SN75LVDT388A: Is the IBIS model correct for the SN75LVDT388A

Matthew MacDonald1

Part Number: SN75LVDT388A

I am running a Hyper lynx simulation using the SN75LVDT388A LVTTL output to the input of a Nexperia 74LVC594AD. I am finding that a higher frequencies (72MHz), the pulse is not reaching its logic low level ( the duty cycle approaches 90%). If I switch the SN75LVDT388A IBIS model for a DS90LV028ATM IBIS model, the duty cycle is at 50%. Any idea why the duty cycle changes with frequency when using the SN75LVDT388A IBIS model? The SN75LVDT388A is rated to 250Mbps(125MHz). I also noticed that the rise and fall times are delayed on the SN75LVDT388A IBIS model.

results:

SN75LVDT388A:

DS90LV028ATM:

Falling edges:

DS90LV028ATM (earlier waveform) vs SN75LVDT388A IBIS (driver is red, load is green)

over 7 years ago

0 Matthew MacDonald1 over 7 years ago

Prodigy 90 points

0 Matthew MacDonald1 over 7 years ago in reply to Matthew MacDonald1

Prodigy 90 points

0 Matthew MacDonald1 over 7 years ago in reply to Matthew MacDonald1

Prodigy 90 points

0 Yaser Ibrahim over 7 years ago in reply to Matthew MacDonald1

TI__Genius 10250 points

Hello Matthew,

I will check this and get back to you.

Regards,
Yaser

0 Yaser Ibrahim over 7 years ago in reply to Yaser Ibrahim

TI__Genius 10250 points

Hello Matthew,

Sorry for the delay. This model is really old and the reason you were not able to run simulation at a higher frequency is the result of the excessive delay in rising and falling VT waveform. In addition, the delay amount is not symmetric between rising and falling waveform, so this results in a distorted duty cycle number. The attached file should solve the problem. Please try it and let us know how it works for you.

Regards,

Yaser

lvdt388a.ibs

0 Matthew MacDonald1 over 7 years ago in reply to Yaser Ibrahim

Prodigy 90 points

Hi

The new file resolved my issue.

Thanks

Matthew MacDonald

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SN75LVDT388A: Is the IBIS model correct for the SN75LVDT388A