ICS1893CF Data Sheet - Release
Chapter 9 DC and AC Operating Conditions
9.3 Recommended Component Values *
Table 9-3. Recommended Component Values for ICS1893CF
Parameter
Minimum
Typical
Maximum
Tolerance
Units
MHz
Ω
Oscillator Frequency
10TCSR Resistor Value
100TCSR Resistor Value
LED Resistor Value
–
–
25
2.43k
–
–
± 50 ppm †
1%
1%
–
–
See Figure 9-1
1k
–
Ω
510
10k
Ω
† There are two IEEE Std. 802.3 requirements that define the tolerance for the frequency of the oscillator.
• 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).
Figure 9-1. ICS1893CF 10TCSR and 100TCSR
Typical Board Layouts
10TCSR and 100TCSR Bias Resistors
ICS1893CF
VDD
18
10TCSR
19
100TCSR
20
18.2KΩ 1%
VDD
10TCSR
100TCSR
1.82KΩ 1%
2.43KΩ 1%
Note:
1. The bias resistor networks set the 10baseT and 100baseTX output amplitude levels.
2. Amplitude is directly related to current sourced out of the 10TCSR and 100TCSR pins.
3. Resistor values shown above are typical. User should check amplitudes and adjust for transformer effects
4. The VDD connection to the 18.2K resistor can connect to any VDD. The 18.2K resistor provides negative
feedback to compensate for VDD changes. Lowering the 18.2K value will lower the 100baseT amplitude.
* For backward compatibillity, refer to the “1893C Alternate Schematic” application note.
ICS1893CF, Rev. J, 08/11/09
August, 2009
Copyright © 2009, Integrated Device Technology, Inc.
All rights reserved.
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