Download Micrel KSZ8895 Specifications

Micrel, Inc.
KSZ8895MQ/RQ/FMQ
Selection of Isolation Transformer(1)
One simple 1:1 isolation transformer is needed at the line interface. An isolation transformer with integrated commonmode 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.
Characteristics Name
Value
Turns Ratio
Test Condition
1 CT : 1 CT
Open-Circuit Inductance (min.)
350µH
100mV, 100kHz, 8mA
Insertion Loss (max.)
1.1dB
0.1MHz to 100MHz
HIPOT (min.)
1500Vrms
Table 33. Transformer Selection Criteria
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
can be compensated by increasing the line drive current by means of reducing the ISET resistor value.
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:
Vendors and Parts
Auto
MDIX
Number
of Ports
Vendors and Parts
Auto
MDIX
Number of
Ports
Pulse
H1664NL
Yes
4
Pulse
H1102
Yes
1
YCL
PH406082
Yes
4
Bel Fuse
S558-5999-U7
Yes
1
TDK
TLA-6T718A
Yes
1
YCL
PT163020
Yes
1
LanKom
LF-H41S
Yes
1
Transpower
HB726
Yes
1
Datatronic
NT79075
Yes
1
Delta
LF8505
Yes
1
Table 34. Qualified Magnetic Vendors
Selection of Reference Crystal
Chacteristics
Value
Units
25.00000
MHz
<= ±50
ppm
Load capacitance (max)
27
pF
Series resistance (max ESR)
40
Ω
Frequency
Frequency tolerance (max)
Table 35. Typical Reference Crystal Characteristics
March 12, 2014
117
Revision 1.7