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Proper state for AM571x Sysboot[15]

larry bernstein
Intellectual 280 points
Other Parts Discussed in Thread: AM5718, AM5728

Hi

Simple question..

The TRMs for  both the AM571x and AM572x  indicate  sysboot[15]  indicate  it needs to be  a pulled-up  to VDD   ( "H") .   Refer to table 33-4  in spruhz7b.pdf and  spruhz6f.pdf .

We are using also used the EVM schematics for a reference for our product design.. In the latest  revision of the design TI_AM572XEVM_REV_A3.pdf , it  shows sysboot[15]  being pulldown to VSS  ( "L") .  We do plan on have option in PCB design to pull-up  "H  or pull-down  "L" so we can  change but want an understanding of the proper setting.. Does it depend on SR, part #  in AM57xx family ?  Thank you

Larry

  • 0
    TI__Guru**** 393215 points
    Hi,

    See Table 33-4 in the AM572X TRM Rev. E.
  • 0 in reply to Biser Gatchev-XID
    Intellectual 280 points
    Looking more closely at this.. Section 18.4.6.1.1.1 Permanent PU/PD disabling (SR 2.0 only) gives the details. sysboot[15] for SR2.0 disables internal pull resistors of pads gpmc_a[27:19]
    Thanks..
  • 0 in reply to larry bernstein
    Intellectual 280 points
    Hi Biser, Revisiting sysboot[15] setting since the TRMs/errata for the AM5718 (SR2.0) and AM5728 (for SR2.0) seem to be conflicting. We plan to use both parts ( different products) and the designs using the eMMC ( MMC2).

    from: sprz429j.pdf ( Silicon errata for AM572x)

    i683: On SR2.x,the MMC2 DAT[x] terminals have internal weak pull-down resistors (PD) which are permanently
    disabled when SYSBOOT15=1 or enabled by default when SYSBOOT15=0. Refer to the TRM section “Permanent PU/PD disabling” for details.

    from sprz436a.pdf ( Silicon errata for AM571x)

    i683: On SR2.0 and SR1.0, the MMC2 DAT[x] terminals have internal weak pull-down resistors (PD) which are disabled by default when SYSBOOT15=0 or enabled by default when SYSBOOT15=1. Refer to the TRM section “Permanent PU/PD disabling” for details.

    Is the information above correct.. For AM572X ( SR2.x) we set SYSBOOT15=1 to disable internal PU/PD but with AM572X ( SR2.0) we set SYSBOOT15=0.

    Thank you

    Larry
  • 0 in reply to larry bernstein
    TI__Genius 15900 points
    Hi Larry,

    As documented in the errata, the polarity is different between the two devices. AM572x (SR2.0) uses SYSBOOT15=1 to disable internal PU/PD but AM571x (SR2.0) uses SYSBOOT15=0.

    Regards,
    Melissa