TXS0108EPWR to interface FPGA output to DA-converter 50MHz 1.8V to 3.3V

Oliver Rubinke1

Prodigy 30 points

Other Parts Discussed in Thread: TXS0108E, SN74AXC8T245, SN74AXC4T774

Dear Sir or Madam,

I'd like to interface from 1.8V to 3.3V domain using the TXS0108EPWR.

I assume a maximum frequency of f_max = 50MHz.

The AD-converter I intend to control is a AD5541.

Will the TXS0108EPWR a good choice to do this job?

Are there any alternative parts for this case?

There are no pullup nor pulldown resistors inbetween TXS0108 output and the AD's inputs.

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 317370 points

The TXS does not work with pulldowns.

What are the directions of the signals?

0 Michael J Schultis over 4 years ago in reply to Clemens Ladisch

TI__Mastermind 24985 points

Hello Oliver,

If you need 50MHz operation, TXS0108E is not going to be the recommended device.

Clemens asked about the directionality of the signals and this is critical to a proper device recommendation.

If all the signals are fixed direction, and do not need to be automatically bidirectional, then the SN74AXC8T245 could work, or based on the exact combination of the directions of the signals, maybe 2x SN74AXC4T774 would be a better option as each channel has individual direction control.

And these devices can support the 50MHz requirement that you are targeting.

Best,
Michael

0 Oliver Rubinke1 over 4 years ago in reply to Clemens Ladisch

Prodigy 30 points

Hi,

the signals' direction is from A to B

All signal have the same direction.

Oliver

0 Oliver Rubinke1 over 4 years ago in reply to Michael J Schultis

Prodigy 30 points

Thank you for your answer.

I have to come up with a question regarding the

SN74AXC8T245PWR

it is regarding the direction pin settings.

Assuming VCCA is 1.8V and VCCB is 3.3V what would be the right voltage level on those two pins when my desired direction is from A to B?

Both VCCA and VCCB are above 1.4V.

regarding the following table I need to tie /OE to and DIR2 to GND wherby DIR1 has to be tied to 1.8V in order to set all channels to direction A to B.

Am I right?

0 Clemens Ladisch over 4 years ago in reply to Oliver Rubinke1

Guru 317370 points

Yes, OE and DIR2 must be low, and DIR1 must be high (1.8 V or 3.3 V).

Logic

Logic forum

TXS0108EPWR to interface FPGA output to DA-converter 50MHz 1.8V to 3.3V

SN74AXC8T245PWR