Hi Sebastian If you have FSR(pin 14)=High you are using the device in Non-ECM (non-extended control mode) with configuration done by pin input only. In this case the CalDly/DES/SCSb pin should not be floating. If it is floating it may prevent a proper calibration from occurring. That may be the cause of what you are seeing. I would recommend setting the CalDly/DES/SCSb pin to logic high to select the longer Calibration Delay setting. In case making that change doesn't help, here are a few other things to look at: I would expect that the output data would toggle between two values that are within a few lsb of each other. If the output is changing only in larger steps I would make sure that all bits received by the FPGA are toggling. You could try applying an input signal that is close to full scale to see if some bits captured at the FPGA are always stuck at 0 or 1. Have you observed this on multiple boards, or have you only tested a single board so far? Is the device power consumption within the expected range listed in the datasheet? Once the part is powered up, if you initiate a calibration using the CAL input pin does the output code get closer to the expected values? Please confirm the calibration process is running by monitoring the CalRun output. If possible please attached your ADC related schematics in .pdf format. Best regards, Jim B
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