
FEMTOCLOCK CRYSTAL-TO-
3.3V, 2.5V LVPECL CLOCK GENERATOR
ICS843251I-15
IDT / ICS 3.3V, 2.5V LVPECL CLOCK GENERATOR
1
ICS843S51BGI-15 REV. A NOVEMBER 2, 2012
General Description
The ICS843251I-15 is an Ethernet Clock Generator. The
ICS843251I-15 uses an 18pF parallel resonant crystal over the
range of 23.2MHz - 30MHz. For Ethernet applications, a 25MHz
crystal is used. The ICS843251I-15 uses IDT’s 3rd generation low
phase noise VCO technology, and can achieve <1ps rms phase
jitter performance over the 1.875MHz – 20MHz integration range.
The ICS843251I-15 is packaged in a small 8-pin TSSOP, making it
ideal for use in systems with limited board space.
Features
One differential 3.3V LVPECL output pair
Crystal oscillator interface, 18pF parallel resonant crystal
(23.2MHz – 30MHz)
Output frequency range: 116MHz – 150MHz and
580MHz – 750MHz
VCO range: 580MHz – 750MHz
RMS phase jitter @ 125MHz, using a 25MHz crystal
(1.875MHz – 20MHz): 0.45ps (typical), 3.3V
Full 3.3V or 2.5V supply modes
-40°C to 85°C ambient operating temperature
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
Common Configuration Table
Inputs
Output Frequency (MHz)
Crystal Frequency (MHz)
FREQ_SEL
M
N
Multiplication Value
M/N
25
1
25
1
25
625
26.667
1
25
1
25
666.67
25
0
25
5
125
26.667
0
25
5
133.33
Pin Assignment
1
2
3
4
8
7
6
5
Q
nQ
FREQ_SEL
VCC
VCCA
VEE
XTAL_OUT
XTAL_IN
Block Diagram
OSC
Phase
Detector
VCO
580MHz - 750MHz
M = ÷25 (fixed)
FREQ_SEL
N
1
÷1
0 (default) ÷5
Q
nQ
FREQ_SEL
XTAL_IN
XTAL_OUT
Pulldown
ICS843251I-15
8 Lead TSSOP
4.40mm x 3.0mm x 0.925mm
package body
G Package
Top View