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TMDXRM57LHDK Schematics - RM57 Schematic vs. Datasheets Inconsistencies

Michael Zaffuto
Prodigy 95 points
Other Parts Discussed in Thread: RM57L843, TMS570LC4357, TMDS570LS31HDK

TMDXRM57LHDK Schematics, page 10 of 29 Rev. B, shows a few connections that seem not not match RM57L843 or TMS570LC4357 datasheets.  (The schematics do match the actual pcb layout though).

Datasheets Indicate:

J14 - Core Logic Voltage 1.2V

V19 - AD2IN[24] Input

W18 - AD2IN[24] Input (Alternate)

Schematic Indicates:

J14 - VCCPLL2

V19 - VSSAD (grounded)

W18 - VSSAD (grounded)

Q1: Is there a clarification regarding J14, should be used as VCCPLL2?

Q2: Are V19 and W18 actually VSSAD ground, or are they grounded for A2D ground conversion reference?

Q3: Are the micros RM57L843 and TMS570LC4357 pin compatible regarding Power and etc? (Other than feature differences)

Thanks :)

  • 0
    Prodigy 95 points

    Update: I'm realizing that TMDXRM57LHDK is derived from TMDS570LS31HDK and as such, the pinout of TMS570LS31x used V19 and W18 as VSSAD.
    Not a problem for me to give up two AD2IN[24] pins for backwards compatibility.

    Still working on J14 though, TMS570LS31X datasheet also has it listed as Core Logic Voltage 1.2V

    I've looked through the datasheets from other TMS57 and RM48 type devices, and have not come across any that use J14 as VCCPLL2.

    If J14 is actually bonded to Core Logic, and P11 (VCCPLL1) and J14(VCCPLL2 ?) are tied together per schematic, then the PLL EMI noise from VCCPLL1 would be injected into the CORE_VCC plane nullifying the filtering that the feed-through EMI capacitor was intended to provide.

    I'll keep looking/cross referencing in meantime, otherwise a second feed-through EMI capacitor and bypass capacitors for J14 would be the safest option just in case J14 is actually CORE_VCC and not VCCPLL2.

  • 0 in reply to Michael Zaffuto
    TI__Mastermind 49120 points
    Michael,

    The J14 ball should be labeled as "VCC" and not "VCCPLL2". The schematic needs to be updated, as this gives the impression that the PLL2 has a dedicated supply terminal.

    Regards,
    Sunil
  • 0 in reply to Sunil Oak
    Prodigy 95 points
    Thank you Sunil for your reply, I will insure J14 is connected to CORE_VCC.
    The reference schematic used in the HDK's may be followed by other hardware designer's
    and may result in unintended EMI issue from VCCPLL if used as is.