Hello,
I have found that in a switched power converter controlled by a C2000 DSC, the PWM immediate load mode cannot be used because it can cause the PWM module miss the duty cycle update. This happens, for example in a COUNT_UP mode, if CMPA is made lower than TBCTR before the output state is updated for that period. This issue has been posted in this forum in the past.
The problem with using shadow registers is that it causes a delay in the loop (which can be made no less than 1/2 the PWM period when using up/down count and updating at PRD and ZERO). I am working in a power converter and the phase margin of the loop is severely affected by this delay.
This issue could be easily fixed by hardware if they considered it to be an important issue, and maybe they are already considering it for future devices. At this point I am using a Piccolo 28069.
I am thinking in a workaround by software, but I would like to know if anybody has implemented something already. It´s not very easy to test if there are missed PWM cycles unless you close the loop with actual power and look for random perturbations.
Thanks,
Max
