Micrel, Inc.
KSZ8041NL/RNL
Selection of Isolation Transformer
A 1:1 isolation transformer is required at the line interface. An isolation transformer with integrated common-mode chokes
is recommended for exceeding FCC requirements.
The Table 17 gives recommended transformer characteristics.
Parameter
Value
Test Condition
Turns ratio
1 CT : 1 CT
350μH
0.4μH
Open-circuit inductance (min.)
Leakage inductance (max.)
Inter-winding capacitance (typ.)
D.C. resistance (typ.)
Insertion loss (max.)
HIPOT (min.)
100mV, 100kHz, 8mA
1MHz (min.)
12pF
0.9Ω
-1.0dB
1500Vrms
0MHz – 65MHz
Table 17. Transformer Selection Criteria
Magnetic Manufacturer
Bel Fuse
Part Number
S558-5999-U7
SI-46001
SI-50170
LF8505
Auto MDI-X
Yes
Number of Port
1
1
1
1
1
1
1
1
1
Bel Fuse (Mag Jack)
Bel Fuse (Mag Jack)
Delta
Yes
Yes
Yes
LanKom
LF-H41S
H1102
Yes
Pulse
Yes
Pulse (low cost)
Transpower
H1260
Yes
HB726
Yes
TDK (Mag Jack)
TLA-6T718
Yes
Table 18. Qualified Single Port Magnetics
Selection of Reference Crystal
Characteristics
Value
Units
MHz
ppm
pF
Frequency
25
Frequency tolerance (max)
Load capacitance
±50
20
Series resistance
40
Ω
Table 19. Typical Reference Crystal Characteristics
September 2010
53
M9999-090910-1.4
MICREL [ MICREL SEMICONDUCTOR ]
