IDT1893AFLFT IDT, Integrated Device Technology Inc, IDT1893AFLFT Datasheet - Page 29

• Manufacturer Part Number: IDT1893AFLFT
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT1893AFLFT

• Lead Free Status / RoHS Status: Compliant

6.4 Clock Reference Interface
ICS1893AF, Rev. D 10/26/04
Oscillator
The REF_IN pin provides the ICS1893AF Clock Reference Interface. The ICS1893AF 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
ICS1893AF 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 6.1.
Figure 6-3. Crystal or Oscillator Operation
Crystal
ICS1893AF Data Sheet - Release
33 pF
CMOS
25.000
MHz
REF_OUT
REF_OUT
46
NC
46
25.000MHz
33 Ohm
Copyright © 2004, Integrated Circuit Systems, Inc.
REF_IN
REF_IN
All rights reserved.
47
47
29
33 pF
10 pF
Chapter 6 Interface Overviews
October, 2004