SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The configuration options for the dead-band submodule are shown in Figure 14-34.
Although all combinations are supported, not all are typical usage modes. Table 14-8 documents some classical dead-band configurations. These modes assume that the DBCTL[IN_MODE] is configured such that EPWMxA In is the source for both falling-edge and rising-edge delay. Enhanced, or non-traditional modes can be achieved by changing the input signal source. The modes shown in Table 14-8 fall into the following categories:
Figure 14-35 shows waveforms for typical cases where 0% < duty < 100%.
Mode | Mode Description | DBCTL[POLSEL] | DBCTL[OUT_MODE] | ||
---|---|---|---|---|---|
S3 | S2 | S1 | S0 | ||
1 | EPWMxA and EPWMxB Passed Through (No Delay) | X | X | 0 | 0 |
2 | Active High Complementary (AHC) | 1 | 0 | 1 | 1 |
3 | Active Low Complementary (ALC) | 0 | 1 | 1 | 1 |
4 | Active High (AH) | 0 | 0 | 1 | 1 |
5 | Active Low (AL) | 1 | 1 | 1 | 1 |
6 | EPWMxA Out = EPWMxA In (No Delay) | 0 or 1 | 0 or 1 | 0 | 1 |
EPWMxB Out = EPWMxA In with Falling-Edge Delay | |||||
7 | EPWMxA Out = EPWMxA In with Rising-Edge Delay | 0 or 1 | 0 or 1 | 1 | 0 |
EPWMxB Out = EPWMxB In with No Delay |
Mode Description | DBCTL[DEDB-MODE] | DBCTL[OUTSWAP] | |
---|---|---|---|
S8 | S6 | S7 | |
EPWMxA and EPWMxB signals are as defined by OUT-MODE bits. | 0 | 0 | 0 |
EPWMxA = A-path as defined by OUT-MODE bits. | 0 | 0 | 1 |
EPWMxB = A-path as defined by OUT-MODE bits (rising-edge delay or delay-bypassed A-signal path) | |||
EPWMxA = B-path as defined by OUT-MODE bits (falling-edge delay or delay-bypassed B-signal path) | 0 | 1 | 0 |
EPWMxB = B-path as defined by OUT-MODE bits | |||
EPWMxA = B-path as defined by OUT-MODE bits (falling-edge delay or delay-bypassed B-signal path) | 0 | 1 | 1 |
EPWMxB = A-path as defined by OUT-MODE bits (rising-edge delay or delay-bypassed A-signal path) | |||
Rising-edge delay applied to EPWMxA / EPWMxB as selected by S4 switch (IN-MODE bits) on A signal path only. | 0 | X | X |
Falling-edge delay applied to EPWMxA / EPWMxB as selected by S5 switch (IN-MODE bits) on B signal path only. | |||
Rising-edge delay and falling-edge delay applied to source selected by S4 switch (IN-MODE bits) and output to B signal path only.(1) | 1 | X | X |
The dead-band submodule supports independent values for rising-edge (RED) and falling-edge (FED) delays. The amount of delay is programmed using the DBRED and DBFED registers. These are 10-bit registers and the value represents the number of TBCLK (time-base clock) pulses by which a signal edge is delayed. For example, the formula to calculate falling-edge-delay and rising-edge-delay is:
FED = DBFED × TTBCLK
RED = DBRED × TTBCLK
Where TTBCLK is the period of TBCLK, the prescaled version of EPWMCLK.
For convenience, delay values for various TBCLK options are shown in Table 14-10. The ePWM input clock frequency that these delay values been computed by is 100MHz.
Dead-Band Value | Dead-Band Delay (μs) | ||
---|---|---|---|
DBFED, DBRED | TBCLK = EPWMCLK/1 | TBCLK = EPWMCLK /2 | TBCLK = EPWMCLK/4 |
1 | 0.01 | 0.02 | 0.04 |
5 | 0.05 | 0.10 | 0.20 |
10 | 0.10 | 0.20 | 0.40 |
100 | 1.00 | 2.00 | 4.00 |
200 | 2.00 | 4.00 | 8.00 |
400 | 4.00 | 8.00 | 16.00 |
500 | 5.00 | 10.00 | 20.00 |
600 | 6.00 | 12.00 | 24.00 |
700 | 7.00 | 14.00 | 28.00 |
800 | 8.00 | 16.00 | 32.00 |
900 | 9.00 | 18.00 | 36.00 |
1000 | 10.00 | 20.00 | 40.00 |
When half-cycle clocking is enabled, the formula to calculate the falling-edge-delay and rising-edge-delay becomes:
FED = DBFED × TTBCLK/2
RED = DBRED × TTBCLK/2