KSZ8895MQ_12 MICREL [Micrel Semiconductor], KSZ8895MQ_12 Datasheet - Page 114

• Manufacturer Part Number: KSZ8895MQ_12
• Description: Integrated 5-Port 10/100 Managed Ethernet Switch with MII/RMII interface
• Manufacturer: MICREL [Micrel Semiconductor]

Micrel, Inc.
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. The following table gives recommended transformer characteristics.
Note:
The following transformer vendors provide compatible magnetic parts for Micrel’s device:
Selection of Reference Crystal
March 2012
Characteristics Name
Turns Ratio
Open-Circuit Inductance (min.)
Leakage Inductance (max.)
Inter-Winding Capacitance (max.)
D.C. Resistance (max.)
Insertion Loss (max.)
HIPOT (min.)
Pulse
YCL
TDK
LanKom
Datatronic
1.
2.
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 can be compensated by increasing the line drive current by means of reducing the ISET resistor value.
The center taps of RX and TX should be isolated for the low power consumption.
Vendors and Parts
Chacteristics
Frequency
Frequency tolerance (max)
Load capacitance (max)
Series resistance (max ESR)
H1664NL
PH406082
TLA-6T718A
LF-H41S
NT79075
Table 35. Typical Reference Crystal Characteristics
MDIX
Auto
Value
1 CT : 1 CT
350µH
0.4µH
12pF
0.9Ω
1.0dB
1500Vrms
Yes
Yes
Yes
Yes
Yes
Table 33. Transformer Selection Criteria
Table 34. Qualified Magnetic Vendors
(1)
Number
of Ports
4
4
1
1
1
Value
25.00000
<= 50
27
40
Pulse
Bel Fuse
YCL
Transpower
Delta
114
Vendors and Parts
Test Condition
100mV, 100kHz, 8mA
1MHz (min.)
0MHz to 65MHz
Units
MHz
ppm
pF

H1102
S558-5999-U7
PT163020
HB726
LF8505
KSZ8895MQ/RQ/FMQ
MDIX
Auto
Yes
Yes
Yes
Yes
Yes
M9999-032612-1.5
Number of
Ports
1
1
1
1
1