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AM4372: Inquiry about power

Shuhei Goto
Expert 5350 points
Part Number: AM4372


Hi team,

I have questions regarding the AM4372 power pins and power-down sequence.

  1. In the datasheet section [5.12.1.1 Power Supply Slew Rate Requirement], what specifically are the "internal ESD protection devices" mentioned? Are these clamp diodes or similar? If diodes are used, which lines are they connected to?

  2. In the datasheet section [5.12.1.3 Power-Down Sequencing], it states that the potential difference between VDDS/VDDS_CLKOUT and VDDSHVx[x=1-11] must always be less than 2V during power-down. Is it correct to assume that VDDS/VDDS_CLKOUT exceeding VDDSHV[x] during the power-down sequence is not inherently problematic, as long as the 2V differential requirement is met? Please confirm this understanding.

 

Best regards,
Goto

  • +1
    TI__Mastermind 23351 points

    Hi,

    Thanks for reaching out. We do not share information about the internal device architecture. Customers must follow the slew rate requirements documented in the spec.

    Regarding the question about sequencing, the ideal implementation is to have VDDS and VDDS_CLKOUT ramping down after all the VDDSHV supplies are OFF. If this is not possible, then your understanding is correct. In addition to the "<2V" voltage difference, we also recommend maintaining the VDDS and VDDS_CLKOUT voltage ≥1.5V while the other supplies fully ramp down to minimize in-rush currents.

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    TI__Expert 5350 points

    Hi Brenda, 

    Thank you for answer.

    Brenda Diaz said:
    Regarding the question about sequencing, the ideal implementation is to have VDDS and VDDS_CLKOUT ramping down after all the VDDSHV supplies are OFF. If this is not possible, then your understanding is correct. In addition to the "<2V" voltage difference, we also recommend maintaining the VDDS and VDDS_CLKOUT voltage ≥1.5V while the other supplies fully ramp down to minimize in-rush currents.

    There is about 200ms interval between the ramp down of VDDSHV to the ramp down of VDDS/VDDS_CLKOUT.
    Is this interval no problem

    Best regards,
    Goto

  • 0 in reply to Shuhei Goto
    TI__Mastermind 23351 points

    Just to make sure I understand what your are describing in the previous message: is VDDSHV turned-OFF 200ms before VDDS/VDDS_CLKOUT?

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    TI__Expert 5350 points

    Yes, that's right.

    Best regards,
    Goto

  • +1 in reply to Shuhei Goto
    TI__Mastermind 23351 points

    Hi,

    Not sure if I'm understanding the concern here. Turning-OFF VDDS/VDDS_CLKOUT after VDDSHV  is actually that the datasheet recommends. 

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    TI__Expert 5350 points

    Hi

    The concern that "the interval between VDDSHV turnig-off and VDDS/VDDS_CLKOUT is 200ms. Is this not too long?"

    Thank you,
    Goto