Two-wire system PT100 resistor and NTC resistor compatible temperature measuring circuit

Abstract

The invention provides a two-wire system PT100 resistor and an NTC resistor compatible temperature measuring circuit. A first resistor R1 and a third resistor R3 are connected in series, a second resistor R2 and a fourth resistor R4 are connected in series, and the above two series connection branches are connected to a reference voltage source VR and a ground respectively. One end of a two-wire system PT100 resistor or an NTC resistor is connected between the first resistor R1 and the third resistor R3, and the other end is grounded. The inverting input end 2 of an operational amplifier K1A is connected between the second resistor R2 and the fourth resistor R4 through a fifth resistor R5. The noninverting input end 3 pin of the operational amplifier K1A is connected between the first resistor R1 and the third resistor R3 through a sixth resistor R6. One end of an eighth resistor R8 is connected to the noninverting input end 3 pin of the operational amplifier K1A, and the other end is grounded. One end of a seventh resistor R7 is connected to the inverting input end 2 pin of the operational amplifier K1A, and the other end is connected to the output end 1 pin of the operational amplifier K1A. The noninverting input end 5 pin of an operational amplifier K1B is connected between the first resistor R1 and the third resistor R3 through a ninth resistor R9. The inverting input end 6 pin of the operational amplifier K1B is connected to the output end 7 pin of the operational amplifier K1B.

Description

technical field [0001] The invention relates to a temperature measuring circuit. Background technique [0002] PT100 resistance sensor is a temperature sensor whose resistance value changes with temperature. It has the advantages of good stability, high precision, and easy installation. It is a temperature sensor commonly used in industrial production processes. NTC resistance sensor, also known as negative temperature coefficient thermistor, is a kind of sensor resistance whose resistance value decreases with the increase of temperature. It has the advantages of long life, high precision, wide resistance range and diversified packaging. In the existing measurement circuit, the common PT100 resistance temperature measurement circuit is a constant current source type, and the generation circuit of the constant current source is relatively complicated and has low precision, which is not good for the temperature sampling accuracy; The detection method is simple, but it can onl...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to overcome the shortcomings of the existing PT100 resistance and NTC resistance temperature measurement circuit with complex structure and poor compatibility, and propose a two-wire PT100 resistance and NTC resistance temperature measurement circuit compatible

Images