TPS51367: Cap selection C1/Cslew

Marion Loessl

Part Number: TPS51367

Hi,

which value would you recommend for the following requirements:

Somehow the both calcs in the datasheet:

Seem to contradict each other for the cap selection.

Can you help and recommend a value?

Does C1 have a direct influence on the compensation network? Will the converter be slower or faster?

Or will the regulation behavior be stable under the above conditions only dependent on C_C1, C_C2, R_C1, R_C2?

Thanks for your quick help,

Marion

0 Yuchang Zhang over 4 years ago

Hi, Just cal. the SS time based on the Vout in your application to choose a proper Cslew, and recommend the value >2.7nF.

Yuchang

0 Marion Loessl over 4 years ago in reply to Yuchang Zhang

Hi Yuchang,

thanks for your quick answer.

the required SS time is as I wrote 1.8ms. So you say, with anything greater 2.7nF, like f.e. 10nF, my application would work?

Also for 800kHz fsw?

Can you help me answer the above questions:

Does C1 have a direct influence on the compensation network? Will the converter be slower or faster?

Or will the regulation behavior be stable under the above conditions only dependent on C_C1, C_C2, R_C1, R_C2?

Kind regards,

Marion

0 Yuchang Zhang over 4 years ago in reply to Marion Loessl

Hi Marion,

Yes, >2.7nf is to ensure the EA work well.

Soft-start time depends on Vout, not related to Fsw, suppose Vout=1V, if need 1.8ms soft-start, you can use 18nf Cslew.

And you can think no influence for others.

Yuchang

0 Marion Loessl over 4 years ago in reply to Yuchang Zhang

Hi Yuchang, what do you mean by EA?

Kind regards, Marion

0 Yuchang Zhang over 4 years ago in reply to Marion Loessl

Hi Marion, sorry typo. Should be gm amplifier.

Yuchang

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