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Original question:

ADS1246: The ADS1246 register write was unsuccessful

ADS1246: May you pls help check ADS1246 circuit?

Chen Bogey8
Mastermind 9990 points
Part Number: ADS1246
Other Parts Discussed in Thread: LM2662

Hi Sir 

May you pls help check ADS1246 circuit?

                              

  • 0
    TI__Guru** 113765 points

    Hi Chen,

    What sensor(s) is being connected?  Is this a differential measurement or single ended?  And what is the purpose of R2 and R53? In general the circuit appears to be ok, but any noise in the negative supply will become a direct part of the measurement as it is being used as the reference.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Mastermind 9990 points

    Hi Bob

    Is our application is ok?

    What sensor(s) is being connected?

    K-TYPE Thermocouple temperature line.

    And what is the purpose of R2 and R53?

    To reference Datasheet P.83/84

    negative supply will become a direct part of the measurement as it is being used as the reference.

    The power from LM2662.pls refer attached file.

  • 0 in reply to Chen Bogey8
    TI__Guru** 113765 points

    Hi Chen,

    R2 and R53 should be the same value so that the TC is centered within the analog supply so that the proper common-mode is maintained for the ADS1246.  Also, R53 should connect to AVSS and not AGND when using bipolar analog supplies. 

    I would highly recommend that you not connect the LM2662 input voltage to the output of the U7 shunt regulator.  Current will be limited by R5 which may be required by U10.  The input voltage of U10 should be provided by the same connection point as U3 (unless this voltage is greater than 5.5V which then in this case connect to the output of U3).

    How will the cold-junction of the TC be measured?

    Best regards,

    Bob B