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AM3352: PORz during active mode

Kanae
Guru 10085 points
Part Number: AM3352

 

Hi Sitara support Team,

If AM335x is triggered by the external WDT during Active mode,
does it need the PORz on AM335x?

If it needs the PORz, the input voltage should be 0V.
If it does not need the PORz, the input voltage should be 0.5V
that is contained VIL of PWRONRSTn in the datasheet.
Is my understanding correct? 

In additional question, if it needs the PORz triggered by the external WDT,
is there any documentation contained the details?

Best regards,
Kanae

  • 0
    TI__Guru**** 393215 points
    Hi,

    I'm not sure that I understand your questions:
    "If AM335x is triggered by the external WDT during Active mode, does it need the PORz on AM335x?" Where is the WDT output connected?

    "If it needs the PORz, the input voltage should be 0V. If it does not need the PORz, the input voltage should be 0.5V that is contained VIL of PWRONRSTn in the datasheet. Is my understanding correct? " Can you explain in more detail what you mean?
  • 0 in reply to Biser Gatchev-XID
    Guru 10085 points

    Hi Biser,

    Thank you for your reply.
    I am sorry for my insufficient explanation in last post.
    I would like to explain it again make clear to you.

    If AM335x is triggered to reset completely by the external WDT during Active mode,
    does it need to connect to the PORz on AM335x via PMIC such as "figure-1"?
    Or can it be connect directly to PORz on AM335x such as "figure-2"?

    If it must connect to the PORz via PMIC, the PORz input voltage for the complete reset will be 0V by PMIC.
    If it can connect directly to the PORz, the PORz input voltage for the complete reset will be 0.5V
    that is the VIL max. value of PWRONRSTn in the datasheet.
    Is my understanding correct?

    Best regards,
    Kanae

  • 0 in reply to Kanae
    TI__Guru**** 393215 points
    I understand now. Figure 1 seems the better option, since when you reset the PMIC it will restart at default voltages. If you want to use Figure 2 it will be better to connect the WD reset to nRESET_INOUT, since this will only reset the processor (of course in this case the WD must be able to issue a low-level pulse, and not hold the line continuously low).
  • 0 in reply to Biser Gatchev-XID
    Guru 10085 points
    Hi Biser,
    Thank you for quick reply!

    I would like to make sure what you meant.

    1. If I want to reset completely, I have to connect "WDT IC" to PORz of AM3352 via PMIC.
    2. If I connect directly "WDT IC" to AM3352, it should connect to nRESET_INOUT of AM335x as "Warm reset".
    However "Warm reset" is not able to reset completely.

    Based on the above my understanding, I should choose the figure-1 connection for the complete reset.
    Is it correct?

    Best regards,
    Kanae
  • 0 in reply to Kanae
    TI__Guru**** 393215 points
    Yes, this is correct.