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TDA4VH-Q1: RESET_REQZ has a drop problem when powered on

jingle.lan
Prodigy 120 points

Part Number: TDA4VH-Q1
Other Parts Discussed in Thread: TDA4VH, TDA4VM

Tool/software:

Hi all, 

   When testing the RESET_REQZ pin of the TDA4VH, we found that there was a drop problem, as shown below. At this point, we have disconnected the pin from the external connection. We want to know why this drop occurred. Will this fall have any effect?

  We encountered the same thing in our tests on TDA4VM. Look forward to an answer.

Thanks

  • 0
    TI__Guru 55877 points

    Hello,

    Is this during power-supply ramp up?  Is PORz and/or MCU_PORz asserted during this time frame?

    Can you capture scope shots of a few of the critical power rails ramping at the same time (IO supply, vdd_core, vdd_mcu)?  Is any one particular rail starting to ramp when the drop occurs?

    Thanks,
    Kyle

  • 0 in reply to kcastille
    Prodigy 120 points

    Hi,

     PORz and/or MCU_PORz  have not been pulled up yet,

    We  have captured the power on waveform of the power supply of the corresponding power domain of the pin, as shown by the green line.

    ps.This diagram comes from VM. We  designed an external pull-up connection to this power supply for this pin.

    .

  • +1 in reply to jingle.lan
    TI__Guru 55877 points

    Hello,

    This drop will not have any affect.  This is occurring during the initial power up with PORz and MCU_PORz asserted.  The RESET_REQz is an input signal and it's state is "don't care" until the system is powered and fully operational.

    Regards,
    Kyle