多路电阻式温度传感器超温巡检电路应用中的问题和分析

Problems and Analysis of Over Temperature Polling Circuit of Multi-resistance Sensor

某产品中的多路温度超温巡检电路采用了低成本的模数混合设计,其中模拟电路用于完成电阻式温度传感器电阻(温度)值的测量及判断,数字电路用于完成10路电阻式温度传感器的切换;该电路的巡检周期为2s(5%),报警的最小电阻值为1050Ω;在最初的设计中由于考虑欠周,在长期使用中该电路出现了器件易损坏和误报警等问题;通过对原设计进行改进,提高了产品的稳定性和可靠性,并提出了该类电路设计时应该注意的事项。

The multi--resistance superheat polling circuit in one product is a low cost design. It is composed of digital and analogue circuit. The analogue circuit is used to test the temperature and judge if to make alert or not. The digital circuit is used to change the 10 channels of resistance temperature sensor in turn. The patrol circle of the circuit is 2s （5%）, the minimum resistance to alert is 1050. Many problems exist in the original circuit because of unreasonable design. Many problems take place in the long time of application such as the amplifier is easy to damage and the circuit make wrong alert etc. By the way of improving the original design, the product＇ s stability and reliability is enhanced. In the end, what should be noticed in the designing of this kind of circuit is proposed.