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  • Resolved

MSP430F5659: Glitch at DAC0 on pin P7.6 when togling digital output P6.6

Part Number: MSP430F5659

I have configured DAC0 to P7.6, output to 400 mV.

P6.6 (which could be configured as DAC0 too) is configured as digital output, not as DAC0.

When rising P6.6, I see DAC0 falling for about 15 us.

Any solution for this? Thank you.

  • The DAC is set to 80 mV, not 400 mV. It falls immediately to 0 V for 10 us. It then rises for 7~8 us back to the 80 mV.
  • Hi Gabriel,

    I will check your question and reply you soon.

    If my post helped solve your issue, please click on the  VERIFY ANSWER    button. 

    Wei,

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  • In reply to Wei.Jetim Zhao:

    Increasing the current of the DAC's input buffer does not help. Increasing the current of the output buffer helps reducing the glitch duration, but not its amplitude.

    Thank you.

  • In reply to Wei.Jetim Zhao:

    No news yet?

    Regards,

    Gabriel

  • In reply to Gabriel Barbat:

    Hi Gabriel,

    As a sanity check, please confirm that the DAC12OPS bit is set and DAC12AMPx is greater than 1 (I'm quite confident of this based on your reply from 12/6). Also try changing the output drive strength by setting the PxDS register bits accordingly. I will ask the Design Team if it is possible that the pad logic is causing this issue but responses will be delayed due to the holiday season.

    Regards,
    Ryan

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  • In reply to Ryan Brown1:

    Hi Ryan,

    DAC12OPS is set.

    DAC12AMPx is what I changed before.

    Now I tried setting PxDS on P6.6 only, on P7.6 only and on both. It didn't help in any case.

    I'm not sure what you mean with "pad logic".

    Thanks,

    Gabriel

  • In reply to Gabriel Barbat:

    Hi Gabriel,

    Regards, Ryan

    To better aid the community, please click on the "This Resolved my issue" button whenever a post answers your question!

  • In reply to Ryan Brown1:

    Got it. Please let me know if you have more information.

    Gabriel

  • In reply to Gabriel Barbat:

    I have replicated this behavior with and am discussing this behavior with the Quality Team, in the meantime have you considered using a capacitor to alleviate the issue?

    Regards,
    Ryan

    To better aid the community, please click on the "This Resolved my issue" button whenever a post answers your question!

  • In reply to Ryan Brown1:

    I actually already have a 100 pF capacitor. I didn't evalute the behavior either without the capacitor or with a bigger capacitor. Increasing the capacitor could increase the settling time. I need it to be less than ~50us.

    Could you suggest a capacitor value that would help?

    Thanks,

    Gabriel

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