基于迟滞比较器的过热保护电路设计

为了防止芯片过热,提高芯片可靠性和稳定性,采用0.5μm CMOS工艺,设计了一种具有迟滞比较器的过热保护电路。由于采用了折叠式运放,使得比较器输入范围更大,灵敏度和迟滞性能更好。利用Cadence Spectre仿真工具对电路进行了仿真,结果表明电源电压为4.5～7 V时,过温保护阈值变化量极小,表现出输出信号对电源的良好抑制。当温度超过130℃时,输出信号翻转,芯片停止工作;温度降低至90℃时,芯片恢复工作。此电路可以通过调整特定管子的尺寸而控制两个阈值电压的大小,从而避免热振荡的发生。

Design on Thermal Shutdown Circuit with Hysteresis Comparator

To prevent overheating of the chip and improve the reliability and stability of the chip,using a 0.5 μm CMOS process,a thermal shutdown circuit with hysteresis comparator was designed.The structure of the folded cascade OPA was used in the comparator,so the comparator had a large input range as well as better hysteresis performance and temperature sensitivity.The circuits ware simulated by the cadence spectre,the results show that when the supply voltage is in the range of 4.5-7 V,the threshold voltage of over-temperature protection changes in a small amount,which means that the output signal has a good power supply rejection.When the temperature exceeds 130 ℃,the output signal turns over and the ship stops working.When the temperature falls down to 90 ℃,the chip works again.This circuit can control the magnitude of two threshold voltages by adjusting size of specific transistor,and because of this special function it avoids the thermal swing.