Datasheet

KSZ8041TL/FTL/MLL
DS00002436B-page 56  2017 Microchip Technology Inc.
8.0 SELECTION OF ISOLATION TRANSFORMERS
A 1:1 isolation transformer is required at the line interface. An isolation transformer with integrated common-mode choke
is recommended for exceeding FCC requirements.
Table 8-1 lists recommended transformer characteristics.
TABLE 8-1: TRANSFORMER SELECTION CRITERIA
Parameter Value Test Conditions
Turns Ratio 1 CT:1 CT —
Open-Circuit Inductance (min.) 350 µH 100 mV, 100 kHz, 8 mA
Leakage Inductance (max.) 0.4 µH 1 MHz (min.)
Interwinding Capacitance (max.) 12 pF —
D.C. Resistance (max.) 0.9 —
Insertion Loss (max.) –1.0 dB 0 MHz to 65 MHz
HIPOT (min.) 1500 V
RMS
—
TABLE 8-2: QUALIFIED SINGLE-PORT MAGNETICS
Manufacturer Part Number Auto MDI-X
Bel Fuse S558-5999-U7 Yes
Bel Fuse (Mag Jack) SI-46001 Yes
Bel Fuse (Mag Jack) SI-50170 Yes
Delta LF8505 Yes
LanKom LF-H41S Yes
Pulse H1102 Yes
Pulse (low cost) H1260 Yes
Transpower HB726
TDK (Mag Jack) TLA-6T718
TABLE 8-3: TYPICAL REFERENCE CRYSTAL CHARACTERISTICS
Characteristic Value
Frequency 25 MHz
Frequency Tolerance (max.) ±50 ppm
Load Capacitance (max.) 20 pF
Series Resistance 40