Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

  • State Resolved
  • Locked Locked
  • Replies 7 replies
  • Subscribers 46 subscribers
  • Views 240 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS7950: Power-down state supply current

Liu Yang
Expert 6245 points
Part Number: ADS7950

Hi Team,

I want to use the ADS7950 in a battery powered device and wanted to clarify some information in the datasheet. The datasheet specifies a "Power-down state supply current" of 1uA. I want to clarify, is this the total power down current for both the analog and digital supply? As there are two power rails, I want to make sure the total current draw in sleep mode is low enough for my application.

Best Regards,

Tom Liu

  • 0
    TI__Mastermind 21987 points

    Tom,

    I believe that the current refers to the analog supply.  The digital supply current is primarily from the switched current from digital communications and should drop to a very low value when communications has stopped.  We will measure this to confirm.  This may take a few days.

    Art

  • 0 in reply to Art Kay
    TI__Expert 6245 points

    Hi Art,

    Thank you for that, we would greatly appreciate this measurement to confirm the consumption.

    In the meantime, can I clarify that the analog +VA supply must always be on when the digital +VBD supply is on?

    i.e. the analog section cannot be powered down when the digital supply is on?

    This is what I have interpreted from page 51 of the datasheet.

    Tom Liu

  • 0 in reply to Liu Yang
    TI__Mastermind 21987 points

    Tom, We are measuring it today.  Art 

  • 0 in reply to Art Kay
    TI__Expert 6245 points

    Hi Art,

    Is there any update for this case?

    Best Regards,

    Tom Liu

  • +1 in reply to Liu Yang
    TI__Mastermind 21987 points

    Liu,

    Sorry for the delay.  We had a holiday at the end of last week.  We measured the device to clarify the data sheet.  Below are the results.  Let me know if you have further questions.

    The 1uA is the analog supply (+VA).  Under static conditions, VA is drawing 1.09mA and I see it going to about 100nA in power down. The digital supply VB, is dynamic.  When static, it only draws 3.7uA.  It goes higher when you are actually converting data and using the SCLK, DOUT, etc. We don’t see any issues with power sequencing.

    Best regards,

    Art

  • 0 in reply to Art Kay
    TI__Expert 6245 points

    Hi Art,

    Thank you very much for getting back to me with those measurements. That helps a clarify the info a lot.

    My question around the power supplies is regarding page 51 in the datasheet. It states that the analog supply must always be greater than or equal to the digital supply. Does this mean that the analog supply cannot be turned off when the digital is on?

    Or does it not matter whether one supply is on or off?

    Best Regards,

    Tom Liu

  • +1 in reply to Liu Yang
    TI__Mastermind 21987 points

    For normal operation the supply must be turned on.  Turning off the analog supply will not damage the device or cause excessive current to flow.  You just cannot operate the device in this mode.

    Art