THERMAL COUPLING OF NTC CHIP THERMISTORS

A novel device called thermal coupling of NTC chip thermistors was made by combining two electrically isolated chip thermistors Th-1 and Th-2 having small dimensions (0603) and small power (1/10 W). The first thermistor Th1 (input thermistor) is self-heating at a constant supply voltage U - it generates heat while the second thermistor Th2 is passive (output thermistor) - it receives heat. Thermistors are electrically insulated, but thermally coupled. The temperature dependence of NTC chip thermistors R(T) was measured and exponential factor of thermistor resistance B was determined. After that, current I-1 of self-heating thermistor as a function of supply voltage U and using resistance R-1 of input thermistor was determined. The electrical resistance of output thermistor R-2 was measured by multimeter at the same time as the current of input thermistor. Using the Steinhart - Hart equation the temperature T-1 and T-2 of both thermistors were determined. The application of novel thermistor junction is expected in power microelectronics for electrical decoupling/thermal coupling of input to output slowly changeable signals.