Design of high precision thermal resistance measurement circuit based on 3-wire
Zhou Hongping · Electronic Design Engineering · 2010
In this paper,an accurate method with constant voltage detection for precision measurement of 3-wire thermal resistance is presented.Unlike the 3-wire balance bridge,this method isn't affected by lead resistance.The paper designed the measurement circuit model as well as analyzed measunement to improve the measurement precision,and reduced the formula of digital calibration.In addition,a 3-wire thermal resistance input detection circuit was designed by using OP07 and 14-bit A/D ICL7135 converter.The results show that the measurement error is better than ±0.1 % for Pt100 thermal resistance with lead resistance is from 0 to 20Ω.