SN74AUP1T34: How to determine output rise and fall times

marq qram

Part Number: SN74AUP1T34
Other Parts Discussed in Thread: SN74AXC1T45

Hello,

This part doesn't specify rise and fall times under any loading conditions. It seems that way for most parts in this product line, so I must be misunderstanding something about the fundamental use of these components. Given an input rise/fall time and knowing my loading conditions of the buffer, how do I determine what output rise/fall times I can expect from this component? Additionally, how can I determine if a given TI logic device is suitable for a given I/O frequency?

My specific use case for this part is:

Input voltage= 1.8V
Output voltage= 3.3V
Input rise/fall times= 5ns
Output load= 15pF

Thanks

over 5 years ago

0 Emrys Maier over 5 years ago

TI__Guru* 96591 points

Hi Marq,

For buffered logic devices (like the SN74AUP1T34), the input edge rate is relatively insignificant to the output edge rate. This is due to the huge gain from input to output.

There's an FAQ that goes into some detail on how to estimate the output transition rate of a device located here:

There's also an FAQ that covers the data rate for common logic devices, although it's not quite as straight-forward for translation devices:

If you need additional assistance, please let me know.

0 ShreyasRao over 5 years ago

TI__Guru 56070 points

Hi Marq,

What is the IO frequency of operation? Is this unidirectional level translation only?
We have also released the new SN74AXC1T45 device which supports up to 500Mbps; 1.8 to 3.3V with 12mA drive strength.

0 marq qram over 5 years ago in reply to ShreyasRao

Prodigy 40 points

Thanks. The frequency is very low, so the original component selection should be sufficient, but I'll check out the part you suggest.

Logic

Logic forum

SN74AUP1T34: How to determine output rise and fall times