TXB0304: ibis model

Lidar Glazer

Part Number: TXB0304

hi,

When simulate TXB0304 i see unreasonable behavior with 40MHz signal with 10cm transmition line load in series and 1pF capacitance to ground (even with series termination).

Can i please get assistance in understanding the issue?

thanks

Lidar

over 8 years ago

0 Emrys Maier over 8 years ago

TI__Guru* 97666 points

Hi Lidar,
Can you show images of your schematic and simulation output?

0 Lidar Glazer over 8 years ago in reply to Emrys Maier

Prodigy 90 points

TXB0304_ibis_Q.docx

0 Lidar Glazer over 8 years ago in reply to Lidar Glazer

Prodigy 90 points

I attached a doc file with the data.
thanks!

0 Emrys Maier over 8 years ago in reply to Lidar Glazer

TI__Guru* 97666 points

Thanks Lidar,
Do you also have the MSub1 substrate details? I didn't see it in the attached document.

I want to see if I can replicate the issue in my own simulator.

0 Lidar Glazer over 8 years ago in reply to Emrys Maier

Prodigy 90 points

TXB0304_ibis_Q_1.docx

i updated the doc with all the info

0 Emrys Maier over 8 years ago in reply to Lidar Glazer

TI__Guru* 97666 points

Thanks,
I'll take a look.

0 ShreyasRao over 8 years ago

TI__Guru 63860 points

Hi Lidar,

It may be something to do with the software you are using.

I used the Hyperlynx s/w and captured this waveform under similar conditions. The signal integrity is much better compared to your simulations.

I found that the model of the TXB0304 had 2 parts. one with the one-shot and another without it.

we need to include both the models together to make it work as shown below.

The loading is 50k, and 1pF, with the trans line with 75Zo and 0.5ohm resistance. The signal goes to 1.8V at 40Mhz.

I have a scope shot with me for testing a 1.8 to 3.3V translation using TXB0304 at 1Mhz as attached. There were no loading except for the probes which might contribute ~20pF overall.

0 Lidar Glazer over 8 years ago in reply to ShreyasRao

Prodigy 90 points

thanks. indeed using one shot model solved the issue.
i used it only (without using the two models together as you suggested and it worked properly)
can you please explain what "one-shot" means?
why do i have to use the two models together?
thanks!

0 ShreyasRao over 8 years ago in reply to Lidar Glazer

TI__Guru 63860 points

Lidar,

One-shot circuitry are edge rate acceleration circuitry intended for momentarily speeding up the rising / falling edge of the signal to the Vccx level.

They are active for 10-20ns or when the signal reaches to about 90% of the Vccx level.

I believe that the models were separately developed, one with only oneshot behaviour and one without oneshot behavior.

some of the other models have them combined inside.

Logic

Logic forum

TXB0304: ibis model