How to further amplify the gain from a load cell? | Cypress Semiconductor
How to further amplify the gain from a load cell?
I have a load cell with four inputs/outputs: excitation +, signal +, signal -, and excitation -. Excitation + is connected to a 2.5V output and excitation - is connected to ground. Signal + and signal - are connected to two analog input pins on my PSoC 5LP. The load cells have a rating of 1.01 mV/V at 5000 pounds (50% load) and 2.03 at 10000 pounds (100% load). These readings were taken at 10V, however, and so we would expect that at 5000 pounds, it becomes about .25 mV/V, and at 10000 pounds, .5 mv/V. These are very tiny voltages.
For the PSoC, I am using a delta-sigma differential ADC to read the load cell. I am running it in multi-sample mode with 16 bits of resolution, the input range at -/+ 0.064V, buffer gain at 8, buffer mode of rail-to-rail, and using the internal 1.024 V volts as a reference.
When there is no load on the load cell, I am reading values of around 770, and when a calibrated 5000 pound weight is placed on the load cell (actually divided between four load cells, so around 1250 pounds each), I'm reading around 2880. I fear that this does not offer enough sensitivity for an algorithm that I am trying to use (peak detection).
I have experimented in using PGAs to amplify the signal, but it seems to have no effect, so I am concerned that I am using them incorrectly for differential mode. Can anyone provide me with some advice on how to amplify the signal to get more sensitive data? Thank you!