SN74LVC16T245: DIR Change while OE is active

Nir Flysher

Expert 3367 points

Part Number: SN74LVC16T245
Other Parts Discussed in Thread: SN74LVCH16T245

Dear Team,

Can you please see below question from my customer ?

They are using SN74LVC16T245 ( in BGA microstar package) - SN74LVC16T245ZQLR.

We have noticed that during changing DIR while OE is active , the output generates a small glitch lasting about 5ns.

Is it normal?

2. Should I expect the same behavior with the bus hold version of that device - SN74LVCH16T245?

Best regards,

Nir.

over 7 years ago

0 ShreyasRao over 7 years ago

TI__Guru 62240 points

Nir,

Any glitch according to me is not normal. Is there a possibility to have the OE disable the IO ports while the DIR change?

0 Nir Flysher over 7 years ago in reply to ShreyasRao

TI__Expert 3367 points

Dear Shreyas,
Thanks for the quick answer.
We're trying to avoid or mitigate this glitch.
From your question it implies that if the OE is disable before the DIR change there will not be a glitch.
Is it correct ? Can you please explain ?

Best regards,
Nir.

0 ShreyasRao over 7 years ago in reply to Nir Flysher

TI__Guru 62240 points

Hi Nir,

Yes, disabling the OE pin is safe way to avoid the glitch as the ports are tristated and once the DIR is changed, the OE can be enabled.

If you can send the scope shot with glitch, DIR change, A and B port signal at that instant, will be helpful for review.

Logic

Logic forum

SN74LVC16T245: DIR Change while OE is active