Application Note 96

Sensors for pressure, load, temperature, acceleration and many other physical quantities often take the form of a Wheatstonebridge.Thesesensorscanbeextremelylinear and stable over time and temperature. However, most things in nature are only linear if you don't bend them too much.Inthecaseofaloadcell,Hooke'slawstatesthatthe strain in a material is proportional to the applied stress-- as long as the stress is nowhere near the material's yield point (the "point of no return" where the material is permanently deformed). The consequence is that a load cell based on a resistance strain gauge will have a very small electrical output--often only a few millivolts. In spite of this, instruments with 100,000 counts of resolu- tionandmorearepossible.ThisApplicationNotepresents some new approaches to high resolution measurement made possible by Linear Technology's family of 20- and 24-bit delta-sigma analog-to-digital converters.

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