3.2.5.3 Operational Highlights for the Dead-Band Submodule
The following sections provide the operational highlights. The dead-band submodule has two groups of
independent selection options as shown in
•
Input Source Selection:
The input signals to the dead-band module are the EPWMxA and EPWMxB output
signals from the action-qualifier. In this section they will be referred to as EPWMxA In and EPWMxB In.
Using the DBCTL[IN_MODE) control bits, the signal source for each delay, falling-edge or rising-edge, can be
selected:
– EPWMxA In is the source for both falling-edge and rising-edge delay. This is the default mode.
– EPWMxA In is the source for falling-edge delay, EPWMxB In is the source for rising-edge delay.
– EPWMxA In is the source for rising edge delay, EPWMxB In is the source for falling-edge delay.
– EPWMxB In is the source for both falling-edge and rising-edge delay.
•
Half Cycle Clocking:
The dead-band submodule can be clocked using half cycle clocking to double the
resolution (that is, counter clocked at 2× TBCLK).
•
Output Mode Control:
The output mode is configured by way of the DBCTL[OUT_MODE] bits. These bits
determine if the falling-edge delay, rising-edge delay, neither, or both are applied to the input signals.
•
Polarity Control:
The polarity control (DBCTL[POLSEL]) allows you to specify whether the rising-edge
delayed signal and/or the falling-edge delayed signal is to be inverted before being sent out of the dead-band
submodule.
0
1
S2
1
0 S1
RED
Out
In
Rising edge
delay
(10-bit
counter)
(10-bit
counter)
delay
Falling edge
In
Out
FED
1
0 S3
0
S0
1
EPWMxA
EPWMxB
DBCTL[POLSEL]
DBCTL[OUT_MODE]
S5
DBCTL[IN_MODE]
1
0
S4
0
1
EPWMxA in
EPWMxB in
DBCTL[HALFCYCLE]
Figure 3-29. Configuration Options for the Dead-Band Submodule
Although all combinations are supported, not all are typical usage modes.
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
fall into the following categories:
•
Mode 1: Bypass both falling-edge delay (FED) and rising-edge delay (RED).
Allows you to fully disable
the dead-band submodule from the PWM signal path.
•
Mode 2-5: Classical Dead-Band Polarity Settings.
These represent typical polarity configurations that
should address all the active high/low modes required by available industry power switch gate drivers. The
waveforms for these typical cases are shown in
. Note that to generate equivalent waveforms to
, configure the action-qualifier submodule to generate the signal as shown for EPWMxA.
Enhanced Pulse Width Modulator (ePWM) Module
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
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Summary of Contents for TMS320 2806 Series
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