PSoC5LP DelSig problem with input range +/-Vref/4, /8, /16 | Cypress Semiconductor
PSoC5LP DelSig problem with input range +/-Vref/4, /8, /16
I am trying to use Delta Sigma ADC with 16bit resolution in differential mode. I created 4 configurations, which differ only in input range (image for CFG0):
- CFG0 - +/-1.024V
- CFG1 - +/-0.256V
- CFG2 - +/-0.128V
- CFG3 - +/-0.064V
I am using 10 Ohm resistor as a shunt to measure current going through a 10kOhm resistor at 3.3V. In topdesign I just connected two analog input pins to inputs of ADC.
If I use configuration 0 (input range +/-1.024V), I get values that are similar to those that I measure with my multimeter, around 3.15mV. However, if I use any of the other 3 configurations, measured voltage is around 1.75mV.
I have also tried to modify the CFG0 to use different input ranges, but I get same results. Also, if I use input range +/-0.512V, I get expected results (~3.15mV). So the problem appears when I use input range +/-0.256V, +/-0.128V and +/-0.064V.
Am I doing something wrong? Are there any additional settings that need to be configured?