TPS562201: Capacitor at Vout

Shunsuke Nagata

Genius 12740 points

Part Number: TPS562201

Hi,

User's guide for TPS562201EVM shows below schematics

Could you please support below questions?

1. What is meaning of C8?
2. How to calculate C8?

Regards,
Nagata.

0 Shawn Nie over 5 years ago

Hi Nagata,

C8 is the feedforward capacitor, it is used to increasing bandwidth and phase margin. You can refer to below application note.

Shawn

0 Shunsuke Nagata over 5 years ago in reply to Shawn Nie

Hi, Shawn,

Thank you very much for your supports.

Could you please let me confirm which formula should be useful for feedfoward capacitor?

I believe the (6) formula in page7 of you application note is useful for the calculation. Is it correct?

Regards,
Nagata.

0 Shawn Nie over 5 years ago in reply to Shunsuke Nagata

Hi,

You can refer to Equation (14) or below file. It is more easier.

But It is better for you to select the value between 50pF -150pF. Also you can remove this capacitor, it is not required.

Shawn

0 Shunsuke Nagata over 5 years ago in reply to Shawn Nie

Hi, Shawn,

I calculate the cf value for TPS562201EVM as trial.

The result is 0.16pF but the board uses 10pF. How did you calculate the 10pF for EVM?

Regards,
Nagata.

0 Shawn Nie over 5 years ago in reply to Shunsuke Nagata

Hi Nagata,

f_noCff is the crossover frequency without Cff, it not the value which is calculated by equation (5). And I think 10pF is not the appropriate value.

Shawn

Power management forum