KS8995M
Micrel
Selection of Isolation Transformer
(1)
One simple 1:1 isolation transformer is needed at the line interface. An isolation transformer with integrated common-mode
choke is recommended for exceeding FCC requirements. The following table gives recommended transformer characteristics.
Characteristics Name
Turns Ratio
Open-Circuit Inductance (min.)
Leakage Inductance (max.)
Inter-Winding Capacitance (max.)
D.C. Resistance (max.)
Insertion Loss (max.)
HIPOT (min.)
Note:
1. The IEEE 802.3u standard for 100BaseTX assumes a transformer loss of 0.5dB. For the transmit line transformer, insertion loss of up to 1.3dB can
be compensated by increasing the line drive current by means of reducing the ISET resistor value.
Value
1 CT : 1 CT
350碌H
0.4碌H
12pF
0.9鈩?/div>
1.0dB
1500Vrms
Test Condition
100mV, 100 KHz, 8mA
1MHz (min.)
0MHz to 65MHz
The following transformer vendors provide compatible magnetic parts for Micrel鈥檚 device:
4-Port Integrated
Vendor
Part
Pulse
Bel Fuse
YCL
Transpower
Delta
LanKom
H1164
558-5999-Q9
PH406466
HB826-2
LF8731
SQ-H48W
Auto
MDIX
Yes
Yes
Yes
Yes
Yes
Yes
Number
of Ports
4
4
4
4
4
4
Single Port
Vendor
Pulse
Bel Fuse
YCL
Transpower
Delta
LanKom
Part
H1102
S558-5999-U7
PT163020
HB726
LF8505
LF-H41S
Auto
MDIX
Yes
Yes
Yes
Yes
Yes
Yes
Number
of Ports
1
1
1
1
1
1
Table 24. Qualified Magnetics Lists
M9999-120403
72
December 2003
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