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LAUNCHXL-F28379D: Error in F2837xD TRM?

Part Number: LAUNCHXL-F28379D

Is there an error in the technical reference manual? In the time base synchronisation page, attached, there is an example of a synchronisation scheme for a typical power converter.

However looking at the above, this doesn’t seem possible. I got this from a previous forum post after perusing the TRM. 

We had originally set up to use EPWM2 and EPWM6 for a phase shifted full bridge. Can someone please confirm that this would not work, as EPWM2 and EPWM6 are not connected and cannot be synchronised (in a simple manner). 

I have opted to instead select EPWM7 and EPWM8. Can someone further confirm that this would then work, as they are connected? 

EPWM7 does not use an external synchronisation pulse, and acts as a master And generates a master synchronisation pulse. It generates an output pulse on CTR=ZRO

EPWM8 synchronises to EPWM7 through this pulse. 

This seems OK via the TRM diagram, but do need to confirm due to the issue with the TRM, and we cannot directly test with the Launchpad as these pins are not set up as PWM pins. I think when I originally used EPWM1 and EPWM2, I did not have any external synch pulse for EPWM1, and it just sent one to EPWM2 and everything worked fine. I am using the most recent version of the TRM so it hasn’t been fixed in the new version. 

Best regards, 

JH

  • Hi JH,

    EPWM2 and EPWM6 are not connected and cannot be synchronised (in a simple manner)

    You are correct that EPWM2 and EPWM6 are not directly connected, so it would not be quite as simple to try to synchronize them. 

    I have opted to instead select EPWM7 and EPWM8. Can someone further confirm that this would then work, as they are connected? 

    This is correct - EPWM7 and EPWM8 and directly connected i.e. EPWM8 uses EPWM7's SYNCOUT as its sync source. 

    due to the issue with the TRM,

    I unfortunately am not too sure of which specific issue you are referring to in the F2837xd TRM. Could you please describe the error in documentation that is in question? (If this is from an old E2E, would you be able to provide the link to it so I can reference it?). 

    Best Regards,

    Allison