DM3725: Error message during IBIS implementation

Yukiko Uemura

Part Number: DM3725

Hi,

One of my customer has been redesign their board to change from DM3725CBP to DM3725CUS due to LPDDR POP EOL.

They are trying a post layout simulation to LPDDR1 bus but received a following error message during IBIS implementation.

---------------------------------------------------------------------------------------------------------------------------------------
　[ERROR]Error : at line 258205 in file C:/sprm511.ibs : Messages for component am37xxcusnew:
　 ;; Error: minimum package inductance value (-3.6589e-011) is negative.
　 ;; Error: minimum package capacitance value (-6.48373e-013) is negative.
　Error : Parse failed on file C:/sprm511.ibs.
---------------------------------------------------------------------------------------------------------------------------------------

IBIS model is the one on TI website (AM/DM37x CUS IBIS Model, 04 Jun 2010), and OS is HyperLinx.

Could you please advise how my customer can fix this phenomenon?

over 4 years ago

0 Brad Griffis over 4 years ago

TI__Guru*** 125430 points

Yukiko Uemura said:
　[ERROR]Error : at line 258205 in file C:/sprm511.ibs : Messages for component am37xxcusnew:

I just looked at that file and line 258205 is the very last line of the file. It has only this:

[End]

I don't see any negative inductance values so it seems like this is an issue in the tool itself.

0 Yukiko Uemura over 4 years ago in reply to Brad Griffis

TI__Prodigy 50 points

I can see the exact same value in line43 (L_pkg) and line44 (C_pkg) of IBIS model. (underlined in red)

Are these Negative Inductance/Capacitance values not the cause to this error?

0 Brad Griffis over 4 years ago in reply to Yukiko Uemura

TI__Guru*** 125430 points

The AM37xx/DM37xx families of devices utilize an active feedback I/O cell in the SDRC. This cell is difficult to model in IBIS. The negative values shown are related to this active feedback I/O cell. It sounds like your simulation tool is not capable of working with these values. I recommend checking with your simulation vendor.

0 Hitoshi Sugawara over 4 years ago in reply to Brad Griffis

TI__Mastermind 18650 points

Hello Brad,

Thank you for your support.
According to the simulation vendor, unfortunately, they can not handle with our IBIS file.

The customer would like to clarify if the minus values are changed to plus values somehow and then simulate it.
Could you please let us know your observation.

Thank you again for your kind help.
Best regards,
Hitoshi

0 Brad Griffis over 4 years ago in reply to Hitoshi Sugawara

TI__Guru*** 125430 points

I do not recommend changing the model.

0 Hitoshi Sugawara over 4 years ago in reply to Brad Griffis

TI__Mastermind 18650 points

Hi Brad,

Thank you for the reply.
We understood that even though the values are minus, it is correct values for IBIS.

Best regards,
Hitoshi

0 Brad Griffis over 4 years ago in reply to Hitoshi Sugawara

TI__Guru*** 125430 points

Hitoshi,

Yes, that's correct.

Best regards,
Brad

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DM3725: Error message during IBIS implementation