TMS320F28377D: ibis driver models

Part Number: TMS320F28377D

I have a question about IBIS models. I downloaded sprm637a.ibis for modeling the 28377d ZWT package.

I've noticed that the BCF3335DSHYPBFZ device using the BCF3335D_DRIVER_MODE model tends to ring more than other 28377d device models and that the pins that use this model are external memory interface data pins. Let's say I use one of these pins but I'm using it as a GPIO output (i.e. I'm not using as an external memory interface and am not configuring it as a boot mode data pin). Even though I'm not configuring as boot mode I should still use the BCF3335DSHYPBFZ model? Or would one of the other device driver models be more suitable since I'm using it as a GPIO?

Thank you.

over 5 years ago

0 Peter Galicki over 5 years ago

TI__Expert 8105 points

Hello,

I have forwarded your question to an IBIS specialist, should be getting back to you early next week

Regards,
PEter

0 Peter Galicki over 5 years ago in reply to Peter Galicki

TI__Expert 8105 points

Hello,

The IBIS model for the device is independent of the application scenario. They are generic. As long as it is used as driver (irrespective of external memory interface), these models are fine.

Can you tell me the design names of the devices being discussed please

Regards,

PEter

0 rs over 5 years ago in reply to Peter Galicki

Intellectual 891 points

I'm using TMS320F28377DZWT device and sprm637a.ibs ibis file.

I'm simulating GPIO70 which corresponds to the BCF3335DSHYPBFZ model in the ibis file. I just want to confirm that is the right model to use. I notice this model tends to ring more than other models for other pins. I will avoid pins that use this model or add a series resistor if there's room.

0 Peter Galicki over 5 years ago in reply to rs

TI__Expert 8105 points

Hi,

I have contacted a specialist in this area with your question, should be hearing back soon

Regards,

PEter

0 Peter Galicki over 5 years ago in reply to Peter Galicki

TI__Expert 8105 points

Hello,

Sorry for the delay, I am still waiting to hear from the IBIS specialist on this

REgards,
Peter

0 Peter Galicki over 5 years ago in reply to Peter Galicki

TI__Expert 8105 points

Hi,

BCF3335DSHYPBFZ maps to GPIO70 in F2837x. This is high driver buffer and also can experience impedance mismatch and noise is expected. To avoid, series resistance termination (around 20 ohms) would help to address noise issues. Whereas BCF183350CSHYPBFZ_7LM is of low drive and circuit shown has better impedance mismatch and hence less noise expected.

Regards,

PEter

0 Peter Galicki over 5 years ago in reply to Peter Galicki

TI__Expert 8105 points

A small typo in my previous reply - the "impedance mismatch" in the last sentence should say "impedance match". Here is the entire correct reply:

Regards,
PEter

0 Peter Galicki over 5 years ago in reply to Peter Galicki

TI__Expert 8105 points

One more comment, please take a look at the Signal Description Table 4-1 on page 41 of the datasheet. Specifically, just below the table there are 3 notes. Note 3 recommends a 39 Ohm resistor vs 20 Ohms in my response above. Please go with the 39 Ohm resistor.

Regards,
Peter

0 rs over 5 years ago in reply to Peter Galicki

Intellectual 891 points

I hadn't noticed that footnote before so thanks for pointing that out.

0 Peter Galicki over 5 years ago in reply to rs

TI__Expert 8105 points

Hi,

I am going to close this post now, please do not hesitate to re-open if you have additional questions.

Regards,
PEter

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TMS320F28377D: ibis driver models