VIO 1.8V to 3.3V or 5V

Hi everyone,

Thanks for taking the time to read this. I'm seeking some advice about
how to step up the GPIO signal voltage levels.

According to the data sheet the beagleboard outputs signals of
1.8/1.85V. I want to add an expansion board that can only accept
signals of either 3.3V or 5V.

The data sheet for the beagleboard also specifies that there is a VDD
pin of 5V that I can use to power my expansion board. Going on that
basis I assume I am better to buy a 5V version of my desired expansion
board. Would you agree?

What components are available that will allow me to step my data
signals from 1.8v to 5v and 5v to 1.8v? My expansion board requires bi-
directional communication to the beagleboard.

Again many thanks for your time and I look forward to reading your
responses.

Rob.

The Beagle uses TXS0102 devices for this purpose. I would look at the whole TXS or TXB series of bidirectional drivers from TI. There are 2,4 nas 8 bit versions of these devices

Gerald

Thank you Gerald, I will look into this.

Rob

Increasingly, I/O devices are 3.3V due to the power savings vs 5.0
volt versions. 5V uses about 50% more power than 3.3V which can add
up, especially when you are using batteries. So if you can get the I/O
devices you want in a 3.3V version, go with that.

Some 3.3V I/O buffers are tolerant of 5V signals. Here are some notes
for other products, but the general principles might be helpful:
http://jstamp.systronix.com/jstamp_pinout.htm
http://www.tstik.com/interfacing.html

We're looking at doing some Beagle interface products. Not sure what
yet until we get some experience with Beagle.

best regards

Bruce

bboyes wrote:

Increasingly, I/O devices are 3.3V due to the power savings vs 5.0
volt versions. 5V uses about 50% more power than 3.3V which can add
up, especially when you are using batteries. So if you can get the I/O
devices you want in a 3.3V version, go with that.

Some 3.3V I/O buffers are tolerant of 5V signals. Here are some notes
for other products, but the general principles might be helpful:
http://jstamp.systronix.com/jstamp_pinout.htm
http://www.tstik.com/interfacing.html

We're looking at doing some Beagle interface products. Not sure what
yet until we get some experience with Beagle.

I bet NXP has some stuff, too, given that this problem comes up all
the time with i2c...

b.g.