ICS1893Y-10 Datasheet, PDF (34/150 Pages) –

ICS1893Y-10 Data Sheet - Release
Chapter 5 Interface Overviews
5.6 Clock Reference Interface
The REF_IN pin provides the ICS1893Y-10 Clock Reference Interface. The ICS1893Y-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
ICS1893Y-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 5-3. Crystal or Oscillator Operation
Crystal
REF_OUT
52
REF_IN
53
25.000MHz
33 pF
33 pF
Oscillator
REF_OUT
52
REF_IN
53
NC
CMOS
25.000
MHz
33 Ohm
10 pF
ICS1893Y-10 Rev F 1/20/04
Copyright © 2004, Integrated Circuit Systems, Inc.
All rights reserved.
34
January, 2004