UCD3138 datasheet(53/99 Pages) TI2

53 / 99 page

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.

9.6.4 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 9.5.2.2. Here is a diagram of this mode:

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

Figure 9-20. Resonant Symmetrical Closed Loop

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.

www.ti.com

UCD3138

SLUSAP2J – MARCH 2012 – REVISED NOVEMBER 2021

Submit Document Feedback

Product Folder Links: UCD3138

UCD3138 датащи(PDF) 53 Page - Texas Instruments

UCD3138 датащи(HTML) 53 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

датащи скачать

ссылки URL