ics1893cy-10 Integrated Device Technology, ics1893cy-10 Datasheet - Page 31

• Manufacturer Part Number: ics1893cy-10
• Description: 3.3-v 10base-t/100base-tx Integrated Phyceiver
• Manufacturer: Integrated Device Technology

5.6 Clock Reference Interface
ICS1893CY-10 Rev 1/07
Oscillator
The REF_IN pin provides the ICS1893CY-10 Clock Reference Interface. The ICS1893CY-10 requires a
single clock reference with a frequency of 25 MHz ±50 parts per million. This accuracy is necessary to meet
the interface requirements of the ISO/IEEE 8802-3 standard, specifically clauses 22.2.2.1 and 24.2.3.4.
The ICS1893CY-10 supports two clock source configurations: a CMOS oscillator or a CMOS driver. The
input to REF_IN is CMOS (10% to 90% VDD), not TTL. Alternately, a 25MHz crystal may be used. The
Oscillator specifications are shown in Table 5.4.
Figure 5-2. Crystal or Oscillator Operation
Crystal
ICS1893CY-10 - Release
33 pF
CMOS
25.000
MHz
REF_OUT
REF_OUT
52
NC
52
25.000MHz
33 Ohm
Copyright © 2007, Integrated Device Technology, Inc.
REF_IN
REF_IN
All rights reserved.
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53
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33 pF
10 pF
Chapter 5 Interface Overviews