CN3059是一種對單節磷酸鐵鋰電池進行恒流、恒壓充電的充電器IC。用該IC組成的充電器主要特點：充電電流可由一外設電阻RISET設定，最大充電電流可達1A；輸入電壓4～6V，可采用USB接口或4.5～6V輸出電壓（輸出電流1000～1500mA）的AC/DC適配器供電；充電器電路簡單、外圍元器件少、成本低；對過放電（電池電壓＜2.0V）的電池有小電流預充電模式；內部有功率器理電路，若芯片的結溫超過115℃時能自動降低充電電流作過熱保護，使用戶可設置較大的充電電流，以提高充電效率；有兩個LED分別作充電狀態指示及充電結束指示；有輸入電壓過低（＜3.61V）時的輸出鎖存功能、自動再充電功能、電池溫度監測功能；采用小尺寸、散熱增強性的10引腳DFN封裝；充電溫度范圍0～45℃或0～65℃(由充電電池參數決定)。
CN3059是磷酸鐵鋰電池的專用充電器IC，但它還有一個獨特的特點：外設一個電阻RVSET，它可以增加恒壓充電的輸出電壓。利用這個獨特的特點，可以組成簡易的3節鎳氫電池充電器及4V鉛酸電池充電器或鋰離子電池充電器。
由CN3059組成的充電器適合充 0.5～4Ah的磷酸鐵鋰電池。其應用領域：礦燈、LED應急燈、警示燈；車模、船模、航模及電動玩具；在照相機中，用3.2V磷酸鐵鋰電池替代一次性3V鋰電池（型號為CR123A），其外廓尺寸相同；通信裝置；小型醫療儀器及野外測試儀器；小型電動工具等。另外，可采用CN3059組成充3節鎳氫電池及4V鉛酸(suan)電池的充電器等。

封裝、引腳排列(lie)及功能
CN3059采用散熱增強型10引腳小尺寸DFN封裝，其引腳排列如圖1所示，各引腳功能如表1所示。

圖1 CN3059引腳圖

主要參數
CN3059的極限參數：各引腳的電壓范圍為-0.3～6.5V；BAT引腳與GND短路時間可連續；靜電擊穿電壓為2kV；最高結溫為150℃；焊接溫度為300℃（10s）。
CN3059的電(dian)(dian)氣參數：電(dian)(dian)源(yuan)輸入電(dian)(dian)壓(ya)(ya)(ya)(ya)范圍為(wei)(wei)(wei)4～6V；靜(jing)態電(dian)(dian)流典型值(zhi)為(wei)(wei)(wei)650μA；低(di)壓(ya)(ya)(ya)(ya)鎖存電(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)VIN≤3.61V；預存電(dian)(dian)閾(yu)(yu)(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)是(shi)電(dian)(dian)池電(dian)(dian)壓(ya)(ya)(ya)(ya)小于2.05V；恒壓(ya)(ya)(ya)(ya)充電(dian)(dian)電(dian)(dian)壓(ya)(ya)(ya)(ya)3.6V；充電(dian)(dian)結束閾(yu)(yu)(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)（ISET端(duan)(duan)電(dian)(dian)壓(ya)(ya)(ya)(ya)）為(wei)(wei)(wei)0.22V；睡(shui)眠(mian)模(mo)式閾(yu)(yu)(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)VIN－VBAT≤20mV；睡(shui)眠(mian)模(mo)式解除閾(yu)(yu)(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)VIN－VBAT≥50mV；TEMP端(duan)(duan)高溫閾(yu)(yu)(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)80%VIN，低(di)溫閾(yu)(yu)(yu)值(zhi)電(dian)(dian)壓(ya)(ya)(ya)(ya)為(wei)(wei)(wei)48% VIN。

典型應用電路
采用CN3059組成磷酸鐵鋰電池充電器電路與由CN3056組成的鋰離子充電器電路相比，前者有兩個突出的優點：①精確檢測充電電池的電壓，充電電池的終止充電電壓控制得更精確，使電池充的更滿；②采用在FB端與電池正極之間加接一個電阻RVSET，使充電器除能充磷酸鐵鋰電池外，也可簡單地組成充鉛酸電池及鎳氫電池，擴展了充電器功能。下面分別介紹這2種典型應用電路。
1、充磷酸鐵鋰電池電路
充電(dian)(dian)電(dian)(dian)池(chi)型(xing)號為26650，容(rong)量為2800mAH，采(cai)用1000mA恒流電(dian)(dian)充電(dian)(dian)（其充電(dian)(dian)率(lv)約0.36C），充電(dian)(dian)器電(dian)(dian)路如圖2所示。

                                                                                                              圖2 磷酸鐵鋰(li)電(dian)池充電(dian)電(dian)路

充電器采用輸出直流電壓5V、輸出電流1500mA的AC/DC適配器作電源。用紅色LED作充電狀態指示燈，用綠色LED作充電結束指示燈。設定恒流充電電流ICH=1000mA，則RISET為：
RISET=1800V/1A=1.8kΩ （1）
CIN(10μF)及COUT(10μF)是為保證充電器工作穩定的輸入及輸出電容，可采用多層陶瓷電容器（MLCC）。
這里重點介紹精確電池電壓檢測電路。圖3是一般電池電壓檢測電路，圖4是精確電池電壓檢測電路。圖3中，BAT端外接充電電池，內接由R1、R2組成的電阻分壓器，其中間點為輸入誤差放大器，根據充電電池的實際電壓來對電池進行預充電、恒流充電及恒壓充電。若在恒流充電時的充電電流為ICH、BAT端的電壓為VBAT，電池的電壓為V’BAT。若BAT端到電池正極之間的金屬連接線的電阻為△R，則ICH電流從BAT端到電池正極間的電壓降VDROP =ICH×△R，則VBAT=ICH×△R+V’BAT (V’BAT＜VBAT）。充電電流越大，則VBAT與V’BAT的差值越大。輸入到誤差放大器的電壓是VBAT的分壓而不是V’BAT的分壓，因此產生電池實際電壓的檢測誤差。
再看圖4電(dian)(dian)(dian)路，BAT端向電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)。另(ling)外(wai)，由電(dian)(dian)(dian)池(chi)正極(ji)加一條連接到FB端，將(jiang)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓通(tong)過R1、R2分壓器(qi)后(hou)輸入(ru)誤差放大(da)器(qi)。

圖(tu)3 一般(ban)電(dian)池(chi)電(dian)壓(ya)檢(jian)測電(dian)路

圖4 精確電池(chi)電壓檢測電路

粗看起來，FB端、電池正極端及BAT端是同電位的。但要注意的是從BAT端流到電池正極的電流是ICH，若連接線電阻為△R，其壓差VDROP=ICH×△R；而若從電池正極流入FB的電流是IFB，連接線電阻也為△R，則V’BAR－VFB的壓差為IFB×△R。因為ICH往往是0.xA～1A，而IFB≈3μA ，所以VBAT與V’BAT的壓差較大，而V’BAT與VFB之間的壓差甚小（VBAT＞V’BAT＞VFB），用VFB端反饋到誤差放大器的電壓與電池的實際電壓更接近，即檢測電池電壓更精確。這一種精確測量方法也稱為開爾文檢測法（KeLvin）。用這方法精確檢測電池電壓可使電池的終止充電電壓更精確，電池也沖的更滿。
2 、充4V鉛酸電池或3節鎳氫電池或鋰離子電池的電路
在FB端(duan)與電(dian)(dian)(dian)池(chi)正極之(zhi)間加(jia)一(yi)個RVSET電(dian)(dian)(dian)阻，可以(yi)調節恒壓充電(dian)(dian)(dian)的電(dian)(dian)(dian)壓這一(yi)特點，則(ze)除充磷酸(suan)鐵鋰(li)電(dian)(dian)(dian)池(chi)外，還可組成簡易4V鉛(qian)酸(suan)電(dian)(dian)(dian)池(chi)或3節鎳氫電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)器，電(dian)(dian)(dian)路如圖5所示(shi)。

圖5 鉛酸電(dian)池或(huo)鎳氫電(dian)池充電(dian)器電(dian)路

設定的終止充電電壓Vbat與RVSET的關系為：
Vbat（V）=3.6（V）+3.04×10-6（A）×RVSET（Ω）            （2）
由(you)于(yu)這種簡(jian)易充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器設定了終(zhong)止充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓，所以在(zai)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)(cheng)不(bu)會產生(sheng)過充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)情況，即充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)是(shi)(shi)安全的(de)(de)(de)(de)(de)。但由(you)于(yu)不(bu)同(tong)(tong)種類的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)有(you)各自(zi)的(de)(de)(de)(de)(de)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)程(cheng)(cheng)式及終(zhong)止充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)檢測方法，因此用CN3059組成的(de)(de)(de)(de)(de)簡(jian)易充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器在(zai)充(chong)滿程(cheng)(cheng)度上需要差一(yi)(yi)(yi)些。另外，在(zai)充(chong)3節(jie)鎳(nie)氫電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)時，由(you)于(yu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器沒(mei)有(you)每節(jie)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)均(jun)壓充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)路，所充(chong)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)應是(shi)(shi)同(tong)(tong)一(yi)(yi)(yi)種型號、同(tong)(tong)一(yi)(yi)(yi)公司生(sheng)產、同(tong)(tong)一(yi)(yi)(yi)組使用的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)，否則(ze)會造(zao)成由(you)于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)(de)內阻不(bu)同(tong)(tong)而產生(sheng)的(de)(de)(de)(de)(de)有(you)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)未充(chong)滿，有(you)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)已過充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)情況。不(bu)同(tong)(tong)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)(de)(de)RVSET值如表2所示。

圖6 3.2V磷酸鐵鋰電池及3.6V鋰離子電池充電器電路