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Original question:

AM3358: Beaglebone Black schematics

Necessity of connecting to the NRESET_INOUT(WARMRSTn) pin

O.H
Mastermind 6340 points
Other Parts Discussed in Thread: TPS65217

Hi experts,

I am wondering about the role of U16 (SN74LVC1G07DCK) in the BBB diagram below.

Is it necessary to connect the PMIC_PGOD signal to the NRESET_INOUT(WARMRSTn) pin, I am thinking that only the PORZn pin input is needed.

I understand that it is made by BeagleBone, but it would be helpful to know.

Best regards,
O.H

  • 0
    TI__Mastermind 22110 points

    Hi O.H.,

    I'm not as familiar with AM335x specific operations requirements, but after looking at the datasheet it seems like connecting to NRESET_INOUT is optional. The U16 device serves to eliminate issues with a potential output glitch that could cause premature resets on external components connected to NRESET_INOUT.

    If you are not using the NRESET_INOUT pin at all and are simply leaving it floating. I do not think the U16 device connection is needed. There is no descriptive info in the AM335x datasheet for the NRESET_INOUT (WARMRSTn) that would suggest that this pin is required for operation. Most of the power sequencing and boot condition information is entirely related to the PORz pin (PWRONRSTn) pin which is directly connected to PGOOD.

    This User's Guide seems to have more information specifically on the NRESET_INOUT (WARMRSTn) functionality in Section 8.1.7.4:

    AM335x and AMIC110 Sitara Processors Technical Reference Manual (Rev. Q)

    I would recommend reaching out to the AM335x processor team if you need further detail about the processor requirements and potential errors.

    Regards,

    James

  • 0 in reply to James Steenbock
    Mastermind 6340 points

    Hi James,

    Thank you for your suppport. I understood.

    Figure 8-24. External Buffer for nRESETIN_OUT" is applied for this customer usage. Therefore, a buffer is likely to be required. We will contact you again if additional questions or problems arise.

    Best regards,
    O.H