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AM5K2E02 bulk decoupling recommendation

Brad Griffis
Guru*** 125430 points
Other Parts Discussed in Thread: AM5K2E02

This question pertains to the Hardware Design Guide for KeyStone II Devices Application Report.  In particular, this is with regard to Table 3 Bulk, Intermediate, and Bypass Capacitor Recommendations (Absolute Minimums).  This application report applies to all Keystone 2 devices, though I expect that CVDD likely scales proportionally to the number of cores.  Can you provide any guidance on what would be an appropriate selection of capacitors for an AM5K2E02 device?  I think most rails can simply be looked up in the table, though for CVDD in particular (maybe CVDD1?) I would appreciate more specific guidance.

Thanks!
Brad

  • 0
    TI__Mastermind 43660 points
    Hello Brad,

    The values listed in the hardware design guide are based on a board we developed to characterize the high speed interfaces for the K2K and K2H devices. That board was designed to handle some of our worst case scenarios, so the capacitor values were provided as a template as a solution for customers that have not performed their own PDN analysis.

    There is no guideline available for K2E devices in specific. However you could use K2E EVM design as a reference for optimal capacitance requirement. The selection of capacitors for a design must be part of a power distribution network (PDN) analysis. Power supply design, layout, board material, capacitor selection and capacitor positioning all contribute to the impedance profile of your board across the range of frequencies.

    Anyhow i will check with the internal team if they have any guideline for capacitor requirement for K2E devices and update you.

    Regards,
    Senthil
  • 0 in reply to Senthilkumar Srinivasan
    TI__Mastermind 43660 points

    Hello Brad,

    There is no specific capacitor requirement guideline available for K2E devices.

    The Hardware Design Guide provides a example list of capacitors.  This is an example from K2H.  However the previous sections provide generic guidance. Specifically, 2.4.1 shows the equations for bulk capacitor calculation. These equations could be used for finding the capacitor requirement for K2E devices.

    Regards,

    Senthil

  • 0 in reply to Senthilkumar Srinivasan
    TI__Guru*** 125430 points
    I see a calculation pertaining to max ESR, though not to the amount of bulk capacitance. Given that the initial design was for 8 DSPs and 4 Cortex A15s, I'm going to use 2 of the 1500 uF caps instead of the 8 recommended since this particular design will be AM5K2E02 with only two A15's.