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TLA2021: AIN1 pin unused

Shuji Ishiwata
Mastermind 6335 points
Part Number: TLA2021
Other Parts Discussed in Thread: TLA2022

Hi all,

I have a question on TLA2021.

In the data sheet pin function (1), Unused pins may be connected to GND or open.
  "Float unused analog inputs, or tie unused analog inputs to GND."

In the data sheet p.22, AIN1 is connected to GND when used as a single. There is a description.
  "To measure single-ended signals with the TLA2021 and TLA2022, connect AIN1 to GND externally."

If it is single, must it be connected to GND?

Does the TLA2021 have a built-in MUX?
If built-in MUX, is AIN1 connected to GND inside the IC?

I do not know the inside of TLA2021 IC, so it would be helpful if you could give us a comment.


Best Regards,
Ishiwata

  • 0
    TI__Guru* 93725 points

    Ishiwata-san,


    If you are using the TLA2021 as a single-ended ADC, you would tie AIN1 to GND outside the device. There is no internal connection to ground that can be used for this device. It might be easier to explain with the register settings. From the datasheet you can see the multiplexer settings from the register table:



    Here it says that in the TLA2021 and TLA2022 these bits are always set to 000. So you wouldn't be able to set the inputs to ground internally. For these devices, there are no unused pins.


    Joseph Wu

  • 0 in reply to Joseph Wu
    Mastermind 6335 points


    Joseph-san,


    Thank you for your support.
    I understand.


    Best Regards,
    Ishiwata