一种低温漂的欠压保护电路的设计

Design of under-voltage protection with low temperature drift

针对DC—DC电源管理系统中所必须的欠压保护功能，提出一种随温度变化很小的欠压保护电路。该电路结构简单，不需要额外的带隙基准电路，同时也省去了电压比较器电路。电路特别考虑了温度特性，减小了温度对阂值电压和迟滞量的影响。采用0．5μmOKI工艺，运用Cadence和Hspice进行仿真。结果表明，当电源电压降低到3．6V时，输出高电平；当电压重新上升到3．79V时，输出低电平，迟滞量为0．19V。温度在-40℃～125℃变化时，翻转阈值电压和迟滞变化范围仅为30mV和70mV。在不同模型下，翻转阈值电压和迟滞变化范围均为30mV，满足电路的设计要求。

Under-voltage protection is important in DC-DC power management system. A short-voltage safeguard circuit, which changes less with the temperature, is presented in this paper. Compared with traditional short-voltage safeguard circuit, this circuit does not use additional bandgap reference and eomparator. To minimum the effect of temperature on circuit threshold voltage and hysteresis voltage, temperature character of devices has been considered in this design. The circuit is based on 0.5 μm OKI technology library, Cadence and Hspice software are used in circuit simulation. The simulation results show that the circuit has good performance. When the supply voltage is reduced to 3.6 V,the output becomes high. While,when it rises to 3.79 V,the out- put returns to a low level, the amount of hysteresis is 0.19 V.And with the temperature change in -40 ℃-125℃,the threshold and hysteresis are just 30 mV and 70 mV separately. In the different models, the range of threshold and hysteresis is just 30 inV. It satisfies the demand of the design.