FEMTOCLOCK™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
ICS844251-14
General Description
Features
The ICS844251-14 is an Ethernet Clock Generator
• One differential LVDS output pair
and a member of the HiPerClocksTM family of high
performance devices from IDT. The ICS844251-14
uses an 18pF parallel resonant crystal over the
range of 23.2MHz – 30MHz. For Ethernet
S
IC
• Crystal oscillator interface designed for 18pF, parallel resonant
HiPerClockS™
crystal (23.2MHz – 30MHz)
• Output frequency ranges: 145MHz – 187.5MHz and
580MHz – 750MHz
applications, a 25MHz crystal is used. The device has excellent
<1ps phase jitter performance, over the 1.875MHz – 20MHz
integration range. The ICS844251-14 is packaged in a small 8-pin
TSSOP, making it ideal for use in systems with limited board
space.
• VCO range: 580MHz – 750MHz
• RMS phase jitter at 156.25MHz, using a 25MHz crystal
(1.875MHz – 20MHz): 0.53ps (typical)
• Full 3.3V or 2.5V output supply modes
• 0°C to 70°C ambient operating temperature
• Available in lead-free (RoHS 6) package
Common Configuration Table
Inputs
Output Frequency Range
Crystal Frequency (MHz)
FREQ_SEL
M
25
25
25
N
1
1
4
Multiplication Value M/N
(MHz)
25
1
1
0
25
25
625
26.67
666.67
156.25
25 (default)
6.25
Pin Assignment
Block Diagram
Pulldown
FREQ_SEL
1
2
3
4
8
7
6
5
VDDA
GND
VDD
Q
nQ
XTAL_OUT
XTAL_IN
FREQ_SEL
0 (default)
1
N
÷4
÷1
XTAL_IN
OSC
XTAL_OUT
FREQ_SEL
Q
nQ
VCO
Phase
Detector
580MHz - 750MHz
ICS844251-14
8 Lead TSSOP
4.40mm x 3.0mm x 0.925mm
package body
M = ÷25 (fixed)
G Package
Top View
IDT™ / ICS™ LVDS CLOCK GENERATOR
1
ICS844251BG-14 REV. A MAY 1, 2009