高精度反向阻断型限流电路设计  

Design of a high-precision reverse-blocking current limiting circuit

作　　者：唐威 孙梦凡 刘静 张洋洋 刘畅 单光宝 TANG Wei;SUN Mengfan;LIU Jing;ZHANG Yangyang;LIU Chang;SHAN Guangbao(School of Electronic Engineering,Xi’an University of Posts and Telecommunications,Xi’an 710121,China;School of Microelectronics,Xidian University,Xi’an 710071,China)

机构地区：[1]西安邮电大学电子工程学院,陕西西安710121 [2]西安电子科技大学微电子学院,陕西西安710071

出　　处：《西安邮电大学学报》2025年第1期74-81,共8页Journal of Xi’an University of Posts and Telecommunications

基　　金：国家自然科学基金项目(62134005)。

摘　　要：针对汽车安全充电应用需求,设计了一款具有反向阻断功能的高精度过流保护电路,采用0.18μm BCD工艺实现。电路中,功率管采用两个MOS管以“背靠背”方式连接,当输出端电压高于输入端电压时,其寄生体二极管能有效阻断反向电流通路。为提高采样精度,增加采样管的沟道长度,有效抑制其沟长调制效应;预放大电路保证了采样管与功率管的源端电位一致,输入级引入横向双极性晶体管,以降低输入噪声并提高运放增益,输出级采用双极性晶体管与MOS管组成的负反馈结构,有效抑制电流温漂,进一步提升限流精度;补偿电路通过在过流瞬间减小采样电流,限制功率管的通流能力,进一步保护内部电路免受过流冲击。测试结果表明,在-40℃条件下,输入电压为5.5 V,外接电阻20 kΩ时,限流精度最低为5.1%。A high-precision overcurrent protection circuit with reverse blocking functionality is designed to meet the requirements of automotive safe charging applications,and it is implemented using a 0.18μm BCD process.In the circuit,the power transistor consists of two MOSFETs connected in a“back-to-back”configuration,which can effectively block reverse currents through their parasitic body diodes when the output voltage exceeded the input voltage.To improve the sampling accuracy,the channel length of the sampling transistor is increased,which effectively suppresses the channel-length modulation effect.The pre-amplifier circuit ensures consistent source potentials between the sampling transistor and the power transistor.A lateral PNP transistor is introduced as the input stage to reduce input noise and enhance operational amplifier gain,while the output stage adopts a feedback structure comprising a bipolar transistor and a MOSFET to suppress the current thermal drift,and further improves the current limiting precision.The compensation circuit reduces the sampling current during overcurrent transients,limiting the conduction capability of the power transistor,and protecting the internal circuit from overcurrent damage.Testing results show that under the condition of-40℃,when the input voltage is 5.5 V and the external resistance is 20 kΩ,the current limiting accuracy reaches a minimum deviation of 5.1%.

关 键 词：反向阻断 高精度 限流电路 电流采样 限流值可调 

分 类 号：TN433[电子电信—微电子学与固体电子学]