SN74LVC16T245: Series Resistors

Wagner Silva

Part Number: SN74LVC16T245

Hi Team,

I need to translate from 3.3V to 5.0V. I have found some schematics using pull up/down resistors on inputs/outputs. I've found some others schematics using a low resitors(like 22R) in series with inputs/outputs.

My question is, Is really a need to use these resistors in design? If yes, when use them?

Regards.

over 3 years ago

0 Emrys Maier over 3 years ago

TI__Guru* 96591 points

Hello, and welcome to the forums!

Pull-up and pull-down resistors are used to hold the voltage on the trace either high or low (respectively) when the device has its outputs disabled or when it is powered off. The reason for this is to prevent floating voltage nodes, which can produce problems. Two of the problems that can occur are discussed in this FAQ: https://e2e.ti.com/support/logic/f/151/t/737694

Series resistors at the output are generally used when transmitting over transmission lines into a high-impedance load. There's an FAQ that goes into details of the effects here: https://e2e.ti.com/support/logic/f/151/t/763609

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SN74LVC16T245: Series Resistors