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66AK2L06: unused functions and device pins open or strapped

bryan ogilvie
Intellectual 350 points
Part Number: 66AK2L06


Hello again, our 66AK2L06 design will not be using quite a few of the device functions.  I have read a lot of the documents for the KeystoneII devices.  Most of the questions get answered, however I have not found advice on what to do with device pins of the function is unused: Examples USB3.0, DDR3, and EMIF.  Can I leave the all the pins associated with these interface not connected if the functions are unused??

  • 0
    TI__Guru**** 161600 points

    Hi,

    Examples USB3.0, DDR3, and EMIF.  Can I leave the all the pins associated with these interface not connected if the functions are unused??

    This is explained in the hardware design guide ():

     - For USB see Section 6.13.7 Unused USB signals:

         "If the USB interface is not used, all of the USB signals may be left unconnected. If your KeyStone II device has multiple USB interfaces and only one is used, the remaining USB signals my be left unconnected."

     - For DDR3 - Section 6.8.3 Unused DDR3 Pin Requirement:

           "If the DDR3 peripheral is disabled, all interface signals (including reference clocks) can be left floating and the input buffers are powered down.

             All unused DDR3 address pins must be left floating. All unused error correction pins must also be left floating. All remaining control lines must also be left floating when unused. Unused byte lanes must be properly disabled in the appropriate MMR.

             f the DDR3 interface is not required, the DDR3 PLL supply (AVDDA2) must still be connected and the ferrite bead installed to minimize noise.

             If unused, the primary DDR3 clock input must be configured as indicated in Section 3.3, Figure 15. Pull-up must be to CVDD core supply. The VREFSSTL pin must be connected to the VREF (0.75 V) supply regardless of whether the DDR3 interface is used or not used."

     -For EMIF, see 6.11.3 Unused EMIF16 Pin Requirements:

          "If the EMIF16 peripheral is not used, the EMIF16 inputs can be left unconnected.

    Internal pull-up and pull-down resistors are included on this interface so leakage will be minimal. If only a portion of the peripheral is used, data pins that are not used can be left floating.

    Note—The above recommendations are based on the peripheral being unused and no traces attached. If traces are attached to any of the peripheral input pins, added pull-up (to DVDD18) or pull-down (to VSS) resistors (4.7 kOhm) are needed."

    NOTE: Also check the Data Manual, if there are no other explicit recommendations for unused pins for a specific IP, then follow the above sections in Hardware Design Guide for Keystone II Devices.

    Best Regards,

    Yordan