CS8900A
Crystal LAN™ ISA Ethernet Controller
7.5 10BASE-T WIRING
CS8900A
1 :
2
TD +
1
Rt
TXD +
68 pF
0.01
TXD -
Rt
TD -
2
µ
F
RJ45
1 : 1
RD +
3
RXD+
+
Rr
Rr
0.01 F
µ
RXD-
-
RD -
6
•
If a center tap transformer is used on the RXD+ and RXD- inputs, replace the pair of Rr resistors with
a single 2xRr resistor.
•
•
The Rt and Rr resistors are ±1% tolerance.
The CS8900A supports 100, 120, and 150 Ω unshielded twisted pair cables. The proper values of Rt
and Rr, for a given cable impedence, are shown below:
Cable Impedance (Ω)
Rt (Ω)
24.3
Rr (Ω)
49.9
60.4
75
100
120
150
30.1
37.4
•
Note: for 3.3V operation the turns ratio on TXD+ and TXD- is 1:2.5, rt is 8Ω for 100Ω cable and the
68pF cap changes to 560pF.
CIRRUS LOGIC PRODUCT DATA SHEET
120
DS271PP3
CIRRUS [ CIRRUS LOGIC ]
