Datasheet

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DP83865
5.0 Design Guide (Continued)
5.13.2 Magnetics
It is important to select the compoment that meets the
requirements. Per IEEE 802.3ab Clause 40.8, the compo-
nent requirements are listed in Table 57. In addition, the
transformer winding should have the configuration shown
in Figure 21. The recommended magnetics has an isola-
tion transformer followed by a common mode choke to
reduce EMI. There is an additional auto-transformer which
is center tapped. To save board space and reduce compo-
nent count, RJ-45 with integrated magnetics may be used.
The following are magnetics meeting the requirements
(Table 57).
Figure 21. Transformer configuration (1 ch)
TCT
TD+
TD-
MCT
MX+
MX-
Table 57. Magnetics Requirements
Parameter Min Typ Max Units Condition
Turn Ratio - 1:1 - - ± 1%
Insertion Loss - - -1.1 dB 0.1 - 1 MHz
- - -0.5 dB 1 - 60 MHz
- - -1.0 dB 60 - 100 MHz
- - -1.2 dB 100 - 125 MHz
Return Loss -18 - - dB 1 - 30 MHz
-14.4 - - dB 30 - 40 MHz
-13.1 - - dB 40 - 50 MHz
-12 - - dB 50 - 80 MHz
-10 - - dB 80 - 100 MHz
Differential to Common
Rejection Ration
-43 - - dB 1 - 30 MHz
-37 - - dB 30 - 60 MHz
-33 - - dB 60 - 100 MHz
Crosstalk -45 - - dB 1 - 30 MHz
-40 - - dB 30 - 60 MHz
-35 - - dB 60 - 100 MHz
Isolation 1,500 - - Vrms HPOT
Rise Time - 1.6 1.8 ns 10 - 90 %
Primary Inductance 350 - - uH -
Table 58. Recommended Magnetics
Manufacturer Description Part Number
Bel Fuse, Inc.
www.belfuse.com
10/100/1000 Mbps Isolation Transformer S558-5999-P3
10/100/1000 Mbps Isolation Transformer S558-5999-T3
10/100/1000 Mbps2X1 Integrated Magnetics 0843-2B1T-33
Delta
www.delta.tw
10/100/1000 Mbps Isolation Transformer LF9203
Halo
www.haloelectronics.com
10/100/1000 Mbps Isolation Transformer TG1G-S002NZ
Midcom
www.haloelectronics.com
10/100/1000 Mbps Isolation Transformer 000-7093-37R
Pulse Engineering, Inc.
www.pulseeng.com
10/100/1000 Mbps Isolation Transformer H5007
10/100/1000 Mbps Isolation Transformer H5008
Note: Contact Magnetics manufactures for latest part numbers and product specifications. All Magnetics should be thor-
oughly tested and validated before using them in production.