About EPWM BLOCK - TI C2000 DC/DC Buck Converter Example

Hello Everyone,

I have basic question about f28379d EPWM block in this example -> (https://www.mathworks.com/help/supportpkg/texasinstrumentsc2000/ug/dc-dc-buck-converter.html)

And I watched the related video about this example ---- > (https://www.youtube.com/watch?v=CstjgrGR7dY)

According to working principle of ADC , We don't make the ADC start of conversion,while pwm transitioning . For this reason ADC start of conversion launchs the conversion before the X(any time) of period.

In buck example with f28379d , and its EPWM block as following:

This is provided via CMPB value. Period is 1000. When counter is equai to CMPB value , ADC will start conversion as you can see at CMPB value.

But I didn't understand how to choose CMPB value as (15+54)/2 ? What are the mean 15 and 54 values ? Where do they come from ?

Can you explain briefly ?

Manythanks.

Burak .

Answer 1

[Venkatesh Chilapur]

Hi,

The first factor i.e 15 is related to the ADC SOCx acquisition window. The second factor i.e 54 is time from the end of the S+H window until the ADC results latch in the ADCRESULTx register. Refer the ADC block in the model and the controller TRM for more details. Since we have 2 SOC's configured here, hence the mutiplication factor of 2.

HTH,

Regards,

Venkatesh C

[Burak Caykenari]

Hi Venkatesh ,

Thank you for answers . I absolutely understand first factor of 15 , ADC SOCx acquistion window value. But I didn't understand second factor and multiplacation factor .

I have used F28379D Launchpad and its adc block.

In the second factor you mean from end of S+H window until Adc Register duration TLat time . Isn't it ?

According to your sentence : 'Refer the ADC block in the model and the controller TRM for more details' What is the controller TRM ? How can I found the second factor value for any other applications ?

Finally ın this example, there are two adc like following :

Hence there are 2 SOCs. If there existed 4 adc(4 SOC) for my application (assume) , multiplication factor is 4? Isn't it ?

Is there any formula for multiplication factor ? Is this only depends on the number of ADC (number of SOC) ?

I'm the new about these topics. Thank you for your help and informations.

Burak

[Burak Caykenari]

I'm looking for your response , If you are available. .

Thanks in advance .

[burak caykenari]

Can anyone explain this ?

[Venkatesh Chilapur]

Hi Burak,

In the second factor you mean from end of S+H window until Adc Register duration TLat time . Isn't it ? Yes

According to your sentence : 'Refer the ADC block in the model and the controller TRM for more details' What is the controller TRM ? How can I found the second factor value for any other applications ?

TRM – Technical reference manual.

The value can be picked up from the table you posted depending the ADC prescale ratio as set under hardware configuration pane and ADC tab.

In this case the prescale ratio is 5, hence a value of 54 (55 in table)

Hence there are 2 SOCs. If there existed 4 adc(4 SOC) for my application (assume) , multiplication factor is 4? Isn't it ?

Depends on the SOC are part of the same ADC module – like in this case both SOC belong to ADC-C.

Hence they cannot run in parallel, only in one after the other.

But lets say, you have one SOC in ADC-A module and other in ADC-C, since they are different ADC module, they can run parallel.

Regards,

Venkatesh C

[burak caykenari]

Hi Venkatesh ,

Thank you for clear answers.

My final question, I'm asking for confirmation :)

'But lets say, you have one SOC in ADC-A module and other in ADC-C, since they are different ADC module, they can run parallel.'

In this time equation is (1000-(15+54)). ?

These informations which you gave was very useful , I really appreciate you .

Manythanks.

[Venkatesh Chilapur]

Correct!