74LVT245, can I use it this way...

Status
Not open for further replies.
A

aleksaZR

Newbie level 6
Joined
Mar 29, 2008
Messages
11
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,364
Hi all,

At first, I wanted to use '245 to convert 5V signals to 3V3, uni-directional, direction A to B.
Input signals may be floating, so I've added 10k pull ups to 5V on side A of '245.

Now I need it to be bi-directional, but I don't know if the 5V pull ups will harm the 3V3 outputs on side A?
In this datasheet, where can I find that information?
 

It should be safe and you probably don't need the pull-up resistors. The critical factor is that the pins can withstand 5V while the device is tri-state but you have it permanently enabled anyway. Note that it will not convert from 3.3V and 5V though. A 5V on the 'A' side will be converted to 3.3V on the 'B' side but going the other way, 'B' will come out on the 'A' side at 3.3V. That may not be a problem as it would still meet normal TTL level specifications for a logic high and low.

Brian.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…