一种高精度过温保护电路的设计

摘要

设计了一种高精度的过温保护电路。利用晶体管基极和发射极的负温特性实现温度检测，通过将检测点电压和设定的电压相比较，检测是否过温。由于使用了一个高、低阈值可调的高精度滞回比较器，并且阈值电压点电压由与温度无关的带隙基准提供，因此实现较高的精度和可靠性。通过Cadence Spectre工具基于某公司0.35μm CMOS工艺进行了仿真验证。该设计具有20℃温度迟滞，热关断点为125℃，热开启点为105℃，在3~5.5 V的电压范围内，热关断点和热开启点温度最大漂移不超过0.4℃。%An high precision over-temperature protection(OTP)circuit is proposed. The temperature detection is achieved by using the negative temperature characteristic of base-emitter junction voltage. Then comparing the detected voltage and fixed voltage to determine whether over temperature or not. As a high accuracy hysteresis comparator with adjustable upper and lower threshold voltage is used and its threshold voltage is provided by a temperature independent bandgap reference, the precision and the stability are improved. Simulation using Cadence Spectre based on 0.35 μm CMOS process shows that the circuit can shut down the chip at 125 ℃ and open up at 105 ℃, and the hysteretic temperature range is 20 ℃. In the voltage range of 3~5.5 V, the maximum temperature drift of thermal shutdown point and thermal opening point are not more than 0.4 ℃.