
FEMTOCLOCK CRYSTAL-TO-LVDS
CLOCK GENERATOR
ICS844251-14
IDT / ICS LVDS CLOCK GENERATOR
1
ICS844251BG-14 REV. A NOVEMBER 19, 2012
General Description
The ICS844251-14 is an Ethernet Clock Generator. The
ICS844251-14 uses an 18pF parallel resonant crystal over the
range of 23.2MHz – 30MHz. For Ethernet 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.
Features
One differential LVDS output pair
Crystal oscillator interface designed for 18pF, parallel resonant
crystal (23.2MHz – 30MHz)
Output frequency ranges: 145MHz – 187.5MHz and
580MHz – 750MHz
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
(MHz)
Crystal Frequency (MHz)
FREQ_SEL
M
N
Multiplication Value M/N
25
1
25
1
25
625
26.67
1
25
1
25
666.67
25 (default)
0
25
4
6.25
156.25
1
2
3
4
8
7
6
5
VDDA
GND
XTAL_OUT
XTAL_IN
VDD
Q
nQ
FREQ_SEL
ICS844251-14
8 Lead TSSOP
4.40mm x 3.0mm x 0.925mm
package body
G Package
Top View
OSC
Phase
Detector
VCO
580MHz - 750MHz
M = ÷25 (fixed)
FREQ_SEL
N
0 (default)
÷4
1
÷1
Pulldown
XTAL_IN
XTAL_OUT
FREQ_SEL
Q
nQ
Block Diagram
Pin Assignment