KSZ8864RMNI MICREL [Micrel Semiconductor], KSZ8864RMNI Datasheet - Page 111

• Manufacturer Part Number: KSZ8864RMNI
• Description: Integrated 4-Port 10/100 Managed Switch with Two MACs MII or RMII Interfaces
• Manufacturer: MICREL [Micrel Semiconductor]

September 2011
Selection of Isolation Transformer
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 at line side. Request to separate the center taps of
RX/TX at chip side. Table 30 gives recommended transformer characteristics.
Notes:
1. The IEEE 802.3u standard for 100BASE-TX assumes a transformer loss of 0.5dB. For the transmit line transformer, insertion loss of up to 1.3dB
2. The center taps of RX and TX should be isolated for the low power consumption.
The following transformer vendors provide compatible magnetic parts for Micrel’s device:
Selection of Reference Crystal
Characteristics Name
Turns Ratio
Open-Circuit Inductance (minimum)
Leakage Inductance (maximum)
Inter-Winding Capacitance (maximum)
D.C. Resistance (maximum)
Insertion Loss (maximum)
HIPOT (minimum)
TDK
LanKom
Transpower
Delta
can be compensated by increasing the line drive current by means of reducing the ISET resistor value.
Vendor
Single Port Integrated
Chacteristics
Frequency
Frequency tolerance (maximum)
Load capacitance (maximum)
Series resistance (max ESR)
TLA-6T718A
LF-H41S
HB726
LF8505
Part
Table 32. Typical Reference Crystal Characteristics
MDIX
Auto
Yes
Yes
Yes
Yes
Table 30. Transformer Selection Criteria
Table 31. Qualified Magnetic Vendors
(1)
Number
of Ports
1 CT : 1 CT
1500Vrms
350µH
Value
0.4µH
1.0dB
12pF
1
1
1
1
0.9Ω
Pulse
Bel Fuse
YCL
Datatronic
111
25.00000
 = 50
Value
27
40
Vendor
Single Port
H1102
S558-5999-U7
PT163020
NT79075
Part
100mV, 100kHz, 8mA
Units
MHz
ppm
0MHz to 65MHz
Test Condition
pF

1MHz (min.)
MDIX
Auto
Yes
Yes
Yes
Yes
M9999-092011-1.4
Number of
Ports
1
1
1
1