Output Impedance?

[ble0t]

How would one calculate the output impedance of something like this:

http://www.st.com/stonline/products/literature/ds/6573/74v1g70.pdf

Do you need to average the high and low voltages both divided by the typical output current?

Does that make any sense?

Thanks!

 

[poobah]

You need to divide a change (difference) in output voltage by a corresponding change in output current. They didn't give you the data to do this.

This is a logic device... probably not good for a linear application.

 

[ble0t]

It's not for a linear application persay. It's for buffering a digital output signal (more specifically SPDIF). I want to match an impedance for the primary side of a transformer. I can't get the output impedance of the transmitter I'm using, so I thought buffering it and using that output impedance would be the best idea.

 

[poobah]

HMMM... 25 Ohms might be a good guess for CMOS. I have calculated Zo for these device before.

Also look for "differential line (or bus) driver". They won't be lacking in spec's.

 

[ble0t]

Thanks much