Specs for Line Driver

[qdn]

Hello,

I'm not very clear on what are the specs to look for when trying to see if a line driver IC is capable of driving a certain line. For example, take the SN74ls240 https://ecee.colorado.edu/~mcclurel/sn74ls240rev5.pdf , if I am to take that to drive a coax cable about 150 feet with 50 ohm load for impedance match, what parameters do I need to look at to determine if this IC is capable of driving the cable? Thanks!

 

[Mikebits]

You can usually go by the IOH and IOL spec. For 50 ohm you need about 40 ma to meet VIH logic levels. The part you listed is not a 50 ohm line driver. See this data sheet. https://www.electro-tech-online.com/custompdfs/2010/05/sn74128.pdf Or this part.
https://www.electro-tech-online.com/custompdfs/2010/05/sdls210.pdf

This is older tech, I am sure there are newer logic families, but I am done looking.

 

[qdn]

Thanks for replying. One more question, what is the significant of putting a resistor after the driver, assume its for impedance matching to Zo of transmission line and Zload. Though, I saw working design that did not put a resistor after the driver at all.