I347-AT4 Datasheet, PDF (34/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

I347-AT4—Device Functionality
The external loopback test setup requires the presence of a MAC that will originate the
frames to be sent out through the PHY. Instead of a normal RJ-45 cable, the loopback
stubs allows the PHY to self-link at 1000 Mb/s. It also allows the actual external
loopback. See Figure 11. The MAC should see the same packets it sent, looped back to
it.
MAC
I347-ATA
Loopback Stub
1
2
3
Mag/RJ-45
4
5
6
7
8
Figure 11. Test Setup for 10/100/1000 Mb/s Modes using an External Loopback Stub
3.4
Synchronizing FIFO
5.0 GHz
SERDES
8/10
8/10
K28.5 to
K28.1
Swapper
Mux
27_4.0
Port 0
Port 1
Port 2
Port 3
Mux
27_4.14
K28.1 to
K28.5
27_4.1 _Swapper
Port 0
De-Mux
Port 1
Port 2
Port 3
The I347-AT4 has a transmit and receive synchronizing FIFO to reconcile frequency
differences between the clocks of the MAC interface and the media side. The FIFO
depths can be increased in length to support longer frames. The I347-AT4 can handle
jumbo frame sizes up to 16 KB with up to ± 100 PPM clock jitter. The deeper the FIFO
depth, the higher the latency is.
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