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Are there any matters of concern about C6745 RSV4 pin unconnected?

j-breeze
Mastermind 7560 points

Hi Champs,

According to the latest C6745 datasheet SPRS377F, RSV4 pin description has changed as follows.

  - SPRS377F Page-6, Revision History

    Updated/Changed RSV4 DESCRIPTION from "...This pin may be tied high or low."
    to "...For proper device operation, this pin must be tied low or to CVDD."

However, one of my customers has already designed and shiped their board on which the RSV4 is unconnected
because the previous pin description was "may", not "must".

So, could you please let me know about any matters of concern about the RSV4 pin configuration that is unconnected?

Thanks in advance for your cooperation.

Regards,
j-breeze

  • 0
    TI__Mastermind 43660 points

    Hello J-Breeze,

    As specified in the datasheet, the RSV4 pin must be tied low or CVDD for proper device operation. If not doing so, you may expect reliability/functionality issues in any of the interface which relates to the RSV4 pin.

    Since i am not familiar about the device internal architecture, i will check with the concern team and confirm whether the RSV4 pin can be unconnected or not.

    Regards,

    Senthil

  • 0 in reply to Senthilkumar Srinivasan
    Mastermind 7560 points

    Hi Senthil,

    Thank you for your prompt reply.  I really need your help.
    Any information about the pin configuration would be appreciated.

    Regards,
    j-breeze

  • 0
    TI__Guru* 78475 points

    j-breeze

    The RSV4 in the QFP package is an input clock to a reserved logic , essentially it is equivalent to the RTC_XI in the C6747 (BGA package). 

    It is recommended that the pin is tied high or low as recommended in the datasheet, as you would typically do for an unused clock input pin 

    http://processors.wiki.ti.com/index.php/OMAP-L13x_/_C674x_/_AM1x_Schematic_Review_Checklist#RTC (RTC_XI)

    If it is not done, you might see noise riding in through the unconnected pin. 

    We leave the final judgement to your customer on whether this is something they should address or not, as per the datasheet recommendation.

    The feedback we got was to change it from "may" to "must" and more explicitly ensure that it is tied to a 1.2V supply not a 3.3V supply , therefore the change in the wording in the datasheet.

    Hope this helps.

    Regards

    Mukul 

  • 0 in reply to Mukul Bhatnagar
    Mastermind 7560 points

    Hi Mukul,

    Thank you for your prompt response as always.

    Regards,
    j-breeze