Eurotech Appliances Eurotech Ethernet Adapter An0038 - Manual (Page 10)

10 Application Note
Important Note. Connection to a 100BASE-TX hub for 100 Mbps operation requires Cat. 5
Unshielded Twisted-Pair (UTP) cable or Cat. 5 Shielded Twisted-Pair (STP) cable. The maximum
length between the 100BASE-TX hub and the adapter is 100 meters. Connection to a 10BASE-T hub
for 10 Mbps operation requires a Cat. 3, 4, 5 UTP cable or Cat. 5 STP cable. Preferred maximum
cable length between CPU-1220 module and Ethernet adapter is 10 cm (4”)
Ethernet physical adapter Versions
This physical adapter is available in two different versions:
Table 4. Physical Adapter code
EurotechCODE Description
Valid for
RTL8139
ACS-9071-00 RJ45 ETHERNET ADAPTER FOR CPU-1220 AND CPU-1231 B
ACS-9071-03 RJ45 Ethernet adapter for CPU-1232 and CPU-1220 C
Warning: To prevent incorrect data transmissions select the proper physical adapter device
depending on the Realtek RTL8139 chipset installed on the CPU-1220.
Integration of the Ethernet physical adapter
If the Ethernet physical adapter has to be integrated over a custom circuitry, please refer to Eurotech for
detailed information about schematics.
Regarding schematics, a good choice is isolating the Ethernet adapter section from the rest of the power
supply section. Derive the supply directly from the J4 Ethernet Connector of the CPU-1220. In this way if
different versions of Realtek RTL8139 chipsets are installed no damage occurs when you connect J4 to the
carrier board.
Warning: please take care on the Realtek RTL8139 version used in order to avoid short-circuits
between +5V and +3.3V when deriving power supply.