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MSP430FR5870: Wake up time using 32K external crystal from power 0V

Part Number: MSP430FR5870

Hi Champs,

I would like to confirm 32K external crystal wake up time from initial power on for MSR430FR5xx.

because, in our use cas, crystal start up time from power input  need keep less than 300msec.

Could you input this information ?



  • The application report MSP430™ 32-kHz Crystal Oscillators (SLAA322) says:

    Start-up times between several hundred milliseconds and a few seconds are normal values for low-frequency tuning-fork crystals, like 32768-Hz crystals. The start-up time of a crystal oscillator depends on various factors:

    • The oscillator frequency influences the start-up time. A 32-kHz crystal oscillator starts relatively slowly, compared to a crystal oscillator with a high frequency, e.g., above 1 MHz.
    • High Q-factor crystal oscillators typically start slower than crystal oscillators with higher frequency tolerance.
    • Crystal with low load capacitance typically start faster than crystals requiring high load capacitance.
    • Crystals with low ESR start more quickly than high ESR crystals.
    • Oscillators with high OA (Oscillation Allowance) start faster than low OA crystal oscillators.

    The kick-start hack described in section 5.4 is not available on the FR58xx family because there is no shared LF/HF oscillator, and even that would not have guaranteed 300 ms.

    If "a few seconds" is too long for you, set the MSP oscillator to bypass mode and use an external oscillator that is designed for a faster start-up. (For example, Abracon's ASEK datasheet claims 28 ms.)

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