SN74LVC8T245: What happens if OE pin is unconnected on the SN74LVC8T245DBQR?

Juan Ocampo

Intellectual 385 points

Part Number: SN74LVC8T245

What happens if the OE pin is unconnected? Is there an internal pull up or pull down?

over 5 years ago

0 Clemens Ladisch over 5 years ago

Guru 316440 points

OE must be connected; see footnote (3) in section 8.3.

0 Juan Ocampo over 5 years ago in reply to Clemens Ladisch

Intellectual 385 points

So, we have had this circuit with OE left floating for years and had never had an issue, but we are now experiencing some intermittent issues with our device that may be caused by this potentially. If it is good most of the time, but every once in awhile it enters the isolation state then this could be causing our problems.

0 Karan Kotadia over 5 years ago in reply to Juan Ocampo

TI__Genius 16735 points

Hi,

You are leaving a CMOS input floating which is against recommended operating conditions. [FAQ] How does a slow or floating input affect a CMOS device?

There is no guaranteed state of what that pin will be since it is floating. We recommend using a weak pulldown on the OE pin to avoid this issue.

Thanks!

-Karan

Logic

Logic forum

SN74LVC8T245: What happens if OE pin is unconnected on the SN74LVC8T245DBQR?