓(ya)單(dan)元(yuan)提供的(de)參考(kao)電(dian)(dian)(dian)(dian)(dian)壓(ya)進行(xing)比較(jiao)，從而將模(mo)擬的(de)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)量信(xin)號(hao)，轉換(huan)(huan)為數字信(xin)號(hao)，提供給(gei)后級(ji)電(dian)(dian)(dian)(dian)(dian)路。

　　阻抗跟(gen)(gen)蹤(zong)(IT)技(ji)術(shu)(shu)非常獨特(te)，比(bi)現有解決方案更為(wei)精(jing)確，原因是該(gai)技(ji)術(shu)(shu)具(ju)有的(de)自學習(xi)機制能解決導致電池阻抗及(ji)空載條件下化(hua)學全(quan)容量(liang)(QMAX)發生(sheng)變(bian)化(hua)的(de)老化(hua)問題(ti)。阻抗跟(gen)(gen)蹤(zong)技(ji)術(shu)(shu)使(shi)(shi)用(yong)動(dong)態模擬算法(fa)學習(xi)并跟(gen)(gen)蹤(zong)電池特(te)性，即在電池實際(ji)使(shi)(shi)用(yong)過程(cheng)中，先(xian)測量(liang)阻抗及(ji)容量(liang)值(zhi)，然后(hou)跟(gen)(gen)蹤(zong)其(qi)變(bian)化(hua)。使(shi)(shi)用(yong)該(gai)算法(fa)則無需定期(qi)(qi)進行完整周期(qi)(qi)容量(liang)校正(zheng)。

　　利用電(dian)(dian)池阻抗知識，能夠實現(xian)精確的(de)負載及溫(wen)度補償。最(zui)重要的(de)是，通過(guo)對電(dian)(dian)池參(can)數(shu)的(de)動態(tai)學習(xi)，該測量法在(zai)電(dian)(dian)池的(de)整個(ge)使用壽(shou)命(ming)內都能對電(dian)(dian)量進行(xing)精確的(de)測量。與單獨使用庫侖計數(shu)法或(huo)電(dian)(dian)池電(dian)(dian)壓相關(guan)法相比，阻抗跟(gen)蹤技術在(zai)測量電(dian)(dian)池剩余容量方面(mian)更(geng)加出色。

　　顯示邏輯單元

　　顯示(shi)邏(luo)輯(ji)單元(yuan)是整(zheng)個電(dian)路(lu)的(de)核心單元(yuan)，該單元(yuan)需(xu)要將前級輸(shu)送的(de)電(dian)池(chi)電(dian)量(liang)信(xin)息和其他檢(jian)測信(xin)號進行邏(luo)輯(ji)判斷，顯示(shi)邏(luo)輯(ji)單元(yuan)又包括以下幾個重要組成部分(fen)：C1-振蕩器(qi);C2-頻率選擇單元(yuan);C3-電(dian)池(chi)短路(lu)檢(jian)測;C4-電(dian)源電(dian)池(chi)電(dian)壓比較(jiao)單元(yuan);C5-電(dian)池(chi)充飽檢(jian)測。

　　其中(zhong)，振(zhen)蕩(dang)器單元為(wei)(wei)整個(ge)系統提供振(zhen)蕩(dang)信(xin)(xin)號(hao)，由于LCD需要用(yong)開關信(xin)(xin)號(hao)控(kong)制(zhi)，所以振(zhen)蕩(dang)器不僅為(wei)(wei)LCD提供基(ji)準的(de)(de)(de)開關信(xin)(xin)號(hao)，還(huan)作(zuo)為(wei)(wei)邏輯控(kong)制(zhi)信(xin)(xin)號(hao)控(kong)制(zhi)LCD的(de)(de)(de)亮暗。頻率選擇單元將振(zhen)蕩(dang)器輸入的(de)(de)(de)信(xin)(xin)號(hao)進行整合，實現電池電量(liang)分段顯示的(de)(de)(de)功能(neng)：Vbat<3.7V,能(neng)量(liang)低于40%,LCD顯示屏四個(ge)格(ge)全滅;3.7V4.0V,能(neng)量(liang)約為(wei)(wei)100%,LCD顯示屏四個(ge)格(ge)全亮。

　　本方案采用變頻技術，在(zai)顯示充電進(jin)度時，每當一個bar停止閃爍(shuo)時，對(dui)還(huan)在(zai)閃爍(shuo)的(de)其他bar調整頻率。當只(zhi)剩下一個bar閃爍(shuo)時，閃爍(shuo)占(zhan)空(kong)比為50%.

　　電(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)池電(dian)(dian)(dian)壓比較單元通過比較電(dian)(dian)(dian)源(yuan)與電(dian)(dian)(dian)池的(de)(de)電(dian)(dian)(dian)壓，判斷(duan)充(chong)電(dian)(dian)(dian)器是處在只(zhi)(zhi)接電(dian)(dian)(dian)池的(de)(de)狀(zhuang)態(tai)還是充(chong)電(dian)(dian)(dian)狀(zhuang)態(tai)，當只(zhi)(zhi)接電(dian)(dian)(dian)池的(de)(de)狀(zhuang)態(tai)時，SE9120分段顯示電(dian)(dian)(dian)池電(dian)(dian)(dian)量。在充(chong)電(dian)(dian)(dian)狀(zhuang)態(tai)下，SE9120會(hui)控制LCD滾(gun)動顯示。具體分為以下幾種(zhong)情況：Vbat<3.7V,能(neng)量低于40%,LCD四格(ge)滾(gun)動顯示;

　　3.7V4.0V且(qie)C5電池充(chong)飽檢(jian)測(ce)單元檢(jian)測(ce)到電池已(yi)經充(chong)滿，能量約(yue)為100%,LCD顯示屏(ping)四個格全亮。

　　LCD驅動單元

　　該(gai)單元不僅(jin)是給(gei)LCD屏(ping)一個(ge)驅動(dong)，此(ci)外，SE9120還解決了傳統方(fang)(fang)案中，通(tong)過單邊驅動(dong)LCD的(de)方(fang)(fang)法(fa)導致(zhi)低電壓時LCD顯示亮(liang)度不足的(de)問題(ti)。SE9120采用創新的(de)雙(shuang)邊驅動(dong)LCD方(fang)(fang)法(fa)使得電壓較(jiao)低時仍能夠保持較(jiao)高的(de)LCD亮(liang)度。

　　LED背光(guang)驅(qu)動單元

　　該單元智能控制(zhi)LED背(bei)光(guang)功(gong)能，當只接(jie)電池時(shi)，可自動關(guan)閉LED藍色背(bei)光(guang)，因而達到了省電的功(gong)效(xiao)，同時(shi)也減少了電池的消耗。

　　LED背(bei)光(guang)被(bei)用在(zai)小巧(qiao)、廉價的LCD面板上。他的光(guang)通常(chang)是(shi)有顏色(se)(se)(se)的，雖然白(bai)色(se)(se)(se)背(bei)光(guang)已(yi)經(jing)愈來愈普遍(bian)了(le)。電(dian)(dian)光(guang)面板經(jing)常(chang)被(bei)使(shi)用在(zai)大型顯(xian)示(shi)上，這(zhe)(zhe)時(shi)均勻的背(bei)光(guang)是(shi)很重要的。電(dian)(dian)光(guang)面板需(xu)要經(jing)由高(gao)壓(ya)的交流電(dian)(dian)來驅動，這(zhe)(zhe)部份由反用換(huan)流器回路來提(ti)供。冷陰(yin)極管被(bei)用在(zai)像是(shi)電(dian)(dian)腦顯(xian)示(shi)器上，顏色(se)(se)(se)上通常(chang)是(shi)白(bai)色(se)(se)(se)的，這(zhe)(zhe)同樣也需(xu)要反用換(huan)流器和散光(guang)器。白(bai)熾背(bei)光(guang)則(ze)在(zai)需(xu)要高(gao)亮度時(shi)被(bei)使(shi)用，但是(shi)其(qi)缺點則(ze)是(shi)白(bai)熾燈泡的壽(shou)命相當(dang)有限，而且會(hui)產生相當(dang)多的熱量(liang)。