CBC Triggered
DPWMA
DPWMB
Positive Dead Time
DPWMA
DPWMB
Negative Dead Time
DPWM Control Register 0 (DPWMCTRL0)
55
SNIU028A – February 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
Digital Pulse Width Modulator (DPWM)
Figure 2-14.
Even if DPWMB is being used as a GPIO, it is important to program Event 3 for dead times with CBC.
Resonant/Multi Mode
In resonant/multi mode, the systems are often symmetrical. In this case, DPWMB may need to be
controlled by the Cycle by Cycle Fault logic as well. Sometimes a shortened on time on one DPWM pin
needs to be followed by an equal length on time on the other DPWM pin to prevent an offset from building
up in a capacitor or inductor. In this case, it is possible to enable duty cycle matching in these two modes.
If DPWMA or DPWMB is cut short by a CBC event, the next pulse, on the other DPWM pin, will also be
shortened to the same length.
Here are the states for resonant and multi modes:
•
All cleared - no CBC
•
Only CBC_PWM_AB_EN set - CBC on A and B, no duty cycle matching
•
CBC_PWM_AB_EN and CBC_ADV_CNT_EN set, CBC_BSIDE_ACTIVE_EN not set - CBC on A only
and B duty cycle matches to A
•
All three set - CBC on A and B, duty cycle matching both ways
Table 2-5. Truth Table
CBC_PWM_AB_EN
CBC_ADV_CNT_EN
CBC_BSIDE_ACTIVE_EN
CBC A
CBC B
Duty Match
0
x
x
0
0
0
1
0
0
1
1
0
1
1
0
1
M
B matches A
1
1
1
1
1
both match