MDI termination

The paired MDI signals from the PHY to the magnetics in a GbE application are each terminated by a 50R resistor and then together to a 10nF capacitor to GND. However some applications connect the 2 resistors to Vcc (2.5V) as well. Can anyone explain why some configurations are like this and others aren't? Is it something specific to the magnetics?



Reply to
Loading thread data ...

It is not the magnetics; more likely, some implementations need a "pullup" to the higher voltage to provide power to the output driver through the terminating resistors. This is a function of the configuration of the output transistors in the PHY chip.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

Reply to
Rich Seifert Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.