66AK2G02: Wrap-up of questions about unused balls

Part Number: 66AK2G02

I've been posting questions about unused balls to e2e.ti.com/.../593504, but that thread has gotten too long and some loose ends are getting lost. So here is a wrap-up of the unanswered questions:

Yordan Kovachev said "However, I think there is something missing in the Data Manual (I am checking this with the documentation team).. The DQS & CLKOUT signals, which are differential signals should be tied (to ground or power supply) as described in the Schematic Checklist. I will check this further and elaborate here. " 

Yordan also said "For the differential clock out input, I think you need to follow 3.3 Unused Clock Inputs from Hardware design guide for keystone II devices (www.ti.com/.../sprabv0.pdf). See also 6.8.3 Unused DDR3 Pin Requirement from the same document. Again I will verify this and elaborate furhter. "

I asked "Can you clarify the requirement in Table 4-29 for balls T4 and T1?  They are required to have external pulldowns if unused. I am unsure about what "unused" means in this context because according to Table 4-1 they have only one function, UART0_RXD and UART0_TXD and are configured to muxmode 0 on reset release. They have pullups during reset, so it seems to me that the pullups would conflict with the required pulldowns and pull them to a mid-voltage state."

Any further word on these points?

Regards,

Debora

  • Hi Debora,

    I am unsure about what "unused" means in this context because according to Table 4-1 they have only one function, UART0_RXD and UART0_TXD and are configured to muxmode 0 on reset release

    Unused means that you don't need the UART0 connected on your board (you don't plan to use the uart in your application).
    In this case you must follow the recommendations in the Data Manual: Table 4-29. Unused Balls Specific Connection Requirements.  

    I've notified the hw designers of the K2G boards to confirm. 

    Best Regards,
    Yordan

     


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