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MSP430FR2633: ILPM3, CapTIvate, 1 MUTUAL button, wake on touch [uA]

Hideaki Nambu
Mastermind 9125 points
Other Parts Discussed in Thread: TIDM-CAPTIVATE-64-BUTTON

Hello.

ILPM3, CapTIvate, 1 SELF button, wake on touch  - - - This is 3.4uA as the DS.

Then my customer's question is the case of MUTUAL. My test result was 104uA. The value looks the same as the 64 button.

Q1. Do you agree with my test result ?  Approx 100uA for single MUTUAL touch.  Or the current should be smaller ?

Q2. I think that the recommended CapTIvate sensing method for sleep would be SELF or PROXIMITY. Is it correct ?

  • 0
    Mastermind 9125 points

    Sirs,

    For Q2 I found "Wake on proximity mode" would be good. A MUTUAL electrode works as PROXIMITY to exit from sleep and automatically back to the MUTUAL.

    When my MUTUAL electrode was working as the "Wake on proximity mode" sensor, the supply current was decreased from 104uA to 7uA. Very good.

    Please point out if any misunderstanding.

  • 0 in reply to Hideaki Nambu
    TI__Guru**** 202096 points
    Hello Hideaki,

    Active mutual mode must scan each Tx and Rx electrode initialized/used (16 total) which gates your power consumption above 100 uA, as you mentioned in the next post utilizing wake-on-proximity mode drastically reduces the current consumption to < 10 uA. As shown in the Using the Wake-on-Proximity State Machine Effectively section of the CapTIvate User's Guide, this is because the state machine allows for CPU-less measurement and processing for 1 element per measurement block (4 total) for which it is able to utilize LPM4 mode: software-dl.ti.com/.../ch_design.html

    Mutual mode is best realized in applications requiring >16 push buttons, where the shared Rx/Tx electrodes can help realize a true button matrix as demonstrated by TIDM-CAPTIVATE-64-BUTTON. Due to this, coupled with the fact that self capacitance mode is more sensitive to touch events, self capacitance is recommended for a single button. Wake-on-Proximity mode is recommended to sleep in LPM4 before a possible touch event is detected.

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Mastermind 9125 points
    Ryan,
    I appreciate your response. As you linked the UsersGuide has answered.

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