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Im having difficulty reducing the code spread on a simple DC voltage measurement using the Delta Sigma ADC on the PSOC 5 CY8C5588AXI-060 my simple test is outputting the converted codes via UART to my PC to examine the results. DC Voltage measurements are yielding code values with spreads from 50-200 codes!
I have tried passing the results through an FIR Filter, as well as using an external voltage reference and external clock source. I have even tried to use a Bypass decoupling capacitor on the internal voltage reference as the data sheet said this may help. The code spread improves slightly when the FIR filter is used:
My main issue is that i have no benchmark to compare against! How low is the ADC code spread actually capable of going on a simple measurement such as this? is there an optimal configuration for reducing this?
Im using the Cypress CY8CKIT-001 with the PSOC 5 for the measurement.
To Supply the 1.2 V to the input of the ADC, im actually using an Audio Precision DCX-127. I use this for supplying both the ADC input votage, as well as an external reference voltage of 1.024. This is the most accurate and stable voltage source i have available to me.
I've attached a graph of my best possible test data so far and the configuration is as follows: