[Piccolo 2803x] Application Note: Digital Peak Current Mode Control with Slope Compensation

Very nice work ... I am sure users will benefit from this application note . Here are few comments/suggestions which I believe will make this information even more useful.

1. The application note doesn't provide bandwidth information needed to implement this system. There are no information on required memory space either. The code structure should be further clarified.

2. The application note doesn't describe the hardware setup which would have made it easy for one to duplicate the implementation. Very important for checking out concepts and validate claimed benefits and also to reduce support calls :-)

3. Didn't notice code download option - apparently the code is copy right protected ... is that the correct situation? If so, the benefit of this will be unfortunately reduced.

4. I really wished there would have been a benefit discussion on digital implementation of this system using a C2000 device. There are other analog/digital solutions available so the obvious question for a new user will be - why this? :-)

Anyway, this is a great work and keep up the initiative.  Thanks.

Arefeen,

Thank you for your comments - They have been noted and I have passed them along.

Have a good weekend :)

Lori

Arefeen,

Thanks very much for your feedback. The inputs are helpful and noted. Hopefully we'll have a chance to refine the material by adding the information you suggest soon.

Regarding point #3, a zip file containing all the files a user would need to run CMC as described was added to the download page today.

Best regards,

Richard 

the page with the SW download is here

http://focus.ti.com/general/docs/litabsmultiplefilelist.tsp?literatureNumber=sprabe7

Hi,

Is the application note removed? I am very interested in it but no where I can find it.

It has been removed. May revive later.

Lori, the link to this application note is broken on this post and on: http://www.ti.com/ww/en/analog/digital-power/index.html. 

Hi,

Is the application note available now?   Any updates on this situation?

Thanks,

Frank

The entire application software is available in controlSUITE using a PSFB topolgy,

controlSUITE\development_kits\HVPSFB

The applictaion note link is still broken,

Thanks a lot, Manish.

Frank

Hello Lori,

I have two questions regarding this:

1) This application note describes an implementation of peak current mode with the slope compensation calculated by the CLA, instead of the built-in slope compensation of the comparator module in the Piccolo devices. The built-in ramp seems to be a much better solution.

Why did they do it like that? is there a bug or a problem in the built-in slope compensation that makes it useless?

I'm about to implement peak current mode in a new product and I would need to know if there is something wrong with it.

2) My other question is: Is there any way of implementing peak current mode and use the dead-band capability? looks like the dead-band module is before the trip module in the block diagram so there is no way to apply dead-times to PWM signals toggled by the comparator. I am right? Why did they do it like this?

Thanks,

Max

Hello Max,

The application note (sprabe7a) was jointly written with Ali Shirsavar from our third party, Biricha Digital Power before characterisation of the internal ramp generator was complete.  At the time, ramp generation using the CLA was the best solution available, and does work well.  The internal ramp generator is now available in some devices and, as you say, offers a simpler solution to peak current mode control. 

Both methods rely on tripping the PWM immediately the comparator output changes.  There is currently no provision internally for dead-band on a trip event.

Best regards,

Richard

Hello Richard,

Thank you for the response.

I have another question: We are configuring the comparator module for peak current mode control, but it looks like the comparator action (turn off switch) does not get latched. This is bad because it produces the MOSFETs to turn on and off several times if there is noise present in the current measurement (which is usually the case in switch mode converters). Is there any way to have the comparator action latched in CBC mode?

Thanks,

Max

Hello Max,

You have to ensure that the trip condition is maintained for at least three TBCLK cycles, otherwise the trip event may not be latched in the TZ module.  See (for exmple) the note in section 3.2.9.3.1 of the F28069 User's Guide (spruh18c).

Best regards,

Richard