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MSP430FR2475: How to get a fast startup after PON

DJ-NG
Genius 9230 points
Part Number: MSP430FR2475

Hi MSP champs!

Customer need to have a fast system startup.

He found an system startup of 6ms in his system, even typ DCO FLL lock time is 200ms.

Q:     How is this to be interpreted (see table below)?

What can we do to have fastest startup time ?

  • 0
    Guru 88490 points

    The FLL takes some number of REF ticks to lock. However, if you don't wait for the FLL to lock, it will continue to settle in the background. In the meantime, your clock is "not too far off". I find that there are many things -- particularly startup things -- which can be done with a mediocre clock. 

  • 0
    TI__Expert 7015 points

    Bruce is right. If the startup time is defined as the power on to the first CPU command execution, it will be faster than FLL lock. 

    The DCO will oscillate to provide clock to MCLK for CPU execution. The clock may be not accurate until the FLL locked. 

    If you want to get faster system startup and also FLL lock faster, you can load the calibrated expected DCOTAP value into CSCTL0 and CSCTL1 register. Please refer to the user's guide slau445 CS (clock system) chapter for details. 

    Thanks,

    Lixin 

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