SN74LVC8T245: how to understand "Input transition rise or fall rate" on SN74LVC8T245

lin huang

Part Number: SN74LVC8T245

In SN74LVC8T245 ,Input transition rise or fall rate is showed below, as my case,VCCI=1.8V,that is to say the max rise time is 1.8*20=36ns? If the rise time of the signal into the part is 80ns，what will happen to the part？

1、 the output will not follow the input？

2、 The part will get hot？

over 5 years ago

0 ShreyasRao over 5 years ago

TI__Guru 58990 points

Hi Lin,

Please look into the slow and floating CMOS input app note
www.ti.com/.../scba004d.pdf

There is another app note about the issues with slow inputs and mitigating with schmitt trigger inputs.
www.ti.com/.../slla364a.pdf

It probably wont be noticeable with 80ns as compared to 36ns recommended.

0 lin huang over 5 years ago in reply to ShreyasRao

Prodigy 210 points

thanks for your reply，my data rate is 1Mbps，I will use only 4 channel，if the risk can be ignore，and how can i calculate the Dynamic power consumption？

0 ShreyasRao over 5 years ago in reply to lin huang

TI__Guru 58990 points

Hi Lin,

Please refer to the app note on power dissipation:
www.ti.com/.../scaa035b.pdf

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SN74LVC8T245: how to understand "Input transition rise or fall rate" on SN74LVC8T245