Universal Resistance-to-Digital Converter

A universal resistance-to-digital converter based on the Universal Sensors and Transducers Interfacing integrated circuit (USTI) investigated and described at the first time. A three-point calibration technique for accurate resistance measurements in a wide resistive range has been implemented in a single integrated circuit that allows a direct resistance-to-digital conversion according to three popular serial interfaces RS232, SPI and I2C. At a minimum possible hardware configuration, the integrated circuit lets obtain the average relative error ± 0.47 % in the wide measuring range from 10 Ohm to 10 MOhm, and ± 0.01 % relative error at conditional splitting of the range of measurement into sub ranges with a choice of appropriate values of the reference resistor and charging-discharging capacitor. In addition, the designed integrated circuit can work with any resistance-to-time or resistance-to-frequency conditioning circuits and is suitable practically for any resistive sensors and transducers. In such cases, their outputs should be directly connected to any of two USTI’s channels for frequency-time measurements. The designed integrated circuit also has several addition advantages such as low cost, universality, small size (32-pad MLF 5x5x1 mm package) and high reliability.

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