【摘要】：隨著以手機、平板電腦為代表的便攜式電子產(chǎn)品的快速發(fā)展,以及對綠色能源技術(shù)的迫切需求,電源管理系統(tǒng)逐漸向集成化、模塊化、智能化發(fā)展。限流配電芯片作為電源管理芯片的一員,是實現(xiàn)多元化電源控制的重要組成部分。其主要功能是實現(xiàn)功率控制,對限流精度及配電效率均有較高要求。而受限于大電流檢測精度,目前限流配電芯片限流閾值漂移通常在15%以上。本論文通過分析傳統(tǒng)配電芯片架構(gòu),結(jié)合項目需求,開發(fā)一款高精度可調(diào)限流配電芯片。該芯片通過電荷泵產(chǎn)生高壓驅(qū)動N型功率管,以提升導(dǎo)電效率。設(shè)計高精度電流檢測電路,采用高響應(yīng)速度電路結(jié)構(gòu),并利用增益自舉技術(shù)提升電流檢測精度。同時結(jié)合溫度系數(shù)補償技術(shù),以抑制限流閾值隨溫度及負載的漂移。設(shè)計高壓誤差放大器,構(gòu)成限流調(diào)節(jié)環(huán)路,實現(xiàn)恒流限流。同時利用誤差放大器可控的輸出擺率,實現(xiàn)“軟啟動”功能,防止功率管過快開啟產(chǎn)生涌浪電流。利用斬波技術(shù),設(shè)計帶失調(diào)校正功能帶隙基準源,有效抑制了由運放失調(diào)引起的基準電壓偏移。芯片可通過外接電阻設(shè)置兩個獨立限流閾值,并可通過限流閾值選擇端ILIM_SEL,在芯片工作過程中對限流閾值進行切換,從而便于處理器對供電模式進行控制。另外,芯片還具有完整的過溫保護、欠壓鎖定、過流保護及異常狀態(tài)顯示功能。采用0.25μm BCD工藝進行芯片設(shè)計實現(xiàn)。芯片具有高限流精度,限流閾值隨溫度及負載漂移僅為8.7%。外接電阻調(diào)節(jié)限流閾值范圍由500 mA到2.5 A。導(dǎo)通2 A電流時芯片導(dǎo)通電阻僅為61.5 mΩ,配電效率達97.1%。通過斬波失調(diào)校正,蒙特卡羅仿真下芯片基準電壓3σ偏差范圍約為±7.5 mV。芯片具有雙重過溫保護機制:當(dāng)芯片處于限流模式,過溫閾值為135℃,非限流模式下過溫閾值為155℃,過溫解除遲滯溫度20℃。芯片輸入電源低于4.05 V時進入欠壓鎖定狀態(tài),鎖定解除電壓4.15 V�？焖龠^流保護響應(yīng)時間為1.6μs。
[Abstract]:With the rapid development of portable electronic products represented by mobile phones and tablets, as well as the urgent need for green energy technology, power management systems are gradually becoming integrated, modular and intelligent. As a member of power management chip, current-limiting distribution chip is an important part of multiple power supply control. Its main function is to realize power control, which requires high current limiting precision and distribution efficiency. At present, the current limiting threshold drift of current limiting distribution chip is above 15%, which is limited by high current detection precision. Based on the analysis of traditional distribution chip architecture and project requirements, a high precision adjustable current limiting distribution chip is developed in this paper. The chip generates a high-voltage drive N-type power tube through a charge pump to enhance conductivity. The high precision current detection circuit is designed. The structure of high response speed circuit is adopted, and the gain bootstrap technique is used to improve the accuracy of current detection. At the same time, the temperature coefficient compensation technique is used to restrain the drift of current limiting threshold with temperature and load. A high voltage error amplifier is designed to form a current limiting loop to realize constant current limiting. At the same time, the output swing rate controlled by the error amplifier is used to realize the function of "soft start" and to prevent the surge current generated by the excessive opening of the power transistor. A band gap reference source for band offset correction is designed by using chopper technique, which effectively restrains the reference voltage offset caused by the operational amplifier offset. The chip can set two independent current limiting threshold by external resistor, and can switch the current limiting threshold in the working process of the chip through the current limiting threshold selector ILIMSEL, which is convenient for the processor to control the power supply mode. In addition, the chip also has complete over-temperature protection, under-voltage locking, over-current protection and abnormal state display functions. The chip is designed and implemented by 0.25 渭 m BCD process. The chip has high current limiting precision and current limiting threshold is only 8.7 with temperature and load drift. The current limiting threshold ranges from 500 Ma to 2.5 A. When the current is 2 A, the on-resistance of the chip is only 61.5 m 惟, and the distribution efficiency is 97.1m 惟. By chopping offset correction, the bias range of the reference voltage 3 蟽 is about 鹵7.5 MV under Monte Carlo simulation. The chip has a double over-temperature protection mechanism: when the chip is in current limiting mode, the threshold of overtemperature is 135 鈩，

本文編號：2138214