TPS7A39: PDN model.

Fabio Posser

Prodigy 195 points

Part Number: TPS7A39

Tool/software:

Hi,

I'm using the LDO TPS7A39 and I would like to simulate my PDN with Ansys Siwave.

Where I need to add the resistance and inductance of the Source, ESL ESR.

Which values should I use for this device to have accuracy on the characteristics?

Thank you.

4 months ago

0 Nick Butts 4 months ago

TI__Mastermind 44385 points

Hi Fabio,

Fabio Posser said:
Where I need to add the resistance and inductance of the Source, ESL ESR.

Are you asking for the input voltage source?

Thanks,

Nick

0 Fabio Posser 4 months ago in reply to Nick Butts

Prodigy 195 points

Hi Nick, in fact I was asking about the output model of it to not consider the LDO on the simulation as a perfect voltage source.

But if you have information about the input requirements of it would be very usefull also.

0 Nick Butts 4 months ago in reply to Fabio Posser

TI__Mastermind 44385 points

Hi Fabio,

The output impedance should already be modeled so you don't need to add it externally. There aren't direct input source impedance requirements so I can't provide guidance on that.

Regards,

Nick

0 Fabio Posser 3 months ago in reply to Nick Butts

Prodigy 195 points

Hi Nick, I'm not talking about Spice simulation with the model.

I'm trying to do a PDN simulation with Ansys Siwave, that's why I asked the device characteristics.

0 Nick Butts 3 months ago in reply to Fabio Posser

TI__Mastermind 44385 points

Hi Fabio,

Got it. I think the best path would be to take an output impedance measurement on the bench and then you can model it how you think fits best. The output impedance is not generally well-approximated by a first-order model, so seeing it for yourself will be helpful. The output impedance is highly dependent on the load, so I will need the loading condition, and the output capacitor as well. Also what is your input/output voltage condition?

Thanks,

Nick

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TPS7A39: PDN model.