A novel smart interface for voltage-generating sensors

A novel low-cost smart interface for self-generating sensors, for instance thermopiles and thermocouples, has been presented. The proposed interface acts as an asynchronous converter for DC voltages or currents employing a relaxation oscillator which output is a period-modulated signal. A microcontroller is used to measure the output signal from the interface, process data and output the measured sensor signal. The system does not need the accurate A/D converter. Experimental results show that the interface is able to measure voltages in the range of 0~5 V, with an accuracy and resolution of ±64 ppm and 20 ppm, respectively. The measurement time is less than 100 ms