• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 78 subscribers
  • Views 312 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MSP430FR6877: DCO frequency accuracy at every return from LPM to Active Mode (AM)

Cruijff
Expert 2760 points
Part Number: MSP430FR6877

Hi community member,

I have a question about DCO of MSP430FR6877(MSP430FR6xxx).

Is there possibility the oscillation frequency of DCO slight fluctuations every time DCO resumes oscillation at the transition from LPM3 to AM?
(DVCC = 3V, temperature is constant)

Best regards.
Cruijff

  • 0
    TI__Expert 6635 points

    Hi Cruijff,

    I found the following note in our datasheet:

    So yes, there is a possibility the frequency will fluctuate when waking up from LPM3, but it should settle back into the specified range.

    Thanks,

    Mitch 

  • 0 in reply to Mitch Ridgeway
    Expert 2760 points

    Hi Mitch 

    Thank you for your reply!

    >  I found the following note in our datasheet.

    The note of (1) is described in 16, 21, 24 MHz.
    Does it mean that other conditions (1MHz, 8MHz, etc.) are not included to this?

    And please you tell me your opinion about below:

    For example, suppose the DCO oscillation frequency before LPM3 was 1.010MHz.
    After MSP430 disables DCO with LPM3, wake up to re-enable DCO.
    Is the DCO frequency after LPM likely to fluctuate from 1.010MHz even if Vcc and temperature is constant?
    I guess it will not change greatly depending on temperature and voltage conditions.

    In extreme terms, is there possibility the DCO frequency before LPM be 9.965MHz and the DCO frequency after returning from LPM be 1.035MHz? 

    Best regards.
    Cruijff

  • 0 in reply to Cruijff
    Expert 2760 points

    Hi,

    Please tell me your view against my question.

    Best regards.
    Cruijff

  • 0 in reply to Cruijff
    TI__Expert 6635 points

    Hi Cruijff, 

    Sorry for the delayed response. 

    Good catch! Yes, it looks like that note does not apply for frequencies 1MHz - 8MHz. 

    Regarding "In extreme terms, is there possibility the DCO frequency before LPM be 9.965MHz and the DCO frequency after returning from LPM be 1.035MHz?"

    while this is technically possible (these values stay within the values given in the datasheet), this is highly unlikely if temperature and voltage remain constant. You might see a very slight change in frequency every time the DCO restarts, but I would expect it to be very minimal.

    Thanks,

    Mitch

**Attention** This is a public forum