
FEMTOCLOCKS CRYSTAL-TO-LVDS
CLOCK GENERATOR
ICS844021-01
IDT / ICS LVDS CLOCK GENERATOR
1
ICS844021BG-01 REV. A OCTOBER 23, 2012
GENERAL DESCRIPTION
The ICS844021-01 is an Ethernet Clock Generator. The
ICS844021-01 uses an 18pF parallel resonant crystal over the
range of 24.5MHz – 34MHz. For Ethernet applications, a 25MHz
crystal is used. The ICS844021-01 has excellent <1ps phase
jitter performance, over the 1.875MHz – 20MHz integration
range. The ICS844021-01 is packaged in a small 8-pin TSSOP,
making it ideal for use in systems with limited board space.
FEATURES
One Differential LVDS output
Crystal oscillator interface, 18pF parallel resonant crystal
(24.5MHz – 34MHz)
Output frequency range: 122.5MHz – 170MHz
VCO range: 490MHz – 680MHz
RMS phase jitter @ 125MHz, using a 25MHz crystal
(1.875MHz – 20MHz): 0.32ps (typical) @ 3.3V
3.3V or 2.5V operating supply
0°C to 70°C ambient operating temperature
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
ICS844021-01
8-Lead TSSOP
4.40mm x 3.0mm x 0.925mm
package body
G Package
Top View
VDDA
GND
XTAL_OUT
XTAL_IN
1
2
3
4
VDD
Q
nQ
OE
8
7
6
5
BLOCK DIAGRAM
OSC
Phase
Detector
VCO
490MHz - 680MHz
M = ÷20 (fixed)
N = ÷4 (fixed)
XTAL_IN
XTAL_OUT
OE
Q
nQ
Pullup
COMMON CONFIGURATION TABLE - Gb ETHERNET
PIN ASSIGNMENT
s
t
u
p
n
I
y
c
n
e
u
q
e
r
F
t
u
p
t
u
O
)
z
H
M
(
)
z
H
M
(
y
c
n
e
u
q
e
r
F
l
a
t
s
y
r
CM
N
n
o
i
t
a
c
i
l
p
i
t
l
u
M
N
/
M
e
u
l
a
V
5
20
24
5
2
1
6
.
6
20
24
5
3
.
3
1
3
.
3
30
24
5
6
.
6
1