FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER
ICS844256I
GENERAL DESCRIPTION
FEATURES
The ICS844256I is a Crystal-to-LVDS Clock
• Six LVDS outputs
ICS
HiPerClockS™
Synthesizer/Fanout Buffer designed for SONET
and Gigabit Ethernet applications and is a
member of the HiperClockS™ family of High
Performance Clock Solutions from IDT. The
• Crystal oscillator interface
• Output frequency range: 62.5MHz to 625MHz
• Crystal input frequency range: 15.625MHz to 25.5MHz
output frequency can be set using the frequency select
pins and a 25MHz crystal for Ethernet frequencies, or a
19.44MHz crystal for SONET. The low phase noise character-
istics of the ICS844256I make it an ideal clock for these
demanding applications.
• RMS phase jitter at 125MHz, using a 25MHz crystal
(1.875MHz to 20MHz): 0.48ps (typical)
• Full 3.3V or 3.3V core, 2.5V output supply mode
• -40°C to 85°C ambient operating temperature
• Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
SELECT FUNCTION TABLE
Inputs
Function
FB_SEL N_SEL1 N_SEL0 M Divide N Divide
M/N
25
12.5
6.25
5
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
25
25
25
25
32
32
32
32
1
2
4
5
1
2
4
8
32
16
8
4
BLOCK DIAGRAM
PIN ASSIGNMENT
Q0
V
V
DDO
Q3
1
2
24
23
DDO
nQ3
Q4
nQ0
nQ2
Q2
3
4
22
21
Pullup
PLL_BYPASS
nQ4
Q1
nQ1
Q1
nQ0
Q0
5
6
7
20 Q5
19
18 N_SEL1
nQ5
1
0
nQ1
Output
Divider
GND
8
17
XTAL_IN
9
16
15
14
13
PLL_BYPASS
GND
Q2
OSC
PLL
VDDA
N_SEL0
XTAL_OUT
XTAL_IN
10
11
12
XTAL_OUT
nQ2
V
DD
FB_SEL
Q3
ICS844256I
24-Lead TSSOP, E-Pad
4.40mm x 7.8mm x 0.90mm
body package
Feedback
Divider
nQ3
Pulldown
FB_SEL
Q4
G Package
Top View
Pullup
nQ4
N_SEL1
Pullup
N_SEL0
Q5
nQ5
IDT™ / ICS™ LVDS FREQUENCY SYNTHESIZER W/FANOUT BUFFER
1
ICS844256BGI REV. A DECEMBER 21, 2007