TPS53355: Calculation of feedback resistors during smartreflex

Madhu Sharma

Part Number: TPS53355
Other Parts Discussed in Thread: LM10011, , LM21215A

Hi,

I am using TPS53355 for generating variable core voltage ( smart reflex) for keystone-II device. LM10011 is used as DAC.

Please suggest me if there is any document which describes selection of feedback resistors ( R1 & R2) in this case.

Thanks & Regards,

Madhu

over 8 years ago

0 JohnTucker over 8 years ago

TI__Guru**** 191445 points

I think the LM10011 datasheet has everything you need to know to calculate the resistor values:
www.ti.com/.../lm10011.pdf

0 Madhu Sharma over 8 years ago in reply to JohnTucker

Expert 2915 points

Hi John,

Thanks for the information.

The datasheet of LM10011 has equations while using LM21215A regulator. Also, the GUI (present in the link: t www.ti.com/product/LM10011 ) uses the same regulator LM21215A. Please let me know whether the same formulas can be applied to TPS53355 also.

Regards,
Madhu

0 JohnTucker over 8 years ago in reply to Madhu Sharma

TI__Guru**** 191445 points

Yes. Even VFB is the same for TPS53355... 0.6V.

0 Madhu Sharma over 8 years ago in reply to JohnTucker

Expert 2915 points

Hi John,

I am using ripple injection circuit. So for calculating, whether can i consider same 0.6V as VFB?
Because the datasheet gives different formula for calculating VFB when ripple injection is used ( equation 14).

Regards,
Madhu

0 JohnTucker over 8 years ago in reply to Madhu Sharma

TI__Guru**** 191445 points

Yes, go ahead and include that offset.

0 Madhu Sharma over 8 years ago in reply to JohnTucker

Expert 2915 points

Hi,

Thanks for answer.

Actually , the offset will slightly vary with output voltage. So I have calculated the offset for 1V and included that for calculation.
Please let me know is there any other better ways for the calculation.

Regards,
Madhu.

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TPS53355: Calculation of feedback resistors during smartreflex