ICS844256 Datasheet, PDF (1/13 Pages) Integrated Circuit Systems – FEMTOCLOCKS™ CRYSTAL-TO-LVDS FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS844256
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER
GENERAL DESCRIPTION
The ICS844256 is a Crystal-to-LVDS Clock
ICS
Synthesizer/Fanout Buffer designed for SONET
HiPerClockS™ _{and Gigabit Ethernet applications and is a}
member of the HiperClockS™ family of High
Performance Clock Solutions from ICS. The
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 ICS844256 make it an ideal clock for these
demanding applications.
FEATURES
• Six LVDS outputs
• Crystal oscillator interface
• Output frequency range: 62.5MHz to 622.08MHz
• Crystal input frequency range: 15.625MHz to 25.5MHz
• 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
• 0°C to 70°C ambient operating temperature
• Industrial temperature information available upon request
SELECT FUNCTION TABLE
• Available in both standard and lead-free RoHS-compliant
packages
Inputs
Function
FB_SEL N_SEL1 N_SEL0 M Divide N Divide M/N
0
0
0
25
1
25
0
0
1
25
2
12.5
0
1
0
25
4
6.25
0
1
1
25
5
5
1
0
0
32
1
32
1
0
1
32
2
16
1
1
0
32
4
8
1
1
1
32
8
4
BLOCK DIAGRAM
PIN ASSIGNMENT
PLL_BYPASS ^Pullup
XTAL_IN
XTAL_OUT
OSC
1
Output
PLL
Divider
0
Q0
VDDO 1
VDDO 2
nQ0
nQ2 3
Q2 4
nQ1 5
Q1
Q1 6
nQ1
nQ0 7
Q0 8
PLL_BYPASS 9
Q2
VDDA 10
nQ2
VDD 11
FB_SEL 12
24 Q3
23 nQ3
22 Q4
21 nQ4
20 Q5
19 nQ5
18 N_SEL1
17 GND
16 GND
15 N_SEL0
14 XTAL_OUT
13 XTAL_IN
FB_SEL ^Pulldown
N_SEL1 ^Pullup
Pullup
N_SEL0
Feedback
Divider
Q3
ICS844256
24-Lead, 300-MIL SOIC
nQ3
7.5mm x 15.33mm x 2.3mm
body package
Q4
M Package
Top View
nQ4
24-Lead TSSOP
4.40mm x 7.8mm x 0.92mm
Q5
body package
nQ5
G Package
Top View
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.
844256AM
www.icst.com/products/hiperclocks.html
REV. A NOVEMBER 29, 2005
1