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TMS320F280025C: Question about dead band resolution

Julia Li
Expert 3540 points
Part Number: TMS320F280025C

Hi Champs,

Here are some question about dead band resolution 

1.

In TRM, it says "Just like the duty cycle restrictions when using HRPWM, the DBRED and DBFED values must be greater than 3 to use hi-res deadband."

And TRM also says "When using DBREDHR or DBFEDHR, DBRED and/or DBFED (the register corresponding to the edge with hi-resolution displacement) must be greater than or equal to 7."

So if we want to use a high-resolution dead band, how much should the values ​​of DBRED and/or DBFED be greater than? 3 or 7?

2. Can the high-resolution dead band module of F280025 be used to realize dead-zone control with a range of 0-100ns and a precision of 1ns? Customer now need to realize it. If the answer of the previous question is 7, according to my understanding, the value of the dead zone that can be realized in the range of 0-70ns is only 10ns, 20ns, 30ns... because only DBRED and DBFED can be used. Do we have other method to realize 1ns precision in the range of 0-70ns? Thanks!

Best Regards,

Julia

  • +1
    TI__Expert 7911 points

    Hi Julia,

    For the first question, please see this post for clarification on when each is relevant.

    For your second question, I would need additional detail to answer definitively. If HR Period control is enabled, then unfortunately, HR control at very low values is not recommended and can result in undefined values. See the following caution note from the device TRM section 17.15.1.5.3:

    If HR Period is not enabled, the only way that I can think of offhand would be direct control of the CMPxHR values, which is not always possible depending on configuration. (For elaboration on when this is and isn't possible, please see the TRM for HRPWM, section 17.15, and locate the details on the specific chosen configuration.)

    Regards,

    Jason Osborn