ISO7640FM for ethernet Isolation useable?

Johannes Segschneider

Other Parts Discussed in Thread: ISO7640FM

I need to isolate an ethernet RJ45 LAN connection. Therefore i wanted to use optical couplers, cause i need a garantee, that i can't sent anything on the ethernet-port.

So my Question is, if i can use the ISO7640FM for this. With it's 150MBAUD it is the fastest coupler i found, but i am not sure, if it works with an low ethernet-signal.

over 13 years ago

0 Thomas Kugelstadt over 13 years ago

TI__Mastermind 28265 points

What do you mean with low Ethernet signal?

Low signal strength, small amplitude?

The logic threshold levels of the isolator are specified in the data sheet. If the Ethernet signal is higher than these levels, it should work, if they are not, it won't work.

- Thomas

0 Thomas Kugelstadt over 13 years ago in reply to Thomas Kugelstadt

TI__Mastermind 28265 points

One more clarification.

The isolators, whether optical or capacitive, are single-ended logic devices and will need to be installed on the control side of the Ethernet Phy, and not on the bus side, which is differential.

- Thomas

0 Johannes Segschneider over 13 years ago in reply to Thomas Kugelstadt

Prodigy 20 points

Thanks for you answer.

Okay i see, so i need definitly an controller... i only wanted to isolate the bus and give the whole bus signal to a Computer. This is only needed to make sure i can't send anything, but if it only works with an controller, its quite useless i think!

0 Scott Monroe over 13 years ago in reply to Johannes Segschneider

TI__Mastermind 20590 points

Ethernet by 802.3 standard is already functionally / basic isoltated. If you are using a standard Ethernet transformer per 802.3 it is normally isolated to about 1kv or 1.5kV. You can buy other transformers that are more or switch to Fiber (FX) option with on of the DP8xxxx or up coming TLK1xx PHYs supporting Fiber. These are the normal ways to isolate Fast (100mbsp) ethernet.

-- Scott

Interface

Interface forum

ISO7640FM for ethernet Isolation useable?