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SYS_32K Clock

Ken Turocy
Prodigy 160 points

What are the advantages or disadvantages to generating the 32KHz clock internally (sys_boot7 tied to VDDSHV) as opposed to using an external 32KHz oscillator (sys_boot7 tied to RET)?

Do I lose functionality by generating this clock internally?

  • 0
    TI__Intellectual 2695 points

    If u are using internal 32k clk generation, this would help u reduce ur system cost as u can eliminate additional 32k cystal frm board. As 32k required for device operation would be generated internally frm 26 MHz clk.

    Disadvantage of using this option would be that you can't turn HF clk when in off mode (deep sleep mode) lowest power state at system level. you would still be able to put device in OFF mode but to further reduce power you won't be able to turn OFF HF crystal (26 MHz) on board.

    Hence based on product need you would have option to choose based on system requirements.



    Thanks and Best Regards,
    Vaibhav Desai 

  • 0
    TI__Genius 16690 points

    Hi Ken,

    An internally generated clock only supports 32.5 kHz not 32.768 kHz so it can't be used for real time clock.

    advantages

    - reduce the BOM cost of a 32KHz oscillator

    disadvantages

    - can't be used for real time clock

    Regards,

    Kazunobu Shin