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Original question:

ADS1298: ADS1298: Power consumtion

ADS1298: AVDD current realted to reset?

yonggang Yang
Prodigy 30 points
Part Number: ADS1298

Hi Guys,

     I have a board designed according the ADS1298 EVM circuit. I got the current of AVDD less than 1mA when add AVDD=3.3V,ASS=0V,DVDD=3.3V first time.

when i add the voltage above again the current of AVDD went to more than 10mA 。I didn't connect RESET pin with high or low. I found the current of AVDD typical value  is about 3mA.

I found the reset pin pull high in EVM circuit.Does the reset pin must be high when power on? 

Does the reset pin is floated will cause the AVDD current rise to 10mA?

Thanks!

  • 0
    TI__Mastermind 19815 points

    Hi,

    I don't quite understand the question, could you explain a bit more clear?

    ----------------------

    "I got the current of AVDD less than 1mA when add AVDD=3.3V,ASS=0V,DVDD=3.3V first time."    What do you mean first time?

    " add the voltage above again the current of AVDD went to more than 10mA 。"    What do you mean by add the voltage? and above again?

    "I didn't connect RESET pin with high or low"    /RESET pin should not be floating; floating RESET may cause ADS1298 unstable, please take a look of datasheet and EVM user guide schematic to see how you should treat the reset pin.

    Thanks

  • 0 in reply to ChienChun Yang
    Prodigy 30 points

    Hi ChienChun,

    Thanks for your reply.

    "I got the current of AVDD less than 1mA when add AVDD=3.3V,ASS=0V,DVDD=3.3V first time."    What do you mean first time?-----The first time to power on the ADS1298.

    " add the voltage above again the current of AVDD went to more than 10mA ."    What do you mean by add the voltage? and above again?----The second power on with AAVDD=3.3V,ASS=0V,DVDD=3.3V.

    And here is the schematic and i dont't connect digital singals such as RESET and SPI to MCU.

    And I think it is nessary to measure the  power ramp time of  AVDD tomorrow if any peak voltage out of the spec.

    Thanks a lot!

  • 0 in reply to yonggang Yang
    TI__Mastermind 19815 points

    Hi,

    It's suggested to get an ADS1298 Evaluation kit/board(EVM) to verify and validate with customer PCBA.

    --------------

    What is the AVDD – AVSS  voltage?

    When you mention more than 10mA? What exactly is it?  

    Thanks

  • 0 in reply to ChienChun Yang
    Prodigy 30 points

    There are some different between schematic that i posted to my PCBA.I changed the PCBA  AVDD to 3.3V, and connect the AVSS to DGND together ,so AVDD-AVSS=3.3V. And the current of AVDD is 15mA to 20mA.

  • 0 in reply to yonggang Yang
    TI__Mastermind 19815 points

    Hi,

     /RESET pin should not be floating; floating RESET may cause ADS1298 unstable, please take a look of datasheet and EVM user guide schematic to see how you should treat the reset pin.

    -----------------------------------------------

    If you are using Unipolar power supply,

    please take a look of datasheet 

    11.2 Connecting to Unipolar (3 V or 1.8 V) Supplies

    and

    11.1 Power-Up Sequencing

    -------------------------------------------------------------------
    It's suggested to get an ADS1298 Evaluation kit/board(EVM) to verify and validate with customer PCBA.

    Thanks