Datasheet

Start of Period
Period Counter
Start of Period
Filter Period
Adaptive Sample Trigger A
Sample Trigger 1
DPWM Output A
Filter Duty – Average Dead Time
Event 1
Event 3 - Event 2
Period Register – Event 4
DPWM Output B
Blanking A Begin
Blanking A End
Blanking B Begin
Blanking B End
Phase Trigger
Sample Trigger 2
To Other
Modules
To Other
Modules
Resonant Symmetrical Closed Loop
Events which change with DPWM mode:
Dead Time 1 = Event 3 – Event 2
Dead Time 2 = Event 1 + Period Register – Event 4)
Average Dead Time = (Dead Time 1 + Dead Time 2)/2
DPWM A Rising Edge = Event 1
DPWM A Falling Edge = Event 1 + Filter Duty – Average Dead Time
Adaptive Sample Trigger A = Event 1 + Filter Duty + Adaptive Sample Register
Adaptive Sample Trigger B = Event 1 + Filter Duty/2 + Adaptive Sample Register
DPWM B Rising Edge = Event 1 + Filter Duty – Average Dead Time + (Event 3 – Event 2)
DPWM B Falling Edge = Filter Period – (Period Register – Event 4)
Phase Trigger = Phase Trigger Register value or Filter Duty
Events always set by their registers, regardless of mode:
Sample Trigger 1, Sample Trigger 2, Blanking A Begin, Blanking A End, Blanking B Begin,
Blanking B End
Filter controlled edge
Adaptive Sample Trigger B
UCD3138
www.ti.com SLUSAP2F –MARCH 2012–REVISED NOVEMBER 2013
The Filter has two outputs, Filter Duty and Filter Period. In this case, the Filter is configured so that the
Filter Period is twice the Filter Duty. So if there were no dead times, each DPWM pin would be on for half
of the period. For dead time handling, the average of the two dead times is subtracted from the Filter Duty
for both DPWM pins. Therefore, both pins will have the same on-time, and the dead times will be fixed
regardless of the period. The only edge which is fixed relative to the start of the period is the rising edge of
DPWM A. This is the only edge for which the blanking signals can be used easily.
Copyright © 2012–2013, Texas Instruments Incorporated Functional Overview 37
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