SN74LVC8T245: Looking for bidirectional bus buffer

Shinya Sawamoto

Part Number: SN74LVC8T245
Other Parts Discussed in Thread: SN74AVC4T774

Hello team,

I'm looking for a bidirectional bus buffer like SN74LVC8T245 but want to have auto direction control.
- for 6bit SPI
- 3.3V rail (not required level translation)
- with long trace such as board to board communication
Could you give your advice which devices are recommended for this use case?

Thanks in advance.
S.Sawamoto

over 6 years ago

0 Clemens Ladisch over 6 years ago

Guru 317000 points

Automatic direction control requires that the external devices are able to override the voltage level at the translator's outputs; in other words, the translator cannot have strong output drivers.

So it is not possible to have buffers with automatic direction sensing.

If your Quad SPI devices do not have output drivers that are strong enough, they cannot be used over a long connection.

0 Shinya Sawamoto over 6 years ago in reply to Clemens Ladisch

TI__Expert 5285 points

Thanks, I understood there is no automatic bidirectional buffer solution.
How about controlled bidirectional buffer solution?

0 Clemens Ladisch over 6 years ago in reply to Shinya Sawamoto

Guru 317000 points

Then you have to provide a direction signal, and to use direction-controlled translators or transceivers. 4-line SPI typically uses the SN74AVC4T774 because it has direction controls for each line; all other devices provide multiple lines in the same direction, so you have to use at least two chips.

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SN74LVC8T245: Looking for bidirectional bus buffer