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ADS6145: Output data fluctuate 11 bits when input connects to VCOM

Part Number: ADS6145

Hi Team,

ADS6145 INP and INM are connected the VCOM, the schematic is as below:

The max and min output data error reaches 11 (8180~8191) which is larger than the datasheet, there are 22,000 samples in the picture. Is it caused by the clock? Could you please help advise if there is any way to minimize the error between max and min data? Thanks! 

Best Regards!

Hao

  • Hao,

    Do you have something else connected to the analog input other than the VCM? Try another test using an external VCM from a clean supply. There could be noise getting on the VCM signal from your board. Try filtering the clock. Does slowing down the clock help? Figure 25 shows the output should be 8211 with the inputs tied to VCM. It appears you have some additional offset coming in.

    Regards,

    Jim