EPF8028G Datasheet, PDF (2/2 Pages) PCA ELECTRONICS INC. – 10/100 LAN Interface Module for NIC/HUB Card Applications, Mini Package

ELECTRONICS INC.
10/100 LAN Interface Module for
NIC/HUB Card Applications, Mini Package
EPF8028G
The circuit below is a guideline for interconnecting PCA’s EPF8028G with QSI6611 and QSI6612 chip set for 10/100 Mb/s
applications. Further details can be obtained from the chip manufacturer application notes.
Typical insertion loss of the isolation transformer is 0.5dB. This parameter covers the entire spectrum of the encoded
signals in 10/100 protocols. Under terminated conditions, to transmit a 2V pk-pk signal across the cable, you must adjust
the chips supporting resistor to get at least 2.12V pk-pk across the transmit pins.
It is recommended that system designers do not use the receiver side center tap to ground, via a capacitor. This may
worsen EMI, specifically if the secondary “common mode termination” is pulled to chassis ground as shown.
The phantom resistors shown around the connector have been known to suppress unwanted radiation that unused wires
pick up from the immediate environment. Their placement and use are to be considered carefully before a design is
finalized.
The “common mode termination” load of 75 Ω shown from the center taps of the secondary may be taken to chassis ground
via a cap of suitable value. This depends upon user’s design, EMI margin etc.
It is recommended that there be a neat separation of ground planes in the layout. It is generally accepted practice to limit
the plane off at least 0.05 inches away from the chip side pins of EPF8028G. There need not be any ground plane beyond
this point.
For best results, PCB designer should design the outgoing traces preferably to be 50 Ω, balanced and well coupled to
achieve minimum radiation from these traces.
TX+
TX-
QSI6611
or
QSI6612
RX+
RX-
Typical Application Circuit for UTP
+5V
16
14
11
1
9
3
2
75Ω
15
50Ω
25Ω
6
75Ω
50Ω
8
25Ω
10
High Voltage
EPF8028G
Capacitor
CM Capacitor
Chassis
Ground
1
Xmit
2
3
Rcv
6
4 ^RJ45*
5
7
8
Node
Pinout
Notes : * NIC Side is shown. Hub side connection will have crossover swapping pins 3-6 & 1-2.
PCA ELECTRONICS, INC.
16799 SCHOENBORN ST.
NORTH HILLS, CA 91343
CSF8028Gb Rev. 2 11/20/96
TEL: [phone]
FAX: [phone]
http://www.pca.com