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ADS4149: SEN reference

Harley Cumming
Prodigy 70 points
Part Number: ADS4149
Other Parts Discussed in Thread: DAC5672,

Hi All,

The datasheet states that SEN has a 180 kOhm internal pull-up resistor to AVDD (Page 10). Is this pin referenced to DRGND or AGND?

Thanks!

  • 0
    TI__Expert 4880 points
    Harley,

    I forwarded your question to a device expert. He should get with you shortly.

    Thanks

    Yusuf
  • 0
    TI__Guru* 91947 points

    Harley,

    This pin is referenced only to AVDD. We are not sure what you are asking.

    Regards,

    Jim

  • 0 in reply to jim s
    Prodigy 70 points

    Hi Jim,

    I am trying to use this device on a board with a DAC5672. I am contemplating splitting the ground plane into DRGND and AGND with a star connection by the DAC. If I do this I do not want to inadvertently introduce a ground loop so I am trying to understand what the digital pins are referenced to. If I understand correctly, the output data pins are referenced to DRGND and DRVDD. SEN seems like a digital pin to me but has a pull-up to AVDD.

    Does that mean I should drive SEN with a signal referenced between AVDD and AGND or DRVDD and DRGND? And likewise, should I drive OE, CLKP, CLKN, RESET, SCLK, and SDATA the same?

    Please let me know if I can clarify more.

    Thanks!

  • 0 in reply to Harley Cumming
    TI__Guru* 91947 points

    Harley,

    I would recommend you use one GND plane for your board. For the ADC discrete signals, I would suggest to drive the signals with a device that supports either 1.8V or 3.3V CMOS logic levels. Using only one GND plane will be easier to route and will probably give you the best performance. See the attached document for more info regarding this. I also attached the ADS4149EVM schematic as well for reference. On this board, a FTDI device is providing the SPI interface with no problems.

    Regards,

    Jim

    ADS41XX-58B18-SCH_A.pdf8510.CMOS Schematic and Layout tips.ppt