WEBENCH® Tools/TPS54360B-Q1: Compensation with low ESR aluminium capacitor

Michel de Jongh

Prodigy 55 points

Part Number: TPS54360B-Q1
Other Parts Discussed in Thread: TPS54360B

Tool/software: WEBENCH® Design Tools

We have a question with regard to the compensation of the TPS54360B in WEBENCH.

When using it with a low ESR capacitor it fails to compensate due to the fact that the cross-over frequency is too low.

The current design is as in this link

These compensation values are set using the formulas in the datasheet.

Can you tell us how we can compensate this design?

Kind regards,
Michel de Jongh

over 6 years ago

0 Timothy Hegarty over 6 years ago

TI__Guru 72702 points

Hi Michel,

For current-mode control, the compensator zero can generally be located at the load pole.

See here for more detail: www.how2power.com/.../H2PToday1406_design_TexasInstruments.pdf

Regards,
Tim

0 Ambreesh Tripathi over 6 years ago

TI__Expert 6860 points

Michel ,

Please use the design calculator given in product folder here .

http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=slvc452&fileType=zip

You shoudl be able to calculate compensation components easily by using the design calculator .

---Ambreesh

0 Michel de Jongh over 6 years ago in reply to Ambreesh Tripathi

Prodigy 55 points

Ambreesh Tripathi said:

Michel ,

Please use the design calculator given in product folder here .

http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=slvc452&fileType=zip

You shoudl be able to calculate compensation components easily by using the design calculator .

---Ambreesh

Sorry for the late reply.

The results from this calculator are equal to our calculations. When the values are used in Webench, the results show that fco is too low.
Could this be an error in Webench or should we use another type of compensation instead?

Kind regards,
Michel

0 Michel de Jongh over 6 years ago in reply to Timothy Hegarty

Prodigy 55 points

Hi Tim,

Thank you for your reply.
For the calculations in the referred documents we miss the Se value in the datasheet. Is there a way to determine this value?
In the document Ambreesh referred to, this value is set to 1, but it is not used in any of the calculations.

Kind regards,

Michel

0 Michel de Jongh over 6 years ago in reply to Timothy Hegarty

Prodigy 55 points

0 Timothy Hegarty over 6 years ago in reply to Michel de Jongh

TI__Guru 72702 points

Hi Michel,

Se is the slope compensation value, but this only has a second order effect on the bode plot, particularly if the crossover frequency is less than 10% of switching frequency.

See more info here: www.how2power.com/pdf_view.php

Regards,
Tim

0 Michel de Jongh over 6 years ago in reply to Timothy Hegarty

Prodigy 55 points

Hi Tim,

Thank you for the support.

Kind regards,
Michel

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WEBENCH® Tools/TPS54360B-Q1: Compensation with low ESR aluminium capacitor