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Original question:
Hi,
I'm working on TMS320F280049C for phase shift full bridge DC-DC converter application. I'm configuring EPWM1 and EPWM2 for the primary switch operation. The primary switches are controlled with 0.5 duty cycle and phase shift between EPWM1 and EPWM2. As explained in the datasheet, the phase shift between EPWM1 and EPWM2 can be done by putting value in the TBPHS register which will be loaded to the TBCTR when input synchronization pulse is detected. It is also stated in the datasheet that there is a delay from the internal master module (EPWM1) to slave module (EPWM2) which is:
In my case, I set the Prescaler = 1 and TBPRD = 200 so it will make 250 kHz PWM and delay based on the second equation (1x TBCLK) which is 10 ns. However, the actual delay I got was 20 ns as can be seen in the picture below
When I checked the PWM with other prescaler values (2 and 4) at the same frequency (250 kHz), the delay between EPWM1 and EPWM2 was correct.
I can compensate for this delay in the phase shift command. But I need to know if there is any reason for this. Or is there an exception only for Prescaler = 1? I want to keep using Prescaler = 1 as it will give me the highest PWM resolution.
Thanks,
Chaeyoung
