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msp-fet430U38 question

Gaston_Melo_Arg
Mastermind 7675 points

what is the use of the  cristal of 32 khz  that came with the kit?

thanks

 

Gaston

 

  • 0
    Intellectual 980 points

    http://www.farnell.com/datasheets/319077.pdf

    check the above document might be it will be useful for u for clarifying your doubt

    Regards

    rahonaM B

  • 0
    Guru 17650 points

    Hi Gaston,

    For optimal low-power performance, ACLK can be sourced from a low-power 32,768-Hz watch crystal, providing a stable time base for the
    system and low power stand-by operation.

    Because of that, TI included a 32768-Hz watch crystal to the tool.

    The LFXT1 oscillator supports ultralow-current consumption using a 32,768-Hz watch crystal in LF mode (XTS = 0). A watch crystal connects to XIN and XOUT without any other external components. The software-selectable XCAPx bits configure the internally provided load capacitance for the LFXT1 crystal in LF mode. This capacitance can be selected as 1pF, 6pF, 10pF or 12.5pF typical. Additional external capacitors can be added if necessary. Refer to the Users Manual Chapter 5 for more details (http://focus.ti.com/lit/ug/slau144e/slau144e.pdf).


    The App-Note mentioned above is also an excellent source of information!
    Rgds
    aBUGSworstnightmare

  • 0
    Prodigy 10 points

    Gaston,

     

    The company I work for, Micro Crystal, supplies TI with the crystal that came in your kit. I previous response to your questions suggesting the Farnell website does provide an accurate detail use of the crystal. In simpler terms most MCU's internal RTC (real time clock) are not accurate enough to keep the time required in most applications, hence they need a frequency device to help keep time. many crystals can do this but a 32.768KHZ crystal is usually used because 1) two clock pulses = 1 second and 2) tuning forks(32.768KHZ) use less than 1uW of power, or in other terms<1/10 the power a MHZ value crystal would use

    The crystal that came with your kit has the optimal load cap that will work with the MSP430 you are using. We (Micro Crystal) have already done oscillator circuit verifications of all MSP430 product and frequency mapping across the operating temperature range. Note: Micro Crystal has worked with TI MSP430 engineering since the inception of the MSP430 product line

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