SN74LVTH244A: Pullups and Pulldowns on Data Lines

Sean Iwasaki

Part Number: SN74LVTH244A
Other Parts Discussed in Thread: SN74LV244AT, SN74LVC541A

Dear Community::

A related question was posted regarding the "not recommend" notation in page 2 of the data sheet, but I would like further clarification.

For a point-to-point hot swap application , where one (1) SN74LVTH244a output driver connected to one (1) SN74LVTH244A input receiver, can I used pullups and pulldowns on the outputs and/or inputs on the data lines?

Some data lines are static (card address slot information , card presence, interrupt, etc) and some data lines are dynamic (PWM logic control signals).

Thanks

Sean

over 2 years ago

0 Emrys Maier over 2 years ago

TI__Guru* 96712 points

Hi Sean,

If you are connecting the output of one SN74LVTH244A to the input of another SN74LVTH244A, then the bus-hold circuit will be actively driving the line. The purpose of these is to eliminate the need for pull-up or pull-down resistors.

If you need to set default states with pull-x resistors, then I would recommend using a non-bus-hold device such as SN74LV244AT.

0 Sean Iwasaki over 2 years ago

Intellectual 390 points

Emrys:

Thank you so very much for your quick response and recommendations. I greatly appreciate.

Sincerely

Sean

0 Sean Iwasaki over 2 years ago in reply to Sean Iwasaki

Intellectual 390 points

Emrys:

The SN74LV244At is 5V only. Our backplane bus logic voltage is 3.3V and PCB routing complex, can we use SN74LVC541A?

Thanks

Sean

0 Emrys Maier over 2 years ago in reply to Sean Iwasaki

TI__Guru* 96712 points

Hi Sean,

Yes, SN74LVC541A would work well for 3.3V. There's actually a lot of options at that voltage, depending on exactly what you're after.

0 Sean Iwasaki over 2 years ago in reply to Emrys Maier

Intellectual 390 points

Emrys:

Thank you so very much again.

Sincerely

Sean

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SN74LVTH244A: Pullups and Pulldowns on Data Lines