• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 62 subscribers
  • Views 2795 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.

TPS65631W Swire vs CNTL Differences

Hayden_Hast
Intellectual 1515 points
Other Parts Discussed in Thread: TPS65631W

Hello,

I'm working with a wearable application and am interested in using the TPS65631W. However, I see that a CTRL signal is used to program the output voltage of the inverting buck-boost converter (Vneg) instead of the common Swire protocol.

Upon inspection of the datasheet (section 8.5), I have found a few differences between SWIRE and the CTRL signal. I was hoping you could talk more in depth about these differences and how difficult it would be to switch to using the CTRL signal instead of SWIRE that is seen on most AMOLED power devices.  

Regards,

Hayden

  • 0
    TI__Guru 60265 points

    Hello Hayden,

    Would you please define more in detail which differences you observe between the CTRL signal and the common Swire protocol?

    If you have a reference for the common Swire protocol, this would be helpful.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Intellectual 1515 points

    HI Brigitte,

    Here are a couple links to devices that use Swire...

    Doing some initial investigations I found the following minor differences, but perhaps Swire isn't as common as I believed if you haven't been asked about it before. 

     

    • The Low-level threshold voltage of CTRL is 0.4V while SWIRE is 0.6V.

    • On time differences

      • Swire = 3uS – 75uS

      • CTRL = 2us – 25uS

    • The protocols are extremely similar but not the same. Look at the example of Swire with 3 high pules vs. CTRL with 3 high pules located in the datasheet for the TPS65631W and the STODA3AS.

    • The negative voltage levels that can be programed and what # of rising edges they correlate to differ from device to device. See the example tables from the TPS65631W and the STODOA3AS datasheets.

    Regards,

    Hayden

  • 0 in reply to Hayden_Hast
    TI__Guru 60265 points

    Hello Hayden,

    As far as I know there is not a standard for Swire as for example for I2C.

    Swire at the end is just counting pulses and the pulse count per programmed functionality is not specified in a generic specification.

    But back to your first question about the difficulty switching from Swire to CTRL:

    I expect that you are using a GPIO to drive Swire (I never heard about a controller with integrated Swire block, therefore my expectation). I do not expect that the low level on this GPIO is above 0.4V, therefore there should not be a problem with this difference.

    For the different voltages, I expect that you would need to either change the programming of your controller or if you have something like a truth table for these values you would need to update this truth table.

    According the timing of the high level, if the high level you are already using is between 3us and 25us you do not need to change anything, if it is higher than 25us, you would need to reduce it to 25us or below.

    For me it would be interesting if these changes generate a high workload on your side.

    I am sorry, but I was not able to locate any information about the product you mention, therefore I could not compare the tables.

    Best regards,

    Brigitte

  • 0 in reply to Brigitte
    TI__Intellectual 1515 points
    Brigitte,

    Thanks for digging into this for me.

    After also comparing the Swire examples to the CTRL signal, I agree with you in that it shouldn't take much work to adjust.

    Thanks again,
    Hayden