【正文】 a major impact on this type of battery life. Photovoltaic, battery does not need regular maintenance, the correct charge and reasonable protection, can effectively extend battery life. Charging and protection IC is the separation of the occupied area and the peripheral circuit plexity. Currently, the market has not yet real, charged with the protection function is integrated on a single chip. For this problem, design a set of battery charging and protection functions in one IC is very necessary. design and considerationsThe system mainly includes two parts: the battery charger module and the protection module. Of great significance for the battery as standby power use of the occasion, It can ensure that the external power supply to the batterypowered, but also in the battery overcharge, overcurrent and an external power supply is disconnected the battery is to put the state to provide protection, the charge and protection rolled into one to make the circuit to simplify and reduce valuable product waste of resources. Figure 1 is a specific application of this Ic in the photovoltaic power generation system, but also the source of this design.accumulatorDC loadcontroller Discharge controllerChargecontrollersolar battery arrayFigure1 Photovoltaic circuit system block diagram Maintenancefree leadacid battery life is usually the cycle life and float life factors affecting the life of the battery charge rate, discharge rate, and float voltage. Some manufacturers said that if the overcharge protection circuit, the charging rate can be achieved even more than 2C (C is the rated capacity of the battery), battery manufacturers remend charging rate of C/20 ~ C/3. Battery voltage and temperature, the temperature is increased by 1 176。 the M0, M1, M2, R0 is the offset portion of the circuit to provide bias to the poststage circuit, the resistance, Ro, determine the circuit39。由于密封免維護鉛酸蓄電池具有密封好、無泄漏、無污染、免維護、價格低廉、供電可靠，在電池的整個壽命期間電壓穩(wěn)定且不需要維護等優(yōu)點，所以在各類需要不間斷供電的電子設(shè)備和便攜式儀器儀表中有著廣泛的應(yīng)用。這對于將蓄電池作為備用電源使用的場合具有重要意義，它既可以保證外部電源給蓄電池供電，又可以在蓄電池過充、過流以及外部電源斷開蓄電池處于過放狀態(tài)時提供保護，將充電和保護功能集于一身使得電路簡化，并且減少寶貴的而積資源浪費。但是由于不同的過放電電流對蓄電池的容量和壽命所產(chǎn)生的影響不盡相同，所以對蓄電池的過放電電流檢測也要分別對待。當(dāng)電池電壓或電流過低時，充電啟動比較器控制充電。 芯片內(nèi)部保護電路模塊框圖如圖3所示。圖4 保護電路應(yīng)用原理圖 由兩個充電與保護模塊結(jié)構(gòu)圖可將電路分為四部分:電源檢測電路(欠壓檢測電路)、偏置電路(取樣電路、基準(zhǔn)電路以及偏置電路)、比較器部分(包括過充電檢測比較器/過放電檢測比較器、過流檢測比較器和負載短路檢測電路)及邏輯控制部分。輸出為高，欠壓鎖定，起到了保護作用。由于此項目正在進行設(shè)計優(yōu)化階段，完整的仿真還不能達到要求，還需要對各個模塊電路進行優(yōu)化設(shè)計。在對電路做整體仿真時，主要觀察的是保護模塊對電池的充放電過程是否通過監(jiān)測Vdd電位和Vm電位而使芯片的CO端和DO端發(fā)生相應(yīng)的變化。圖5 欠壓檢測電路圖6 基準(zhǔn)電源電路圖 蓄電池的充電、電壓的穩(wěn)定尤為重要，欠壓、過壓保護是必不可少的，因此通過在芯片內(nèi)部集成過壓、欠壓保護電路來提高電源的可靠性和安全性。圖3 電池保護的系統(tǒng)框圖此模塊構(gòu)成的保護電路如圖4所示。這樣，當(dāng)電池短路或反接時，充電器只能以小電流充電，避免了因充電電流過大而損壞電池。當(dāng)電池處于過放電狀態(tài)的時間超過規(guī)定時間，則電池由于電池電壓過低可能無法再充電使用，從而使得電池壽命降低。圖1 光伏電路系統(tǒng)框圖 免維護鉛酸蓄電池的壽命通常為循環(huán)壽命和浮充壽命，影響蓄電池壽命的因素有充電速率、放電速率和浮充電壓。由此可見，充電方式對這類電池的使用壽命有著重大的影響。 R1 M14 is the feedback loop of the undervoltage signal。 C means that the battery float voltage. Ordinary charger for the best working condition at 25 176。C, single cell battery voltage drops 4 mV, negative temperature coefficient of 4 mV / 176。s operating point, the M0, M1, M2 form a current mirror。采用適當(dāng)?shù)母〕潆妷海谡Ｊ褂?防止過放、過充、過流)時，免維護鉛酸蓄電池的浮充壽命可達12~16年，如果浮充電壓偏差5%則使用壽命縮短1/2。圖1是此Ic在光伏發(fā)電系統(tǒng)中的具體應(yīng)用，也是此設(shè)計的來源。當(dāng)電池處于過充電狀態(tài)的時間較長，則會嚴(yán)重降低電池的容量，縮短電池的壽命。電器進入涓流充電狀態(tài)，當(dāng)驅(qū)動器截止時，該比較器還能輸出20 mA左右，進入涓流充電電流。該電路包括控制邏輯電路、取樣電路、過充電檢測電路、過放電檢測比較器、過電流檢測比較器、負載短路檢測電路、電平轉(zhuǎn)換電路和基準(zhǔn)電路(BGR)。文中主要介紹欠壓檢測電路設(shè)計(圖5) ，并給出帶隙基準(zhǔn)電路(圖6) 。本設(shè)計電路采用CSMC μm數(shù)字CMOS工藝對電路進行仿真分析。13