一种非对称欠压锁定电路设计

Design of an asymmetrical undervoltage lockout circuit

传统带隙基准结构的欠压锁定(UVLO)电路存在结构复杂、温漂特性差、功耗高等缺陷。为精准实现低温漂,提出了一种欠压锁定电路结构,该结构基于差分放大器的非对称性产生滞回电压,进而降低了阈值电压的温度敏感性,提高了阈值电压的精度。该欠压保护电路通过反馈控制法产生了上、下门限阈值电压,克服了单个阈值抗干扰能力差的缺点。电路基于0.18μm BCD工艺设计,仿真结果表明:当电源电压高于上门限阈值电压(V_(IH))2.2 V时,芯片系统正常工作;当电源电压低于下门限阈值电压2.01 V时,芯片系统被关断;在-55~+125℃温度范围内,该电路的滞回电压为0.19 V,V_(IH)温漂为0.01 V,滞回电压温漂为0.07 V,且该欠压锁定电路的功耗在3 V电源下为9.54μW。

The traditional undervoltage lockout(UVLO)circuit with bandgap reference structure has defects such as complex structure,poor temperature drift characteristics,high power consumption.To reduce temperature drift,an UVLO circuit structure was proposed,which generated a hysteresis voltage based on asymmetry of the differential amplifier.The UVLO thereby can reduce the temperature sensitivity and improve the accuracy of the threshold voltage.The UVLO circuit generated both upper and lower threshold voltage by feedback control method,which in turn overcame the shortcomings of a single threshold anti-interference ability.This circuit was designed based on the 0.18μm BCD process.The simulation results show that the chip system works normally when the power supply voltage is higher than the upper threshold voltage(V_(IH),2.2 V).When the power supply voltage is below the lower threshold voltage(2.01 V),the chip system is shut off.From-55℃to+125℃,the hysteresis voltage of the circuit is 0.19 V,the V_(IH) temperature drift is 0.01 V,the temperature drift of the hysteresis voltage is 0.07 V,and the power consumption of the UVLO circuit is 9.54μW at 3 V power supply.