PRELIMINARY
ICS843256I
Integrated
Circuit
Systems, Inc.
FEMTOCLOCKS™ CRYSTAL-TO-3.3V LVPECL
FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER
GENERAL DESCRIPTION
FEATURES
The ICS843256I is a Crystal-to-3.3V LVPECL • Six LVPECL outputs
ICS
HiPerClockS™
Clock Synthesizer/Fanout Buffer designed for
• Crystal oscillator interface
Fibre Channel and Gigabit Ethernet applications
and is a member of the HiperClockS™ family of
High Performance Clock Solutions from ICS.The
• Output frequency range: 53.125MHz to 333.3333MHz
• Crystal input frequency range: 25MHz to 33.333MHz
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 charac-
teristics of the ICS843256I make it an ideal clock for these
demanding applications.
• RMS phase jitter at 125MHz, using a 25MHz crystal
(1.875MHz to 20MHz): 0.33ps (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 and lead-free RoHS-compliant
packages
SELECT FUNCTION TABLE
Inputs
Function
FB_SEL N_SEL1 N_SEL0 M Divide N Divide
M/N
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
25
12.5
6.25
5
32
16
8
4
BLOCK DIAGRAM
PIN ASSIGNMENT
VCCO
VCCO
1
24
23
22
Q3
Q0
2
nQ3
3
nQ2
Q4
nQ0
4
Q2
nQ1
Q1
nQ0
nQ4
Q5
nQ5
N_SEL1
VEE
21
20
19
18
17
16
15
14
13
Pullup
PLL_BYPASS
5
6
7
Q1
1
0
nQ1
Q0
8
9
10
11
12
Output
Divider
PLL_BYPASS
VCCA
VEE
XTAL_IN
OSC
PLL
Q2
N_SEL0
XTAL_OUT
XTAL_IN
VCC
FB_SEL
XTAL_OUT
nQ2
ICS843256I
24-Lead, 300-MIL SOIC
7.5mm x 15.33mm x 2.3mm
body package
Q3
Feedback
Divider
nQ3
M Package
Top View
Pulldown
Pullup
Q4
FB_SEL
N_SEL1
nQ4
24-Lead TSSOP
4.40mm x 7.8mm x 0.92mm
body package
Pullup
N_SEL0
Q5
G Package
Top View
nQ5
The Preliminary Information presented herein represents a product in prototyping or pre-production. The noted characteristics are based on
initial product characterization. Integrated Circuit Systems, Incorporated (ICS) reserves the right to change any circuitry or specifications
without notice.
843256AMI
www.icst.com/products/hiperclocks.html
REV.A JUNE 16, 2006
1