UCC28180: clarifications about the M3 gain and on the signals transfers

Simone Mazzer

Part Number: UCC28180

Hello

I recall this old discussion for which no answer was given regarding the nonlinear gain parameter M3 introduced and calculated in the datasheet.
Its origin is particularly mysterious: I would like to point out two critical points:

The piecewise interpolant function reported in datasheet (latest review D) / application notes seems to be totally wrong.

See following pictures:

The plotted PW Function M3(V_COMP)

I would not agree at all with the transfer function reported in datasheet.

This point is the most important one. Unfortunately, to clarify my question, I'll have to go into a brief mathematical discussion of the PFC. Since is not an easy task to accomplish by writing in plain text, I've prepared a PDF document...I'd appreciate it if you could take a look at it.

2870.TI_ucc28180.pdf

Thank you in advance.

Simone

over 5 years ago

0 Simone Mazzer over 5 years ago

Prodigy 35 points

I would also like to point out that the M1M2(VCOMP) curve reported in the datasheet and the one graphed in the .xls design file file downloadable in the appropriate section of the site (http://www.ti.com/lit/zip/sluc506 , are in disagreement at leaest for high values of VCOMP.

I think that all these curve should be reviewed and clarified.

EDIT: Sorry, please don't consider this. I've looked in detail at the excel sheet, and the curve plotted in this last one was for a different frequency with respect to the one reported in the datasheet. My first question instead is valid, I kindly await your feedback.

Simone

0 Peter Meaney over 5 years ago in reply to Simone Mazzer

TI__Mastermind 31580 points

Hi Simone,

It will take a couple of days to review the curves, I hope to be able to give you an update then.

Regards

Peter

0 Peter Meaney over 5 years ago in reply to Peter Meaney

TI__Mastermind 31580 points

Hi Simone,

I have sent you a internal contact request so we can keep working on this. The original design team have moved to new roles since the release of this part and it will take more time to work through this.

I will close this post and we can stay in contact by email.

Regards

Peter

0 Simone Mazzer over 5 years ago in reply to Peter Meaney

Prodigy 35 points

Hi Peter,

I've just accepted your request.

Thank you.

Simone

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UCC28180: clarifications about the M3 gain and on the signals transfers

The piecewise interpolant function reported in datasheet (latest review D) / application notes seems to be totally wrong.

I would not agree at all with the transfer function reported in datasheet.