• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 789 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TMS320F28075-Q1: About the Dead-Band Generator (DB) Submodule

zhongwei guo
Prodigy 10 points

Part Number: TMS320F28075-Q1

Tool/software:

Hi,

I am currently using the TMS320x2807x for controlling the switching power supply.

I am interested in changing the dead time while the system is operating.

I would like to know if loading a new value into DBRED/DBFED while the DB counters are counting (specifically during the dead-time period) would affect the current edge. Please note that I am not using shadow mode.

Furthermore, could you please let me know whether the DB counter operates in decremental mode?

Best regards,

  • 0
    TI__Mastermind 27520 points

    Hello,

    The timing of updating any EPWM values/configurations (loading to the active register) will depend on your loading scheme or specific loading setting for that register. In general, if you use immediate load mode, the settings would load immediately when you run line the code to do so. This is sometimes NOT desirable since you are not truly controlling when the update is made (the update is made whenever the CPU gets to the code). Instead, many use cases will implement shadow loading schemes that are event-dependent. For example, you can set up EPWM action qualifier registers so that they load from the shadow (buffer-like) register to the active register ONLY when the EPWM counter reaches a certain value (such as the TBPRD value). In this way, you know exactly when the updated value/setting is being implemented and control it. I would suggest using shadow mode if you want to know when you are updating the values, otherwise, it is dependent solely on your program timing.

    Regular (non-HR Dead Band) can be used in any count mode. 

    Best Regards,

    Allison

  • 0 in reply to Allison Nguyen
    Prodigy 10 points

    Hi, Allison,

    Thank you for your reply.

    I have looked into a similar topic regarding the Delfino F28335.

    https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/74346/deflino-f28335-epwm-module-dead-band-generator-submodule

     Without utilizing shadow mode, I believe that the Dead-Band Generator Submodule of TMS320x2807x operates in the same manner as the F28335. If my understanding is correct, there should be no problems with my application. Could you please confirm if my understanding is correct?

    Thanks and Best Regards,

  • +1 in reply to zhongwei guo
    TI__Mastermind 27520 points

    Hello,

    The F2807x actually uses a different generation (or "type") of EPWM as noted in our C2000 Peripherals Guide: 

    So the EPWM module can have different capabilities depending on the EPWM type on that device (but these are on the order of feature enhancements or bug fixes from previous EPWM-types, not fundamental function changes, so the deadband function should be similar as you say). Still, is there a particular reason you do not want to use shadow loading?

    Best Regards,

    Allison

  • 0 in reply to Allison Nguyen
    Prodigy 10 points

    Hi, Allison:

    Thank you for your confirmation and the information. Because I have used immediate loading for the update of the dead band of another product, I want to know whether there is a risk of misoperation.

    From the Reference Guide and your explanation, it doesn’t show any modification about the immediate loading, so I believe that there is no risk of misoperation.

    Thanks and Best Regards,