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DS90UB949-Q1: What is not accessible when RX_5V isn't powered?

Andy Snawerdt
Intellectual 2290 points
Part Number: DS90UB949-Q1

Hi Team,

As the title asks, I'm trying to determine what all is not accessible if the RX_5V HDMI power isn't provided. The power-up timing diagram doesn't indicate a bring-up time required between a PDB toggle & when RX_5V needs to be alive:

Therefore my assumption is that the serializer can be enabled without requiring RX_5V to be present. However, given RX_5V powers the HDMI RX_PHY block, my assumption is that data will not be able to be sent through our device until RX_5V becomes present. Are there any other limitations to what can be configured while RX_5V is not present?

Regards,

Andy

  • 0
    TI__Mastermind 37080 points

    Hi Andy,

    I also have the same assumption. Without RX_5V, you will not able to transfer video data from the HMDI to the 949. Let me check the documentation. I will get back with you by Monday or Tuesday.

    Aaron

  • +1 in reply to Aaron Heng
    TI__Mastermind 37080 points

    Hi Andy,

    I investigated on RX_5V. Here is what I concluded. According to the pin description, the RX_5V is a 5V input pin, that does a 5V detect function. It has nothing to do with power the device, it’s simply a 5V input indicating that 5V is present. And yes data will not be able to be sent through the 949 because the PLL will not lock if RX_5V is low in figure 3.

    DDC_SDA/SCL are 5V open drain outputs and 5V inputs.

    The rising edge of RX_5V initiates PLL lock time tPLD.

    Therefore, if RX_5V is not powered / driven then no PLL lock, not operational, no data. Please refer to figure 3 of the datasheet.

    Hope this helps. Let me know if you have further questions.

    Aaron