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AFE5851: Serial Interface SDOUT behavior

Thomas Mandal Nilsen
Prodigy 90 points

Part Number: AFE5851
Other Parts Discussed in Thread: AFE5808A

Hi,

How does the SDOUT signal behave when it is not sending data? Is it tristated from the AFE5851 side or pulled high/low? Is it ok to connect the SDOUT signal from several AFE5851s together and use /SEN to select the device?

  • 0
    TI__Genius 12025 points
    Hi Thomas,
    How are you?
    Thanks for using TI AFE5851 device.
    We will look into the detail for SDOUT pin and let you know soon.

    Thanks again!
    Have a nice day!

    Best regards,
    Chen
  • 0 in reply to Chen Kung
    TI__Genius 12025 points

    Hi Thomas,

    How are you?

    In order to let SDOUT output signal be read back,

    first, we need to set the register <REGISTER READOUT ENABLE> to be "1"

    by setting register as: Address=0x00, Data=0x0002

    Then we can start to use SDOUT pin (including /SEN, SCLK, SDATA) to read back the register data.

    Also if we don't want to use SDOUT output pin to read back,

    we need to set the register <REGISTER READOUT ENABLE> to be "0"

    by setting register as: Address=0x00, Data=0x0000

    Then SDOUT output pin would be set to low level all the time

    (because there is no data sending out.)

    also, note that: it won't be in tri-state.

    If you have AFE5851 EVM, please try this kind of test method to see the same result.

    We do have other device would set its SDOUT output pin in tri-state

    when we set <READOUT ENABLE>="0"

    such as for example: AFE5808A device can do it.

    Thank you very much!

    Best regards,

    Chen

  • 0 in reply to Chen Kung
    Prodigy 90 points

    Hi,

    I tested this using the EVM and I could observe the same behavior as you described. I measured around 22 ohm from SDOUT to GND, and it was independent of the state of REGISTER READOUT ENABLE. Will probably add a tristate buffer controlled by /SEN in order to use the same bus to control multiple parallel AFE5851.