ICS1892 Datasheet, PDF (121/148 Pages) Integrated Circuit Systems – 10Base-T/100Base-TX Integrated PHYceiver

ICS1892
Chapter 10 DC and AC Operating Conditions
10.3 Recommended Component Values
Table 10-3 lists the recommended component values for the ICS1892.
Table 10-3. Recommended Component Values
Parameter
Crystal Frequency
10TCSR Resistor Value
100TCSR Resistor Value
LED Resistor Value
Minimum Typical
–
25
–
2.0k
–
7.15k
510
1k
Maximum
–
–
–
10k
Tolerance
± 50 ppm †
1%
1%
–
Units
MHz
Ω
Ω
Ω
Note: Do not put bypass capacitors across the 10TCSR or 100TCSR resistors. The bypass capacitor will
cause the bandgap circuit to oscillate.
† There are two IEEE Std 802.3 requirements that drive the tolerance for the frequency of the crystal.
• Clause 22.2.2.1 requires the MII TX_CLK to have an accuracy of ± 100 ppm.
• Clause 24.2.3.4 is more stringent. It requires the code-bit timer to have an accuracy of 0.005% (that is, ±50 ppm).
ICS1892, Rev. D, 2/26/01
© 2000-2001, Integrated Circuit Systems, Inc.
All rights reserved.
121
February 26, 2001