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MSP430F5310: MSP430F5310 LPM3 Question

shai eyni
Prodigy 90 points
Part Number: MSP430F5310

Hi all.

I use MSP430F5310.

The question is about LPM3 mode.

My circuit consumption is 2.5uA.

If   XT1LFOFFG in UCSCTL7 is “1” & OFIFG in SFRIFG1  is “1”, the current will rise to 5.6uA until those bits will be reset.

Please send me TI PDF section that confirm this issue.

Thanks.

 

  • 0
    Genius 3255 points

    Do you think it might be related to the following (page 170 of the User's Manual: www.ti.com/.../slau208p.pdf):

    "If a fault is detected for the oscillator sourcing MCLK, MCLK is automatically switched to the DCO for its clock source (DCOCLKDIV) for all clock sources except XT1 LF mode. If MCLK is sourced from XT1 in LF mode, an oscillator fault causes MCLK to be automatically switched to the REFO for its clock source (REFOCLK). This does not change the SELM bit settings. This condition must be handled by user software."


  • 0 in reply to Mike Tooma
    Prodigy 90 points
    Hi
    Thanks for your reply.
    I cant see the PDF file because the ling is not good.
    I saw another PDF and i didn't see any reference to LPM3 current increase.
    That what i'm searching for.
    I didn't reset those bits and the software was working fine except the LPM3 mode current consumption.
    The timing was ok.

    I will continue searching.

    Thanks again.

    Shai.
  • 0 in reply to shai eyni
    Genius 3255 points
    Shai,

    Switching the clock source from the LF XT1 to REFOCLK could create the extra current consumption. As stated above, the switch happens when the IFGs you mentioned are set.
    I have the link stated again here: www.ti.com/.../slau208p.pdf
  • 0 in reply to Mike Tooma
    Prodigy 90 points

    hi.

    so, if XT1LFOFFG in UCSCTL7 is “1” & OFIFG in SFRIFG1 is “1” the MSP works on REFOCLK until i will reset those flags ? or it
    works on LF XT1 and what that remained me to do is to reset those flags?
    Note that - The timing on my software was ok.

    It is very important for me to know: why the current consumption is 2.5uA more if the flags are in "1" .

    Where can i find the exact to paragraph that refer to this mode.

    Thanks for your help.

  • 0 in reply to shai eyni
    Genius 3255 points

    The extra current consumption could be related to the silicon needed to make REFOCLK.

    I think you would be better off getting this data empirically. Just make the REFOCLK the source of your clock and verify the current consumption.

  • 0 in reply to Mike Tooma
    Prodigy 90 points
    The "problem" is that i need it written in a pdf of the MSP.
    I know that it takes more current but i need some evidence in a documentation of the chip.

    Do you think that i can find it written ?
  • 0 in reply to shai eyni
    Genius 3255 points

    It looks like TI has what you need. See Caleb's input below.

  • 0 in reply to shai eyni
    TI__Genius 15370 points

    Hi Shai, 

    I agree with Mike Tooma on this one. The DCO is most likely switching to being sourced from XT1 to the internal REFO. The REFO would cause an increase the overall current consumption. You can find the typical REFO current consumption in the Internal Reference, Low-Frequency Oscillator (REFO) section of MSP430F5310 and MSP430F530x Mixed Signal Microcontrollers:

    Here you can see the typical consumption is 3uA which aligns well with the 2.5uA increase you are observing. 

    Best regards, 
    Caleb Overbay

  • 0 in reply to Mike Tooma
    Prodigy 90 points
    Hi.

    So, if there is a short or momentary problem with the external 32768 and the MSP start to work with his internal 32768, the LPM current will be ~2.5 uA more and the total will be ~5uA?
    As long as the fault bit OFIFG will stay in "1" and i will not reset it, the MSP continue works with the internal 32768?

    Thanks.
  • 0 in reply to shai eyni
    TI__Genius 15370 points

    Hi Shai,

    Yes, as Mike quoted in his first post:

    Mike Tooma said:

    "If a fault is detected for the oscillator sourcing MCLK, MCLK is automatically switched to the DCO for its clock source (DCOCLKDIV) for all clock sources except XT1 LF mode. If MCLK is sourced from XT1 in LF mode, an oscillator fault causes MCLK to be automatically switched to the REFO for its clock source (REFOCLK). This does not change the SELM bit settings. This condition must be handled by user software."

    The DCO on this part is stabilized using an FLL. This FLL requires a source clock and can be sourced from either the internal REFO or the external oscillator. If an external oscillator is not present, it will default to the REFO.

    Best regards, 
    Caleb Overbay

  • 0 in reply to Caleb Overbay
    Prodigy 90 points
    THANKS you all.
    I think that the current issue is clear now.

    Thanks again.

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