1893BFILFT IDT, 1893BFILFT Datasheet - Page 27

• Manufacturer Part Number: 1893BFILFT
• Description: Ethernet ICs 3.3V 10/100 BASE TX INTEGRATED PHYCEIVER
• Manufacturer: IDT

Specifications of 1893BFILFT

• Rohs: yes
• Part # Aliases: ICS1893BFILFT

ICS1893BF, Rev. F, 5/13/10
5.4 Clock Reference Interface
Oscillator
The REF_IN pin provides the ICS1893BF Clock Reference Interface. The ICS1893BF 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
ICS1893BF 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 5.2.
Figure 5-2. Crystal or Oscillator Operation
Crystal
ICS1893BF Data Sheet Rev. F - Release
25.000
33 pF
CMOS
MHz
REF_OUT
REF_OUT
46
NC
46
ICS1893BF
25.000MHz
ICS1893BF
33 Ohm
Copyright © 2009, IDT, Inc.
REF_IN
REF_IN
All rights reserved.
47
47
27
33 pF
10 pF
Chapter 5 Interface Overviews
May, 2010