• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 99 subscribers
  • Views 216 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.

C5535: VSSRTC pin handling

Kaka
Guru 24520 points

Hi community member,

Please let me confirm the following question.

<Question>

Regarding to the processor wiki of C5535, "VSSRTC must not be connected to the board ground.

Would you please the reason why VSSRTC must not be connected to the board ground?

If this pin will be connected to the board ground, what kinds of issue will be happened?

Best regards,

Kaka

  • 0
    Mastermind 7925 points

    Hi Kato,

    Your question is very strange. Vssrtc allows device to continue ticking RTC without main power. With main power RTC peripheral is powered without Vssrtc.

    I suspect that if you ground Vssrts and power device you will case short-circuit somewhere on silicon. In best case you will damage RTC power circuit or RTC peripheral. In worst you will render whole device unusable.

    Edit: Vss is not Vcc.

    Regards,
    Maciej

  • 0 in reply to MaciejKucia
    TI__Mastermind 23785 points

    Vssrtc is the ground to use with external crystal. It is described figure 5-4, 5-5 & 5-6 on data manual. You can ground it with board ground if you are not using an external crystal as in figure 5-6. I don't know what happen if you ground it to board ground with an external crystal. Have you tried it?

    Regards. 

  • 0 in reply to Steve Tsang
    Guru 24520 points

    Hi Steve,

    Thank you for response/

    According  to customer experiment, if they connected the VSSRTC to the board ground with using external crystal, the application which used C5535 showed an improved tolerance for the static electricity.   So, if there any problem for this, they will connect the VSSRTC to board ground.

    I do not know why VSSRTC must not connect the board ground with an external oscillator.  I think that there are some reasons  that you described this to datasheet.

    Best regards,

    Kaka

  • 0 in reply to Kaka
    TI__Mastermind 23785 points

    Kaka-san,

    When you say "static electricity", do you refer to electro-static discharge, ESD?

    Regards.

  • 0 in reply to Steve Tsang
    Guru 24520 points

    Hi Steve,

    Thank you for your response.

    No, I did not refer to the specification of ESD.

    Customer said that if connected the VSSRTC pin to GND, the customer's application showed an improved tolerance for the static electricity.

    So, I think that ESD specification is not related to this question...

    Best regards,

    Kaka