1、電(dian)池(chi)保護板正常狀態

鋰電池保護板在正常狀態下(xia)電(dian)路中(zhong)N1的“CO”與(yu)“DO”腳都輸(shu)出高(gao)電(dian)壓，兩(liang)個MOSFET都處于(yu)導通(tong)狀態，電(dian)池(chi)可以自由地進行充電(dian)和放電(dian)，由于(yu)MOSFET的導通(tong)阻(zu)抗(kang)很(hen)小(xiao)，通(tong)常小(xiao)于(yu)30毫歐(ou)，因此其導通(tong)電(dian)阻(zu)對電(dian)路的性能影響很(hen)小(xiao)。此狀態下(xia)保(bao)護電(dian)路的消耗電(dian)流為μA級，通(tong)常小(xiao)于(yu)7μA。

2、過充電保護

鋰離子電池要(yao)求的充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)方式為(wei)(wei)恒(heng)流/恒(heng)壓(ya)(ya)(ya)(ya)，在(zai)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)初期，為(wei)(wei)恒(heng)流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，隨著充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)會(hui)上升到(dao)4.2V(根據(ju)正極材(cai)料不(bu)同(tong)，有(you)的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)要(yao)求恒(heng)壓(ya)(ya)(ya)(ya)值(zhi)為(wei)(wei)4.1V)，轉(zhuan)為(wei)(wei)恒(heng)壓(ya)(ya)(ya)(ya)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，直至電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流越來(lai)越小(xiao)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)在(zai)被充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程中，如(ru)果充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)失(shi)去(qu)控(kong)(kong)制(zhi)，會(hui)使(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)超(chao)過(guo)4.2V后繼續(xu)恒(heng)流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，此(ci)時(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)仍(reng)會(hui)繼續(xu)上升，當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)被充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)至超(chao)過(guo)4.3V時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的化學副反(fan)應將加劇，會(hui)導(dao)致電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)損壞或出現安全問題。在(zai)帶有(you)保護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)中，當控(kong)(kong)制(zhi)IC檢測到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)達(da)到(dao)4.28V(該值(zhi)由(you)控(kong)(kong)制(zhi)IC決定(ding)，不(bu)同(tong)的IC有(you)不(bu)同(tong)的值(zhi))時(shi)(shi)，其“CO”腳將由(you)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)轉(zhuan)變為(wei)(wei)零電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，使(shi)V2由(you)導(dao)通轉(zhuan)為(wei)(wei)關斷，從而切斷了充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)回路(lu)，使(shi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器無(wu)法(fa)再對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)進行(xing)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，起到(dao)過(guo)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)保護作用。而此(ci)時(shi)(shi)由(you)于V2自帶的體二極管VD2的存在(zai)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)可(ke)以通過(guo)該二極管對(dui)外(wai)部負(fu)載進行(xing)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。在(zai)控(kong)(kong)制(zhi)IC檢測到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)超(chao)過(guo)4.28V至發出關斷V2信號之間(jian)(jian)，還有(you)一段延時(shi)(shi)時(shi)(shi)間(jian)(jian)，該延時(shi)(shi)時(shi)(shi)間(jian)(jian)的長短由(you)C3決定(ding)，通常(chang)設為(wei)(wei)1秒(miao)左右，以避(bi)免因干擾而造成誤判斷。

3、短路保護

電池在對負載(zai)(zai)(zai)放電過程中(zhong)，若回路(lu)電流(liu)大(da)到使U>0.9V(該值由(you)控制(zhi)IC決定，不(bu)同(tong)的(de)(de)IC有不(bu)同(tong)的(de)(de)值)時(shi)，控制(zhi)IC則(ze)判斷(duan)為(wei)負載(zai)(zai)(zai)短路(lu)，其(qi)“DO”腳將(jiang)迅速由(you)高(gao)電壓(ya)轉(zhuan)(zhuan)變為(wei)零電壓(ya)，使V1由(you)導(dao)通(tong)轉(zhuan)(zhuan)為(wei)關(guan)斷(duan)，從而切(qie)斷(duan)放電回路(lu)，起(qi)(qi)到短路(lu)保(bao)護(hu)作用。短路(lu)保(bao)護(hu)的(de)(de)延(yan)時(shi)時(shi)間極(ji)短，通(tong)常小(xiao)于(yu)7微秒。其(qi)工作原(yuan)理與過電流(liu)保(bao)護(hu)類似(si)，只是判斷(duan)方法不(bu)同(tong)，保(bao)護(hu)延(yan)時(shi)時(shi)間也(ye)不(bu)一樣(yang)。除(chu)了控制(zhi)IC外(wai)，電路(lu)中(zhong)還有一個重要元件，就是MOSFET，它在電路(lu)中(zhong)起(qi)(qi)著開(kai)關(guan)的(de)(de)作用，由(you)于(yu)它直接(jie)串接(jie)在電池與外(wai)部負載(zai)(zai)(zai)之間，因(yin)此它的(de)(de)導(dao)通(tong)阻(zu)抗(kang)對電池的(de)(de)性(xing)能(neng)(neng)有影響(xiang)，當選用的(de)(de)MOSFET較好時(shi)，其(qi)導(dao)通(tong)阻(zu)抗(kang)很小(xiao)，電池包的(de)(de)內阻(zu)就小(xiao)，帶(dai)載(zai)(zai)(zai)能(neng)(neng)力也(ye)強，在放電時(shi)其(qi)消耗的(de)(de)電能(neng)(neng)也(ye)少。

4、過電流保護

由于(yu)鋰離子電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)(de)化(hua)學特性，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)生(sheng)(sheng)產(chan)廠家規定了其放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流最(zui)大(da)不(bu)能超過(guo)(guo)(guo)2C(C=電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)容量(liang)/小(xiao)(xiao)時)，當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)超過(guo)(guo)(guo)2C電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)時，將(jiang)會導(dao)致電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)(de)永久性損壞(huai)或出(chu)現安(an)全問題(ti)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)在(zai)(zai)對負載(zai)正常(chang)(chang)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)(guo)(guo)程中，放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流在(zai)(zai)經過(guo)(guo)(guo)串聯的(de)(de)(de)(de)2個(ge)(ge)MOSFET時，由于(yu)MOSFET的(de)(de)(de)(de)導(dao)通(tong)阻(zu)抗，會在(zai)(zai)其兩(liang)端產(chan)生(sheng)(sheng)一個(ge)(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓，該(gai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓值(zhi)(zhi)U=I*RDS*2，RDS為(wei)單個(ge)(ge)MOSFET導(dao)通(tong)阻(zu)抗，控(kong)(kong)制(zhi)IC上的(de)(de)(de)(de)“V-”腳(jiao)對該(gai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓值(zhi)(zhi)進行檢測(ce)，若負載(zai)因(yin)某種原(yuan)因(yin)導(dao)致異常(chang)(chang)，使(shi)回路(lu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流增大(da)，當回路(lu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流大(da)到(dao)使(shi)U>0.1V(該(gai)值(zhi)(zhi)由控(kong)(kong)制(zhi)IC決(jue)定，不(bu)同(tong)的(de)(de)(de)(de)IC有(you)不(bu)同(tong)的(de)(de)(de)(de)值(zhi)(zhi))時，其“DO”腳(jiao)將(jiang)由高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓轉變為(wei)零電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓，使(shi)V1由導(dao)通(tong)轉為(wei)關斷(duan)，從而(er)切斷(duan)了放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)回路(lu)，使(shi)回路(lu)中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流為(wei)零，起(qi)到(dao)過(guo)(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流保護作(zuo)用。在(zai)(zai)控(kong)(kong)制(zhi)IC檢測(ce)到(dao)過(guo)(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流發(fa)生(sheng)(sheng)至發(fa)出(chu)關斷(duan)V1信號之間(jian)，也有(you)一段延(yan)時時間(jian)，該(gai)延(yan)時時間(jian)的(de)(de)(de)(de)長短由C3決(jue)定，通(tong)常(chang)(chang)為(wei)13毫秒左右，以(yi)避(bi)免因(yin)干擾(rao)而(er)造成誤判斷(duan)。在(zai)(zai)上述控(kong)(kong)制(zhi)過(guo)(guo)(guo)程中可(ke)知，其過(guo)(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流檢測(ce)值(zhi)(zhi)大(da)小(xiao)(xiao)不(bu)僅取決(jue)于(yu)控(kong)(kong)制(zhi)IC的(de)(de)(de)(de)控(kong)(kong)制(zhi)值(zhi)(zhi)，還取決(jue)于(yu)MOSFET的(de)(de)(de)(de)導(dao)通(tong)阻(zu)抗，當MOSFET導(dao)通(tong)阻(zu)抗越大(da)時，對同(tong)樣的(de)(de)(de)(de)控(kong)(kong)制(zhi)IC，其過(guo)(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流保護值(zhi)(zhi)越小(xiao)(xiao)。

5、過放電保護

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)在對(dui)外部負載(zai)(zai)放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程中，其(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)會(hui)(hui)隨著放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程逐漸降低(di)，當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)降至2.5V時(shi)(shi)(shi)(shi)，其(qi)容(rong)量已被完全(quan)放(fang)(fang)(fang)(fang)光，此時(shi)(shi)(shi)(shi)如果讓電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)繼續對(dui)負載(zai)(zai)放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，將造成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)(de)永久性損(sun)壞(huai)。在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程中，當控(kong)制IC檢(jian)測(ce)到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)低(di)于(yu)2.3V(該值由(you)控(kong)制IC決定，不同的(de)(de)IC有不同的(de)(de)值)時(shi)(shi)(shi)(shi)，其(qi)“DO”腳將由(you)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)轉(zhuan)變為(wei)零電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，使V1由(you)導通轉(zhuan)為(wei)關(guan)斷(duan)(duan)，從而(er)切斷(duan)(duan)了放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)回路，使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)無法(fa)再對(dui)負載(zai)(zai)進行(xing)(xing)放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，起到(dao)過(guo)放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)保(bao)護作(zuo)用。而(er)此時(shi)(shi)(shi)(shi)由(you)于(yu)V1自帶(dai)的(de)(de)體二極(ji)管VD1的(de)(de)存在，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)可以(yi)通過(guo)該二極(ji)管對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)進行(xing)(xing)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。由(you)于(yu)在過(guo)放(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)保(bao)護狀態(tai)下電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不能再降低(di)，因(yin)此要求保(bao)護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)消耗(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流極(ji)小，此時(shi)(shi)(shi)(shi)控(kong)制IC會(hui)(hui)進入低(di)功耗(hao)狀態(tai)，整個保(bao)護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路耗(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)會(hui)(hui)小于(yu)0.1μA。在控(kong)制IC檢(jian)測(ce)到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)低(di)于(yu)2.3V至發出(chu)關(guan)斷(duan)(duan)V1信號之間，也有一段延時(shi)(shi)(shi)(shi)時(shi)(shi)(shi)(shi)間，該延時(shi)(shi)(shi)(shi)時(shi)(shi)(shi)(shi)間的(de)(de)長短由(you)C3決定，通常設為(wei)100毫秒左右，以(yi)避免因(yin)干擾而(er)造成誤判斷(duan)(duan).