UCD3138 datasheet(52/89 Pages) TI1

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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

SLUSAP2G – MARCH 2012 – REVISED SEPTEMBER 2016

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Detailed Description

DPWMB can cross over the period boundary safely, and still have the proper pulse width, so full 100%

pulse width operation is possible. DPWMA cannot cross over the period boundary.

Since the rising edge on DPWM B is also fixed, Blanking B-Begin and Blanking B-End can be used for

blanking this rising edge.

And, of course, Cycle Adjust B is usable on DPWM B.

6.6.4

DPWM Resonant Mode

This mode provides a symmetrical waveform where DPWMA and DPWMB have the same pulse width. As

the switching frequency changes, the dead times between the pulses remain the same.

The equations for this mode are designed for a smooth transition from PWM mode to resonant mode, as

described in Section 6.5.2.2. Here is a diagram of this mode:

Figure 6-20. Resonant Symmetrical Closed Loop

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