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DP83848Q-Q1: Power consumption immediately after startup

Tomoaki Yoshida91
Genius 5255 points

Part Number: DP83848Q-Q1

Hi team,

While my customers are evaluating the DP83848Q, there is concern about the power consumption immediately after startup.

They are using multiple PHYs, but after powering on the PHY, they says that the power consumption varies depending on PHY.

When the power consumption is large, it is about 200 mW, so it looks like normal operation.

However, power consumption is high or low every time power is turned on.

If it is reset, it seems to be in normal operation.

Is it necessary to explicitly reset this device after power is turned on?

Will it happen that the state changes every time the power is turned on?

I am going to investigate in detail from now on, but I do not know what to investigate from.

Please let me know if you have any advice on how to do the survey.

Best regards,

Tomoaki Yoshida

  • 0
    TI__Mastermind 26320 points
    Hi Tomoaki-san,

    1. Can you share how much variation you see from each power cycle ?
    2. Is this only one board or across all boards ?

    Regards,
    Geet
  • 0 in reply to Geet Modi
    Genius 5255 points

    Hi Geet-san,

    Thank you for your support.

    Answer:

    1. If the power consumption is large, 200 mW and less, it seems to be 30 mW.

        Every time power is turned on again, it seems that the power consumption is large or small even in the same PHY.

        I wrote that it is a previous post and returning to normal operation when resetting, but this is a mistake.

       Even when resetting, the consumption current is generated randomly.

    2. The same thing happens on multiple boards.

    Best regards,

    Tomoaki Yoshida

  • 0 in reply to Tomoaki Yoshida91
    Genius 5255 points
    Hi Geet-san,

    I have an additional informaion.
    They are turning on the power without Ethernet connection.
    Does the PHY enter power down mode or go into operation mode when turning on the power in a situation where no cable is connected?

    Best regards,
    Tomoaki Yoshida
  • 0 in reply to Tomoaki Yoshida91
    TI__Mastermind 26320 points
    Hi Tomoaki-san,

    Please provide a clear table with scenario ( reset, power cycle, cable connected, not connected) and power consumption customer see on DP83848 to understand the issue.



    Regards,
    Geet
  • 0 in reply to Geet Modi
    Genius 5255 points
    Hi Geet-san,

    Thank you for your support.
    I mistakenly pressed the resolve my issue button.
    Please do not mind.

    Conditions for confirmation with this customer are as follows.

    The cable is not connected and communication is not done.
    It is just the state of turning on the board.

    1.After turning on the power, the power consumption before reset is 30 mW or 200 mW, which is randomly generated.
    2.After resetting, current consumption is 30 mW or 200 mW, which also occurs randomly.

    There is a mistake in resistance etc., and communication evaluation has not been reached.
    When power is turned on, the power consumption varies depending on the PHY, and power consumption changes when the power is turned on again, so they are investigating the cause before communication evaluation.
  • 0 in reply to Tomoaki Yoshida91
    TI__Mastermind 26320 points
    Hi Tamoaki-san,

    30 mW indicates Phy is in reset. Can you ask customer to check whether a clock is present on RX_CLK (I am assuming customer is using MII MAC interface on the design)

    Regards,
    Geet
  • 0 in reply to Geet Modi
    Genius 5255 points
    Hi Geet-san,

    Thank you for your support.
    Clocks were not output for both RX_CLK and CLK_OUT.
    Their system is operating at the default set by internal pull-up and pull-down resistors when the power is turned on, the external setting terminal is open.
    They can not read / write registers because MII communication can not work good.

    Is it possible that CLK_OUT will not be output while the device is operating normally?

    If the poewr up sequence is not followed, what kind of mode will the device be in?

    I think that DP83848 will start operation as long as it turn on the power, if it is starting with the default setting.


    Best regards,
    Tomoaki Yoshida
  • 0 in reply to Tomoaki Yoshida91
    TI__Mastermind 26320 points
    Hi,

    If device is configured for MII, Once the device is out of reset, RX_CLK shall always be present.

    Please look at Power, Input Clock circuitry and HW Straps are configured correctly.

    Regards,
    Geet
  • 0 in reply to Geet Modi
    Genius 5255 points

    Hi Geet-san,

    Thank you for your support.

    Since our customers are all default straps, they are going to work with MII operation.

    However, RX_CLK has not been observed.

    They will check the voltage of strap terminal at startup, power supply voltage etc. one by one.

    Best regards,

    Tomoaki Yoshida

  • 0 in reply to Tomoaki Yoshida91
    TI__Mastermind 26320 points
    Hi,

    I am closing this thread. In case of further assistance, please open new thread with reference to this thread.

    Regards,
    Geet