IDT1893CFLFT IDT, Integrated Device Technology Inc, IDT1893CFLFT Datasheet - Page 21

• Manufacturer Part Number: IDT1893CFLFT
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT1893CFLFT

• Lead Free Status / RoHS Status: Compliant

ICS1893CF, Rev. J, 08/11/09
If a crystal is used as the clocking source, connect it to both the Ref_in (pin 47) and Ref_out (pin 46) pins
of the ICS1893CF. A pair of bypass capacitors on either side of the crystal are connected to ground. The
crystal is used in the parallel resonance or anti-resonance mode. The value of the load caps serve to adjust
the final frequency of the crystal oscillation. Typical applications would use 33pF load caps. The exact
value will be affected by the board routing capacitance on Ref_in and Ref_out pins. Smaller load capacitors
raise the frequency of oscillation. Once the exact value of load capacitance is established it will be the
same for all boards using the same specification crystal. The best way to measure the crystal frequency is
to measure the frequency of TXCLK (pin 37) using a frequency counter with a 1 second gate time. Using
the buffered output TXCLK prevents the crystal frequency from being affected by the measurement. The
crystal specification is shown in Table 5.1.
Table 5-1. 25MHz Crystal Specification
Table 5-2. 25MHz Oscillator Specification
Specifications
Fundamental Frequency
(tolerance is sum of freq.,
temp., stability and aging.)
Freq. Tolerance
Input Capacitance
Specifications
Output Frequency
Freq. Stability (including aging)
Duty cycle CMOS level
one-half VDD
VIH
VIL
Period Jitter
Input Capacitance
ICS1893CF Data Sheet Rev. J - Release
Copyright © 2009, Integrated Device Technology, Inc.
Symbol Minimum
F0
∆
Cin
Symbol Minimum
F0
∆
Tw/T
Tjitter
CIN
F/f
F/f
24.99875 25.00000
24.99875 25.00000
All rights reserved.
21
2.79
35
Typical Maximum
Typical Maximum
3
3
25.00125
25.00125
±
±
0.33
500
50
50
65
Chapter 5 Interface Overviews
Volts
Volts
MHz
MHz
Unit
ppm
Unit
ppm
pS
pF
pF
%
August, 2009