LXT972 Level One, LXT972 Datasheet - Page 32

• Manufacturer Part Number: LXT972
• Description: 3.3V Dual-Speed Fast Ethernet Transceiver Datasheet
• Manufacturer: Level One

LXT972 3.3V Dual-Speed Fast Ethernet Transceiver
Table 14: Magnetics Requirements
Table 15: RJ-45 Pin Comparison of NIC and
32
Rx turns ratio
Tx turns ratio
Insertion loss
Primary inductance
Transformer isolation
Differential to common mode rejection
Return Loss
Magnetics Information
Typical Twisted-Pair Interface
The LXT972 requires a 1:1 ratio for both the receive
and transmit transformers. The transformer isolation
voltage should be rated at 2 kV to protect the circuitry
from static voltages across the connectors and cables.
Refer to
Table 15
connections for NIC and switch applications in a
typical twisted-pair interface setting.
Symbol
TPON
TPOP
TPIN
TPIP
Table 14
Switch Twisted-Pair Interfaces
Parameter
provides a comparison of the RJ-45
for transformer requirements.
Switch
1
2
3
6
APPLICATION INFORMATION
RJ-45
NIC
Min
350
3
6
1
2
0.0
-16
-10
40
35
–
–
–
Nom
1 : 1
1 : 1
1.5
0.6
–
–
–
–
–
A cross-reference list of magnetic manufacturers and
part numbers is available in Application Note 073,
Magnetic Manufacturers, which can be found on the
Level One web site (www.level1.com). Before
committing to a specific component, designers should
contact the manufacturer for current product
specifications, and validate the magnetics for the
specific application.
Figure 20 on page 33
interface with the RJ-45 connections crossed over for
a switch configuration.
a typical twisted-pair interface with the RJ-45
connections configured for a NIC application.
Max
1.1
–
–
–
–
–
–
–
–
Units
dB
kV
dB
dB
dB
dB
–
–
H
.1 to 60 MHz
60 to 100 MHz
30 MHz
80 MHz
Figure 21 on page 34
shows a typical twisted-pair
Test Condition
provides