SPRUIZ1B July 2023 – August 2024 TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1
To make sure that the minimum dead band property is not violated, as the application switches between normal mode and DE mode and due to the PWMs potentially switching based on trip inputs, a minimum dead band circuitry show in Figure 22-62 is required.
The minimum dead band block provides the ability to configure the minimum dead band duration between a complimentary set of PWMs.
Minimum dead-band logic involves generating a blocking signal (BLOCKA, BLOCKB) after the falling edge of the EPWMA/B_DE. These block signals are used to block transition on the other signal. The input to BLOCKA(B) signal generators is configurable. Normally the sources are EPWMA/B_DB_NO_HR. However, there is a provision provided to select any of the MINDB X-BAR outputs. This provides flexibility to support some of the other application scenarios.
The selected source is fed to the BLOCK signal generation logic. Block signal generation involves, detecting the falling edge based on which BLOCK signal goes high and stretching the BLOCK signal for DELAYA/B cycles, which are software configurable.
In Figure 22-64 and Figure 22-65, EPWMxA_DE and BLOCKB are getting ANDed and EPWMxB_DE and BLOCKA are getting ANDed.
Figure 22-66 illustrates that a rising edge during the delay application does not affect the BLOCKA generation, same behavior is applied to BLOCKB.
Figure 22-67 showcases what happens when another falling edge occurs during the delay application. In this scenario, BLOCKA stays low until both DELAYA values are complete, same behavior is applied to BLOCKB.