TXB0108: if shifting only 7 channels, what to do with the last 2 pins?

Thomas Bewley

Expert 1030 points

Part Number: TXB0108

I want to use the TXB0108 to shift 7 channels. Should I tie A8 to GND and leave B8 open, or do something else?

over 5 years ago

0 Dylan Hubbard over 5 years ago

TI__Mastermind 46295 points

Hey Thomas,

This FAQ should help you out here: https://e2e.ti.com/support/logic/f/151/t/788628?tisearch=e2e-sitesearch&keymatch=faq%3Atrue

0 Thomas Bewley over 5 years ago

Expert 1030 points

Thank you for the link to this FAQ. Follow up: it now looks like we have 2 channels we will not use. Can I tie all four of the unused channels (A7, A8, B7, B8) together, and then through a single 100k resistor to ground, or do I need 4 separate 100k resistors, one for each unused pin? The latter solution seems pretty excessive. What is the reasoning for requiring this resistor at all?

0 Dylan Hubbard over 5 years ago in reply to Thomas Bewley

TI__Mastermind 46295 points

Hey Thomas,

The added resistors are more of a precaution to keep a valid logic state at the I/O in any scenario. You can combine them, however i still recommend using a separate resistor for the A and B sides.

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TXB0108: if shifting only 7 channels, what to do with the last 2 pins?