SN74AXC4T774-Q1: SN74AXC4T774-Q1 IBIS model

Which pin model did you use? I did not see anything unusual in the 1.8 V model (io_1p8_y).

I am using the below models for my simulation:

io_1p8_x for 3.3V to 1.8V

io_3p3_y 1.8V to 3.3V.

Hello Sathish,

Please allow us some time to look into this. Thanks!

Regards,

Josh

Sure..But please do reply us within this week as we there are some deliverables ON-HOLD due to this.

Thanks,

Sathish Raja C

Hello Sathish,

Thank you for your understanding.

Regards,

Josh

Hello Sathish,

Thank you for your understanding.

Regards,

Josh

Hi Joshua,

Any update on the above issue faced.

Currently the model is rated for 130C @slow corner can we get the model for 100C.??

...

Do provide your response ASAP.

Thanks and regards,

Sathish Raja C

Hello Sathish,

Apologies again for the delay. After trying different IO models, I am not able to replicate the waveforms your shared. Below is the waveform for the io_1p8x model. Can you share the components connected to the output?

As for 100C for Slow PVT, unfortunately we won't be able to provide this at this time.

Regards,

Josh

Hi Joshua,

Attached are the IBIS model of TX (saa-tc4d9xe-20mf500.ibs) and RX (m70a_spi_aat.ibs)

m70a_spi_aat.ibssaa-tc4d9xe-20mf500.ibs

Below is the topology of SPI for ref

Thanks and regards,

Sathish Raja C

Hello Sathish,

We are taking a look at this and will provide an update by EOD Friday. Thanks!

Regards,

Josh

Hello Sathish,

Similar as before, I have not been able to replicate the issue. Waveform captures when AXC output is connected to the NAND Flash input (CS) is normal. Additionally, I have not seen this issue (heavy undershooting) on actual silicon before. 

Regards,

Josh

Hi Joshua,

Can we have a call to discuss on the issue faced by us.

Do setup a teams call considering IST zone.

Or do provide a convenient time will setup a call.

Thanks and regards,

Sathish Raja C

While ringing is possible, it is not possible for this device to generate a DC voltage below GND. So this must be a problem with the simulation, not with the real device.

Please specify which IBIS simulation software you're using, and how exactly you have configured the load at the output pin.

Adding yannick RENAUD 

Hello Sathish,

I agree with Clemens here, please provide a visual on how the output pins are configured. Load capacitance, transmission line impedance, transmission line delay and so on can impact the output signal and cause ringing.

Regards,

Josh 

hello 

please to find my configuration under  ansys Desktop  version2022R2

the simualtion is done without load with the gate but in the three modes Typical / Slow / Fast

ID 443  in typical; ID 444 in Fast  ; ID 445 in slow

Without load :

the results get are the following 

With load of 10pF:

regards

Yannick

Hello Yannick,

A 10pF load capacitance is very common and shouldn't be causing heavy undershoot. You have "io_1p8_x" model but what pin are you using?

ADS is the software program we use and I'm able to select pins and models.

Regards,

Josh

Hello Joshua

i am sorry.  With Ansys'  desktop    we can also select the model in these simulations. We used this confg  ip8_x in the three modes :

IO_

Regrads 

Yannick

Hello Yannick,

I went ahead and changed the component and pins to match your settings. However, I still was not able to replicate the waveforms you showed us.

Is there more to the IBIS model (ID=443) you shared? The IBIS model I get when using ADS looks something like this: 

Can you share how you are referencing this IBIS model?

Regards,

Josh

Hello Joshua,

I don't have other element I can share because there isn't other elements like ADS.

For the reference, i can't change it, So i assume  it is GND.

I made the same test on Hyperlynx and I got the same results that you. so it is probable that the error from ansys.

regards 

Yannick