SN74LVT16244B: Pull Up resister and BUS HOLD

David Zhao

Part Number: SN74LVT16244B
Other Parts Discussed in Thread: SN74LVTH16244A

For SN74LVT16244b, what pull up value should use for input? When use 10kohm to pull up, output is low. But when use 2kohm to pull up, output is high. How to calculate the value?

Also SN74LVT16244B should have bus hold function. Any doc that introduce detail of this function? Thanks!

Regards

David

over 7 years ago

0 Clemens Ladisch over 7 years ago

Guru 261460 points

Are you using the SN74LVT16244B or the SN74LVTH16244A? Only the latter has bus-hold inputs.

0 Emrys Maier over 7 years ago

TI__Guru* 96681 points

Hi David,
The SN74LVT16244B does not have the 'bus hold' feature, however the SN74VLTH16244A does have that feature.

Can you tell me more about the circuit surrounding this? Is the input _only_ connected to the SN74LVT16244B? Did you possibly mean the LVTH version?

0 David Zhao over 7 years ago in reply to Emrys Maier

TI__Intellectual 1820 points

Hi Emrys
Thanks for your reply! I have confirmed with customer. The part number is SN74LVTH16244ADGG. So it is LVTH version. So any hold bus description about SN74LVTH16244A and what pull up resister should be used?
Regards
David

0 Emrys Maier over 7 years ago in reply to David Zhao

TI__Guru* 96681 points

We don't recommend using pull-up or pull-down resistors with bus-hold devices if you can avoid thm. If you have to use one, they can be used if they can supply enough current to overdrive the bus hold latch (>~500ua).

A 6.6k resistor will put you right at 500ua for a 3.3V supply - so anything smaller than that should work.

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SN74LVT16244B: Pull Up resister and BUS HOLD