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Original question:

HRPWM in UP count mode not working as documented (period and dead-band)

TMS320F280049C: HRPWM Up-count, deadband module unavailable

Nishka Rao
Intellectual 1466 points
Part Number: TMS320F280049C
Other Parts Discussed in Thread: TIDM-DC-DC-BUCK

Tool/software:

Hi Team, 

I saw in the TRM, the following note: 

'

However, in our example design TIDM-DC-DC-BUCK, we set up the EPWM to be UP count mode, with the option to allow for HRPWM and a deadband of 150 ns.

What does the note in the TRM refer to?

  • 0
    TI__Mastermind 27616 points

    Hi Nishka,

    This note is a very generic note. Let me provide some more insight.

    If you're using up count mode, using dead band with high resolution is still possible. I have a test case in which show cases this.

    If you have a test case in which you're using up count mode and the HR is not working please provide it.

    However, under specific configurations of HRPWM in which this dead band may not work is when you're using up count mode and have two actions occurring in the same period which you need to control both edges. Then you'll need to use up down count mode with HR and deadband.

    https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/171/6038.hrpwm_5F00_ex2_5F00_slider.7z

    Best regards,

    Ryan Ma

  • 0 in reply to Ryan Ma
    TI__Intellectual 1466 points

    Thanks Ryan!

    I don't have a specific error, I have an application where we need to finely control the deadtime and we are using the Buck reference design as the base code. 

    Just to clarify, by 2 "actions" you mean 2 capture compare events triggering an output?

    The Buck code uses the ZERO to set one edge of the PWM and the CMPA to set the other edge, through the action qualifier. It is possible to tune both the rising and falling edge dead bands in this configuration correct?

    Thanks!

  • 0 in reply to Nishka Rao
    TI__Mastermind 27616 points

    Hi Nishka,

    You won't be able to tune the rising edge since it's set on ZERO event, but will be able to tune the CMPA edge with deadband hr.

    Best,

    Ryan Ma

  • 0 in reply to Ryan Ma
    TI__Intellectual 1466 points

     Hi Ryan,

    I'm confused because the buck code which we (TI) implemented does set both the rising & falling edge dead band, and uses UP count mode as shown below? 

    What would the erroneous output be when there are 2 actions with dead-band?

    Maybe i'm misunderstanding the HRPWM portion, because the MEP is only used on the CMPA edge not on the Zero edge.

  • +1 in reply to Nishka Rao
    TI__Mastermind 27616 points
    Nishka Rao said:

    Maybe i'm misunderstanding the HRPWM portion, because the MEP is only used on the CMPA edge not on the Zero edge.

    That is expected, that is fine. 

    Nishka Rao said:

    I'm confused because the buck code which we (TI) implemented does set both the rising & falling edge dead band, and uses UP count mode as shown below? 

    Sorry let me clarify, using the regular dead band on the ZRO event will work. The HR will not be applied on this edge.

    Best regards,

    Ryan Ma