TMS320F280049M: DPS: EPWM + CMPSS

Part Number: TMS320F280049M

We are trying to setup synchronous buck in peak current mode with TMS320F280049M.

We try to use Comparator subsystem 1 to generate events:

-> we synchronize TBPRD with comparator CMPSS (DCAEVNT1.sync loads TPHS=0 to TBPRD)

-> we turn off high EPWM1 at peak current (defined by DAC of High Comparator CMPSS) (DCBEVNT1 with T1 event connected to Action Qualifier – T1 force EPWM1A low, and should force EPWM1B high)

We get following results shown on pictures.

Fig.1: compare level set at the peak of triangular signal - it works OK: Deadtime and EPWM1B starts directly after the DACH is reached.

Fig.2: issue happens when we reduce DAC value, EPWM1B do not start after dead time DT2 elapse. Instead, EPWM1B is delayed (probably due to comparator level is long active)

How can we achieve the EPWM1B go active right after DT2 elapse?

Regards, Bernd