• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 99 subscribers
  • Views 302 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

OMAP3530 SYS-nRESWARM signal beahvior during ESD

Habib Farahani
Prodigy 110 points
Other Parts Discussed in Thread: TPS65920

We are experiencing some ESD issues with the OMAP3530CBB and are considering not using the SYS_NRESWARM  (AF24) signal. This appears to be a bidir open drain signal. We have this signal running directly to the companion chip (TPS65920) pin B9, which is named RESWARM. In addition, it is pulled up through 100 ohms and the pullup is bypassed with 1000pF cap. We connected these two signals based on reference designs. We are not using a pushbutton switch on this line, as at least one reference design does.

 

Our system seems to show improved ESD immunity when this signal is tied high. We would like to know if there are reasons why we should not just tie this pin high at the OMAP? For example, will it affect synchronization between the OMAP and companion parts? It would be unfortunate if we pursued this approach, only to later find that it is a restriction.

  • 0
    TI__Intellectual 2820 points

    Hi Habib,

    We are looking into your question and will reply.  Please allow us some time. 

    Thanks,

    Lawrence

     

  • 0
    TI__Guru* 85820 points

    It would not be a good idea to tie this high.  This signal goes low when OMAP is reset and stays low for a little time after SYS_PWRONRST goes high.  The PMIC can also use this reset to trigger certain events, but it is not absolutely necessary to use this signal.

    Typically, you would pull this high to 1.8V with a 4.7K resistor.  No bypass capacitance is needed.   If you don't want use this function, you can disable it by changing the PAD_CONFIG for this pin to mode 7 (safe_mode). 

    Regards,

    james