TPS62097: Feed forward capacitor

jacob harif

Part Number: TPS62097

Hy I would like to add FF cap ( working with the non-fixed IC ) . I understand that the IC is likely more a VOLTAGE MODE operation and not like HYSTERESIS operation, so I wish to ask what is the limit of the FF cap : Is it ok to put a 22nF for example ?

Thanks a lot - Jacov

over 8 years ago

0 Chris Glaser over 8 years ago

TI__Guru**** 150880 points

On page 13 of the D/S, it is noted that a feed forward cap is not required. You can add one if you wish, but it may not improve anything. Why do you wish to add one?

This app note describes the Cff value in relation to the FB resistors: www.ti.com/.../slyt469.pdf

This app note describes the control topology: www.ti.com/.../slyt531.pdf

0 jacob harif over 8 years ago in reply to Chris Glaser

Prodigy 30 points

Thanks for the answer !!

I do wish to add a FF cap to cause the loop being WORSER .

Then I am going to use the BODE 100 Network Analayzer and find out if the tool can show me that the IC loop gain is bad .

Thank you !!

Jacov

0 Chris Glaser over 8 years ago in reply to jacob harif

TI__Guru**** 150880 points

Ah, this is quite an unusual use of the Cff.

DCS-Control is quite stable, as shown in this app note with the wide allowed output filter range: www.ti.com/.../slva710.pdf

0 jacob harif over 8 years ago in reply to Chris Glaser

Prodigy 30 points

Thanks so much !

So I am going to measure the Loop Response with Network Analyzer and compare it to Fig. 3 at the User Guide SLVUA15 TPS62097EVM : but I DO NOT KNOW WHAT IS THE OUTPUT VOLTAGE AT THAT fig. 3 .

Thank you for advise the output voltage at that measurement !

Jacov

0 Chris Glaser over 8 years ago in reply to jacob harif

TI__Guru**** 150880 points

It is a measurement of the EVM, which is set to output 1.2V.

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TPS62097: Feed forward capacitor