Smart load cells based on switched-capacitors

Abstract

This paper describes a data acquisition solution using a singk chip RISC type microcontroller with very few other active and passive components around, taking advantage of lhe ratiometric functioning of lhe load cells. The ned for thermaly stable circuits and components is minimized through lhe use of lhe same amplification chain for both signal and reference, together with software calibration. The amplification and filtering is done through switched-capacitors techniques, controller by lhe microcontroller. This option allows lhe choice of lhe proper scale according to lhe platform, with periodical and automatical calibration. The analog-to-digital conversion is done using lhe single ramp approach controll~d by lhe microcontroler, which does alll lhe digital processing required as well as lhe serial communication with lhe external world. The paper also describes an example of software calibration of a multi-loadcell weighbridge, using OM single processing module per sensor.