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TIC10024-Q1: Example For Ignored Switch Position Change Between 2 Wetting Current Cycles; other case than the datasheet waveforms

Yoshiki Ochi
Expert 8265 points
Part Number: TIC10024-Q1

Hi team,

Datasheet shows "Figure 8-13. Example For Ignored Switch Position Change Between 2 Wetting Current Cycles", could each lower case handle switch state change reflecting in SCC bit in INT_STAT and IN_STAT_COMP register?

1) nINT asserts low continuously, switch state change happens within tpoll_act_time (wetting current flowing)

2) nINT de-asserts and high state, switch state change happens outside tpoll_act_time (no wetting current flowing)

Regards,
Ochi

  • 0
    TI__Mastermind 26536 points

    Ochi-san,

    Please let me know if I am understanding your question correctly. I believe you are asking whether "1)" and "2)" represent the two possible cases of a switch state change related to the application of the wetting current.

    The device cannot recognize a state change until the wetting current is applied. Thus, if a state change occurs while wetting current is not applied (as is shown in Figure 8-13), then the device will not recognize the switch state change. Thus, SSC/INT_STAT will not be asserted. If the state change happens during the wetting current, or if the wetting current is applied while the switch is in the changed state, then the switch state change will be recognized and SSC/INT_STAT will be asserted.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    TI__Expert 8265 points

    Hi Danny, 

    Thank you. I understood. 

    One more additional question for continuous mode. MSDI will always sink/source Iwet if switch close, but it has just one comparator internally shown in its functional block diagram. So it could detect status change by each IN0 to IN23 in sequence fashion.

    Then, what is benefit of continuous mode compared with polling mode? Polling mode looks achieving the same detection period but low consumption current  compared with continuous mode; polling mode monitors if Iwet is flowing, which is in sequence fashion for each input and continuous mode always flow current but monitor just only in sequence fashion. 

    Regards,
    Ochi

  • +1 in reply to Yoshiki Ochi
    TI__Mastermind 26536 points

    Ochi-san,

    You are correct. There is a common misconception about this part that in continuous mode it is always monitoring all switches simultaneously. You are correct in understanding that it is sequentially monitoring the switches with the comparator, similar to polling mode.

    This use case can be beneficial for situations where wetting current needs to be more constant, rather than applied intermittently to a switch. For the most part, though, using polling mode is a better option as it allows reduced current consumption.

    Yoshiki Ochi said:
    polling mode monitors if Iwet is flowing, which is in sequence fashion for each input and continuous mode always flow current but monitor just only in sequence fashion.

    In short, yes, this is correct.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    TI__Expert 8265 points

    Hi Danny, 

    Thank you, I understood if external switch needs continuous current, only then continuous mode is needed. 

    Regards,
    Ochi