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DS90UB913A VDDIO current

Toshi
Expert 1780 points
My customer reported to me that a VDDIO current of DS90UB913A is very huge(=35.5mA) when it connected to DS90UB913A, (PCLK=83MHz, 10bit mode) Do you have any idea of reason why the huge VDDIO current ? Well, I've checked a VDDIO current of the device on the EVM, It is about 24mA(include 3LEDs current), This is no problem on the EVM. So I guess something worong was occured in the customer's sustem(Camera).
  • 0
    TI__Expert 5210 points
    Hi Toshi,

    What is the VDD_IO voltage that they are running at? Also, are you seeing 35.5 mA of current on the 913A or the 914A? I believe you are referring to the 913A, however It is unclear which device you are referring to in the first line of your post.

    Trace capacitance or external (lumped) capacitance contributes to an increase in current on the I/O. Please have the customer check their design for extra capacitance. Also, if you are seeing high current in regards to the VDD_IO on the 913A then I would check the input resistance of your customer's system. Our EVM has a 10kOhm pullup resistor attached to the 913A's LVCMOS inputs.

    -Sean
  • 0 in reply to Sean Thornton1
    Expert 1780 points

    Sean,

    Thank you very much for your advice.

    Well, we've checked the sysytem and found a problem on GPIO(O) and GPIO(1).

    The GPIO outputs are pull-downed by 0-ohm resister at the customer's system.

    When 913A connected to 914A,  the GPIO(O) and GPIO(1) outputs are active and

    output current increased to about 30mA.

    A Solution of the problem is to write 44H to register address: 0xod.

    I think it is a best solution for the problem, please let me know your opinion

    on the solution ?

  • 0 in reply to Toshi
    TI__Expert 5210 points
    Hi Toshi,

    What exact value are you writing to register 0x0D - 44? I am unsure what the "H" stands for in your post.

    In order to decrease the current on these GPO[0] and GPO[1] pins, you can increase the pulldown resistance on these pins so that they do not dissipate as much current. What is the pulldown resistance they they have used? Also, I would check to see if your customer's system would work without GPIO pulldown resistors - this way you can get rid of these components entirely. The default value output on GPO[0] and GPO[1] after power-on reset is "0" and these values will be maintained until the system explicitly changes them.

    -Sean