UCD3138: problem about void init_dpwm1(void) {} in UCD3138 firmware

zoujiangyilang

Part Number: UCD3138

Hello
I recently learned about UCD3138's full-bridge hard-switch firmware
I have some questions about void init_dpwm1(void) {}
Void init_dpwm0(void) // DPWM1B is Used to drive Sync-FET
{
Dpwm0Regs.DPWMEV3.all = (pmbus_dcdc_config[0].period >> 1);
}
I know this sentence is to set the start position of event3, which is DPWMB, in half the switching period.
I found in the UCD3138 Digital Power Supply Controller Technical Reference Manual,

DPWM B Rising Edge=Event1+filter Duty+Cycle Adjust A+(Event3-Event2),
Will the two have the same meaning? Why in the firmware
Dpwm0Regs.DPWMEV3.all = (pmbus_dcdc_config[0].period >> 1);

to set Event3 instead of setting according to the definition of the manual guide?
Thank you

over 6 years ago

0 zoujiangyilang over 6 years ago

Genius 4560 points

void init_dpwm0(void)
{Dpwm0Regs.DPWMCTRL0.bit.MSYNC_SLAVE_EN =0;}
void init_dpwm1(void)
{Dpwm1Regs.DPWMCTRL0.bit.MSYNC_SLAVE_EN =1;}
I know that these two sentences will be DPWm0 is master, DPWM1 is slave,
but I am not aware of the master and slave here, what does that mean?
Is the DPWM0 first wave? Or is the period of PWWM1 equal to the period of DPWM0?
Thank you

0 zoujiangyilang over 6 years ago in reply to zoujiangyilang

Genius 4560 points

void init_dpwm0(void)
{ Dpwm0Regs.DPWMCTRL1.bit.SYNC_FET_EN =0;}
void init_dpwm1(void)
{Dpwm1Regs.DPWMCTRL1.bit.SYNC_FET_EN =0;}
Why should the synchronous rectification function of DPWM0 and DPWM1 be disabled?
Does the development board drive secondary synchronous rectifiers from DPWM0B and DPWM1B?

0 zoujiangyilang over 6 years ago in reply to zoujiangyilang

Genius 4560 points

void init_dpwm1(void)
{Dpwm1Regs.DPWMCTRL1.bit.PRESET_EN = 1; }
DPWM1 enables Counter preset to Preset Count Value upon detection of sync ，
because it is a slave mode， Is its period more like DPWM0?

0 zoujiangyilang over 6 years ago in reply to zoujiangyilang

Genius 4560 points

The DPWM2 and DPWM3 modules are also initialized in the firmware, void init_dpwm2(void), void init_dpwm3(void).
These two modules are not used in the full-bridge hard-switch development board.
Why should the DPWM2 and DPWM3 modules be configured?

0 Yitzhak Bolurian over 6 years ago

TI__Mastermind 18370 points

When in closed loop (CLA_EN = 1), Dpwm0Regs.DPWMEV3.all = (pmbus_dcdc_config[0].period >> 1); does not mean that Event3 is in the middle of period. The absolute value of Event3 or Event2 do not matter just the difference between the two matters. The delta/difference between Event3 and Event2 determines the dead-time. The edge positioning itself is dictated by the filter(CLA).

0 Yitzhak Bolurian over 6 years ago in reply to zoujiangyilang

TI__Mastermind 18370 points

Means that they are linked together and synchronized, so they do not move or shift from each other.
Sync signal from master resets the counter from slave and slave starts to count.

0 Yitzhak Bolurian over 6 years ago in reply to zoujiangyilang

TI__Mastermind 18370 points

These bits only disabling the connection to ramp, not disabling the sync fet.
Also, many times the initialization is not the end of the story. We re-enable things later on when it is time. This can happen in one of the states of the state machine.

0 Yitzhak Bolurian over 6 years ago in reply to zoujiangyilang

TI__Mastermind 18370 points

PRESET works even if the DPWM is not a slave.
{Dpwm1Regs.DPWMCTRL1.bit.PRESET_EN = 1;} works together with {Dpwm1Regs.DPWMCNTPRE.all = pmbus_dcdc_config[0].period >> 1; // Shift by 180 degree ( half the period)} to get DPWM1 shift

0 Yitzhak Bolurian over 6 years ago in reply to zoujiangyilang

TI__Mastermind 18370 points

I remember that DPWM2 generates interrupts and also used for implementation of "Single frame".
Sometimes we use DPWMs internaly, even if the outputs are not used to toggle power FETs.

0 Yitzhak Bolurian over 6 years ago in reply to Yitzhak Bolurian

TI__Mastermind 18370 points

Please post your different questions in seperate posts. So if can serve others if they are looking for the same answer.

0 zoujiangyilang over 6 years ago in reply to Yitzhak Bolurian

Genius 4560 points

OK，Thank you.

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UCD3138: problem about void init_dpwm1(void) {} in UCD3138 firmware