GM6801實現智能快速充電器
應(ying)用(yong)比較廣泛快(kuai)速充電(dian)管理(li)芯(xin)片基(ji)本(ben)上有(you)兩種類型。一(yi)種是(shi)單片機，另(ling)一(yi)種是(shi)快(kuai)速充電(dian)管理(li)專用(yong)集成電(dian)路。成都國騰微電(dian)子(zi)有(you)限公司(si)成功開發(fa)出一(yi)款鎳氫/鎳鎘電(dian)池快(kuai)速充電(dian)智能管理(li)芯(xin)片――GM6801。該(gai)芯(xin)片外部管腳控制(zhi)功能可編程，無需外部控制(zhi)器支持，使充電(dian)過程檢測控制(zhi)完(wan)全自動化，所需外圍器件少，應(ying)用(yong)設(she)計(ji)簡單。
GM6801應用方案優勢(shi)
GM6801是快(kuai)速充電(dian)(dian)管理專用集成電(dian)(dian)路。與(yu)單(dan)片(pian)機相比，由(you)專用集成電(dian)(dian)路實(shi)現(xian)快(kuai)速充電(dian)(dian)管理優勢主要體現(xian)在幾(ji)個(ge)方面：
1. 專用集成(cheng)電路在硬件中集成(cheng)了對快速充(chong)電管(guan)理全部算法(fa)，無需開(kai)發控制軟件，從(cong)而有效(xiao)縮短產品設計周期(qi)，簡化設計流(liu)程(cheng)，所需外(wai)圍器件少，使應用設計變得簡單；
2. 采用單片機實現中高端快速充電器時，對單(dan)片機(ji)有較(jiao)高要求(qiu)，比如需要較(jiao)多(duo)I/O口，需要自帶AD等，還要開(kai)發相關(guan)軟件，這樣采用(yong)單(dan)片機(ji)所需成(cheng)本往(wang)往(wang)較(jiao)高；
3. 專用集成電(dian)(dian)(dian)路可(ke)以(yi)實現對(dui)快速充電(dian)(dian)(dian)過(guo)程(cheng)精確控(kong)制，比如GM6801就采用了帶(dai)瞬間(jian)放電(dian)(dian)(dian)過(guo)程(cheng)脈沖充電(dian)(dian)(dian)形式。這(zhe)樣可(ke)以(yi)在快速充電(dian)(dian)(dian)過(guo)程(cheng)中及時(shi)消除大電(dian)(dian)(dian)流造成電(dian)(dian)(dian)極化效應，使電(dian)(dian)(dian)池充電(dian)(dian)(dian)效果更佳(jia)；
4. 由于快速充電器涉及安全問題，專用(yong)集(ji)成(cheng)電(dian)路良(liang)好一致性和穩(wen)定性相對普通單(dan)片機(ji)來(lai)說(shuo)更具優勢(shi)。
此外(wai)，GM6801本身采(cai)用(yong)一些個性化設計(ji)：GM6801內置(zhi)10位(wei)AD轉(zhuan)換器，可以(yi)實時(shi)采(cai)集每節(jie)電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)和溫度信(xin)息(xi)，自(zi)帶(dai)“Condition fit”功(gong)能能夠避免(mian)環境變化帶(dai)來干擾，保(bao)證對(dui)(dui)快速充電(dian)(dian)(dian)(dian)/放電(dian)(dian)(dian)(dian)過(guo)(guo)程(cheng)檢測(ce)判斷(duan)準(zhun)確可靠。GM6801對(dui)(dui)每節(jie)電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)/放電(dian)(dian)(dian)(dian)過(guo)(guo)程(cheng)檢測(ce)判斷(duan)方(fang)法有電(dian)(dian)(dian)(dian)壓(ya)負增長(-ΔV)、最大電(dian)(dian)(dian)(dian)壓(ya)、最大充電(dian)(dian)(dian)(dian)時(shi)間、最高溫度四種方(fang)式，通過(guo)(guo)多參數評估來進行綜合判斷(duan)，以(yi)確保(bao)電(dian)(dian)(dian)(dian)池(chi)被最大化充滿，同(tong)時(shi)避免(mian)過(guo)(guo)充，從(cong)而延長電(dian)(dian)(dian)(dian)池(chi)使(shi)用(yong)壽命。
GM6801自(zi)動判斷電(dian)(dian)池(chi)有效性、自(zi)動識別電(dian)(dian)池(chi)種類，具備(bei)(bei)超溫(wen)(wen)保(bao)護和最大充電(dian)(dian)時(shi)間(jian)保(bao)護，保(bao)證(zheng)了充電(dian)(dian)過程安全性。更完(wan)善功(gong)能包括：可(ke)直(zhi)接驅動4個雙色LED顯示(shi)(shi)各個電(dian)(dian)池(chi)狀(zhuang)態；可(ke)對(dui)充電(dian)(dian)/放電(dian)(dian)狀(zhuang)態進行聲(sheng)音提示(shi)(shi)；在高(gao)溫(wen)(wen)情況(kuang)下可(ke)以自(zi)動啟(qi)動風扇；具備(bei)(bei)充電(dian)(dian)/放電(dian)(dian)狀(zhuang)態數(shu)據輸出功(gong)能，可(ke)直(zhi)觀顯示(shi)(shi)各個電(dian)(dian)池(chi)電(dian)(dian)量。
GM6801解決方案設計
GM6801應用方案如(ru)圖1所示，設計第一步需要確定(ding)智能快速(su)充(chong)電(dian)(dian)器(qi)電(dian)(dian)源電(dian)(dian)流。根(gen)據(ju)充(chong)電(dian)(dian)電(dian)(dian)池容量以及想要達到充(chong)電(dian)(dian)速(su)度，可(ke)以計算出快速(su)充(chong)電(dian)(dian)器(qi)電(dian)(dian)源電(dian)(dian)流值。
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圖1：GM6801應用方案示意圖
例如，設計一個針對2,000mAh充電電池充電器，若需要把充滿兩節電池最大時間控制在90分鐘以內，那么根據GM6801數據手冊中相關參數可以確定充電時間為1C，由此確定平均充電電流IC=2,000mA。放電電流Idischg由放電回路電阻值確定，假定放電電流IDISCHG≈1,000mA，再(zai)根據GM6801數據手冊中(zhong)計算公式可以推(tui)算出(chu)充電器電源實際電流值為：
ICHG＝(IC IDISCHG/32)×(64/31)＝(2,000mA 1,000mA/32)×(64/31)≈4,200mA。
即設(she)計(ji)充(chong)電(dian)器(qi)時，充(chong)電(dian)器(qi)電(dian)源電(dian)流值應該設(she)計(ji)成等于(yu)或略大于(yu)4,200mA。另外需要強調是，選(xuan)擇熱敏電(dian)阻非常重要。
熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)是GM6801應用(yong)系統中采集溫度(du)關鍵元件(jian)。在GM6801應用(yong)電(dian)(dian)(dian)(dian)路中，熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)必須直接(jie)(jie)或通(tong)過導熱(re)材料與被測電(dian)(dian)(dian)(dian)池(chi)緊(jin)密接(jie)(jie)觸(chu)。熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)B值(zhi)=3,300K，熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)值(zhi)根(gen)據(ju)應用(yong)電(dian)(dian)(dian)(dian)路確定，按照GM6801數(shu)據(ju)手(shou)冊中提供(gong)應用(yong)電(dian)(dian)(dian)(dian)路(如圖2所示)，熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(RT)與一(yi)(yi)個電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)(R)串聯，電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)另一(yi)(yi)端連(lian)接(jie)(jie) 5V電(dian)(dian)(dian)(dian)源(Vi)，熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)另一(yi)(yi)端接(jie)(jie)地，熱(re)敏電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)與電(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)連(lian)接(jie)(jie)點引出反(fan)應溫度(du)變化電(dian)(dian)(dian)(dian)壓采樣(yang)信息(Vt)。
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圖2：GM6801應用方案中熱敏電阻應用電路示意圖
要求在不(bu)同溫(wen)度(du)(du)點采(cai)集到(dao)電壓Vt值(zhi)與GM6801數(shu)據手冊中(zhong)提供(gong)數(shu)據基本一致，這樣才(cai)能保證由該熱敏電阻網(wang)絡采(cai)集到(dao)電池溫(wen)度(du)(du)信息(xi)與設計中(zhong)溫(wen)度(du)(du)刻(ke)度(du)(du)一致。推(tui)薦RT和(he)R標稱值(zhi)都采(cai)用27kΩ(25℃時)。
接下來，需要完(wan)成一些控制引腳和(he)輸入輸出引腳設定(ding)。
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圖3：GM6801控制部分應用電路圖
如圖3所示，在GM6801應用電路中，鎳氫/鎳鎘電池選擇引腳(NH/ND)與一個外部開關連接，通過開關選擇該引腳接高電平或低電平來決定充電電池類型，低電平為鎳氫，高電平為鎳鎘，當該引腳狀態改變時，同時具有復位功能；充電/放電選擇引腳(CHG/DISCHG)與一個外部開關連接，通過開關選擇該引腳接高電平或低電平來決定充電或放電，低電平為充電，高電平為放電；充電時間選擇引腳(CHGTIME0/CHGTIME1)分別與外部電路連接，通過設定該引腳接高電平或低電平，由CHGTIME0/CHGTIME1兩個引腳狀態決定充電時間(即C值)。
GM6801系列QFP44封(feng)裝芯(xin)片采用(yong)四路(lu)充(chong)電(dian)/放電(dian)回路(lu)獨立(li)控(kong)制，可對最多4節不同(tong)型號、容(rong)量接近(jin)鎳(nie)氫/鎳(nie)鎘電(dian)池(chi)任意(yi)組合進行并(bing)聯充(chong)電(dian)/放電(dian)管理(li)。如圖4所示，在應(ying)用(yong)于四路(lu)并(bing)聯充(chong)電(dian)/放電(dian)控(kong)制方(fang)式(shi)時，GM6801VCC和Vref通(tong)常接 5V，其中Vref要求加10uF旁路(lu)電(dian)容(rong)增加穩定性。工作時鐘選用(yong)32.768kHz無源晶振。
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圖4：GM6801應用于四路并聯充電/放電管理方案輸入輸出部分電路圖
GM6801分(fen)(fen)別(bie)提供充電(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)輸(shu)(shu)出(chu)(chu)(chu)(chu)、放(fang)(fang)電(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)輸(shu)(shu)出(chu)(chu)(chu)(chu)、電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓采(cai)集輸(shu)(shu)入(ru)(ru)、風扇(shan)(shan)驅(qu)動輸(shu)(shu)出(chu)(chu)(chu)(chu)、蜂(feng)鳴(ming)(ming)器(qi)輸(shu)(shu)出(chu)(chu)(chu)(chu)、雙(shuang)色(se)(se)(se)(se)LED控(kong)制(zhi)(zhi)(zhi)輸(shu)(shu)出(chu)(chu)(chu)(chu)以及串(chuan)行數(shu)據(ju)輸(shu)(shu)出(chu)(chu)(chu)(chu)，這些功能管(guan)腳定義(yi)和功能分(fen)(fen)別(bie)為：充電(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)輸(shu)(shu)出(chu)(chu)(chu)(chu)(CHGCTRL1~4)高(gao)(gao)電(dian)(dian)(dian)平(ping)有效(xiao)，控(kong)制(zhi)(zhi)(zhi)對應(ying)充電(dian)(dian)(dian)回路開(kai)關(guan)打開(kai)或關(guan)閉；放(fang)(fang)電(dian)(dian)(dian)控(kong)制(zhi)(zhi)(zhi)輸(shu)(shu)出(chu)(chu)(chu)(chu)(DISCHG1~4)低(di)電(dian)(dian)(dian)平(ping)有效(xiao)，控(kong)制(zhi)(zhi)(zhi)對應(ying)放(fang)(fang)電(dian)(dian)(dian)回路開(kai)關(guan)打開(kai)或關(guan)閉；電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓采(cai)集輸(shu)(shu)入(ru)(ru)口(kou)(CELVOLT1~4)分(fen)(fen)別(bie)與(yu)(yu)四(si)路充電(dian)(dian)(dian)回路中一(yi)個(ge)電(dian)(dian)(dian)池(chi)正(zheng)極(ji)相(xiang)(xiang)連，用(yong)于采(cai)集每節電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓值；電(dian)(dian)(dian)池(chi)溫度(du)采(cai)集輸(shu)(shu)入(ru)(ru)口(kou)(CELTMP1~4)分(fen)(fen)別(bie)與(yu)(yu)四(si)個(ge)溫度(du)傳感器(qi)中一(yi)個(ge)相(xiang)(xiang)連，采(cai)集相(xiang)(xiang)應(ying)電(dian)(dian)(dian)池(chi)溫度(du)信(xin)息；風扇(shan)(shan)驅(qu)動輸(shu)(shu)出(chu)(chu)(chu)(chu)(FANDRV)高(gao)(gao)電(dian)(dian)(dian)平(ping)有效(xiao)，與(yu)(yu)風扇(shan)(shan)正(zheng)輸(shu)(shu)入(ru)(ru)腳相(xiang)(xiang)連，在(zai)一(yi)定條(tiao)件(jian)下可直接驅(qu)動風扇(shan)(shan)；蜂(feng)鳴(ming)(ming)器(qi)輸(shu)(shu)出(chu)(chu)(chu)(chu)(BUZZER)高(gao)(gao)電(dian)(dian)(dian)平(ping)有效(xiao)，與(yu)(yu)蜂(feng)鳴(ming)(ming)器(qi)正(zheng)輸(shu)(shu)入(ru)(ru)腳相(xiang)(xiang)連，在(zai)一(yi)定條(tiao)件(jian)下可直接驅(qu)動蜂(feng)鳴(ming)(ming)器(qi)；顯示(shi)電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)/放(fang)(fang)電(dian)(dian)(dian)狀態雙(shuang)色(se)(se)(se)(se)LED控(kong)制(zhi)(zhi)(zhi)輸(shu)(shu)出(chu)(chu)(chu)(chu)(LED1A/LED1B~LED4A/LED4B)低(di)電(dian)(dian)(dian)平(ping)有效(xiao)，其中LED1A~4A分(fen)(fen)別(bie)與(yu)(yu)四(si)個(ge)雙(shuang)色(se)(se)(se)(se)LED紅(hong)色(se)(se)(se)(se)極(ji)陰極(ji)相(xiang)(xiang)連，LED1B~4B分(fen)(fen)別(bie)與(yu)(yu)四(si)個(ge)雙(shuang)色(se)(se)(se)(se)LED綠(lv)色(se)(se)(se)(se)極(ji)陰極(ji)相(xiang)(xiang)連，這四(si)個(ge)雙(shuang)色(se)(se)(se)(se)LED采(cai)用(yong)共陽極(ji)方式；串(chuan)行數(shu)據(ju)輸(shu)(shu)出(chu)(chu)(chu)(chu)引腳(SERIES_OUT)以串(chuan)行數(shu)據(ju)方式實時(shi)送出(chu)(chu)(chu)(chu)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)量信(xin)息，用(yong)于直觀顯示(shi)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)量。
GM6801系(xi)列QFP44封(feng)裝芯片也可以對(dui)串(chuan)聯電(dian)池(chi)組進行(xing)充(chong)電(dian)/放電(dian)管理。在(zai)針對(dui)串(chuan)聯電(dian)池(chi)組進行(xing)充(chong)電(dian)/放電(dian)控(kong)制時，只需(xu)要GM6801其中一路(lu)充(chong)電(dian)/放電(dian)控(kong)制回路(lu)即(ji)可實現。
例(li)如(ru)：設定對一個四節電(dian)池(chi)串聯電(dian)池(chi)組進(jin)行(xing)充(chong)電(dian)/放電(dian)，采(cai)用GM6801第(di)一個控制(zhi)回路進(jin)行(xing)充(chong)電(dian)/放電(dian)管理。
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圖5：GM6801應用于串聯電池組充電/放電管理方案輸入輸出部分電路圖
應(ying)用(yong)方案如圖5所示(shi)，在針對(dui)串聯電(dian)(dian)(dian)(dian)(dian)(dian)池組(zu)充電(dian)(dian)(dian)(dian)(dian)(dian)/放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)管理方案中，GM6801控制引腳和輸入(ru)輸出引腳設定(ding)與并(bing)聯充電(dian)(dian)(dian)(dian)(dian)(dian)/放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)管理不同之處為：電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)采(cai)集輸入(ru)口(kou)(這里取CELVOLT1)通(tong)過一個(ge)分壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)與串聯電(dian)(dian)(dian)(dian)(dian)(dian)池組(zu)正極相連，串聯電(dian)(dian)(dian)(dian)(dian)(dian)池組(zu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)值經過分壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)把相當于一節(jie)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)值送到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)采(cai)集輸入(ru)口(kou)(CELVOLT1)；原來為了實現(xian)自動判斷充電(dian)(dian)(dian)(dian)(dian)(dian)/放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)回(hui)路(lu)是(shi)否(fou)有電(dian)(dian)(dian)(dian)(dian)(dian)池而(er)在電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)采(cai)集輸入(ru)口(kou)(CELVOLT1)之前加 5V上拉電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)不再適用(yong)，去(qu)掉該上拉電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)后，充電(dian)(dian)(dian)(dian)(dian)(dian)/放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)開(kai)始由芯片使能開(kai)關控制，當芯片使能開(kai)關接(jie)通(tong)地電(dian)(dian)(dian)(dian)(dian)(dian)位(GND)時，開(kai)始充電(dian)(dian)(dian)(dian)(dian)(dian)/放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)，充電(dian)(dian)(dian)(dian)(dian)(dian)/放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)過程管理及控制由GM6801自動完成。當芯片使能開(kai)關接(jie)通(tong) 5V時，芯片停止工(gong)作(zuo)。