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AM335x EVM PWRONRSTn

Mark Norman
Prodigy 235 points

Hi,

I have been looking at the AM335x General Purpose EVM schematics for a guide as to how to connect the PWRONRSTn signal of the AM335x.

I noticed the EVM has connected PWRONRSTn to a 1.8V signal based on a Power Management IC output.  SPRS717C Table 3.7 specifies that the High Level Voltage threshold for the PWRONRSTn signal is 2V (VDDSHV6 = 3.3V).  This is obviously working ok for the EVM but I was wondering if acceptable to drive PWRONRSTn by a 1.8V signal in this case or have I missed something?

Kind Regards

Mark

  • 0
    Intellectual 460 points

    Hi Mark,

     

    PWRONRSTn levels depend on VDDSHV6. On EVM board VDDSHV6 is supplyed by PMIC VAUX2. I don't know what is the level of this power supply (I don't use the same PMIC). On Beagle Bone, VDDSHV6 is 3,3V and PWRONRSTn is directly dirven by PMIC where VIO supply is 3,3V. So both are possible.

    Take care of RTC_PWRONRSTn that is always at 1,8V levels.

     

    Regards

    Cyril

  • 0 in reply to Cyril BEGUET
    TI__Intellectual 2150 points

    For the GP EVM, there is an errata document out which shows PWRONRSTn needs to be supply with the same voltage rail as VDDSHV6.  Revision 1.2 of the GP EVM base board corrects this.

    Be sure in your design to use a 3.3V signal to PWRONRSTn if VDDSHV6 is powered at 3.3V.

  • 0 in reply to ddomke
    Prodigy 235 points

    Thanks for the information.  Do you happen to know where I could get a copy of the schematics for the Rev 1.2 hardware?

    Kind Regards

    Mark Norman