EN5339QI VRM Impedance in the PDN 2.0 Tool

[dkurgs]

Hello all,

it seems that the EN5339QI part in the PDN Excel Tool 2.0 for Cyclone 10 Gx devices has impossibly low VRM impedance.

The impedance seems to go between 1 to 10 mR from 1kHz to 10MHz, resulting in no necessary decoupling capacitors at all (Wouldn't that be great?)

Is this a known bug or are there correct VRM resistance and inductance values available?

Thanks!

[Mostafa_Intel_AE · Accepted solution]

Hello Dkurgs,

The VRM impedance for EN5339 is correct as 2.5mR to 10 mR from 1kHz to 10MHz.

It make sense that you don't need any decoupling caps(just the regulator default output caps 3x22uF required by default)  where based on the target impedance (100mR) the load step is very small which doesn't require any decoupling caps and the regulator closed loop will be able to achieved the required performance.

Please check EN5339 datasheet for transient performance at page 11 which shows very low voltage deviation.

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ds/en5339qi_06903.pdf

Thanks,

Mostafa