CRYSTAL-TO-LVDS PCI EXPRESS™
CLOCK SYNTHESIZER W/SPREAD SPECTRUM
ICS844202-245
IDT
™
/ ICS
™
LVDS PCI EXPRESS™ CLOCK SYNTHESIZER 1 ICS844202BK-245 REV. A JULY 9, 2007
PRELIMINARY
GENERAL DESCRIPTION
The ICS844202-245 is a 2 output PCI Express™ clock
synthesizer optimized to generate low jitter PCIe
reference clocks with or without spread spectrum
modulation and is a member of the HiPerClockS™
family of high performance clock solutions from IDT.
Spread type and amount can be configured via the SSC control
pins. Using a 25MHz, 18pF parallel resonant crystal, the device
will generate LVDS clocks at either 25MHz, 100MHz, 125MHz or
250MHz. The ICS844202-245 uses a low jitter VCO that easily
meets PCI Express jitter requirements and is packaged in a
32-pin VFQFN package.
FEATURES
• Two LVDS outputs at 25MHz, 100MHz, 125MHz or 250MHz
• Crystal oscillator interface, 25MHz, 18pF parallel resonant
crystal
• Supports the following output frequencies:
25MHz, 100MHz, 125MHz or 250MHz
• VCO range: 240MHz - 700MHz
• Supports SSC downspread at 0.50% and -0.75%,
centerspread at ±0.25% and no spread options
• Cycle-to-cycle jitter: 70ps (typical)
• Period jitter: 40ps (typical)
• Full 3.3V power supply mode
• 0°C to 70°C ambient operating temperature
• Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
HiPerClockS™
ICS
BLOCK DIAGRAM
32 31 30 29 28 27 26 25
9 10 11 12 13 14 15 16
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
V
DD
VDD
nc
nc
V
DDO
nc
FSEL0
nc
GND
OE
XTAL_OUT
XTAL_IN
OEB
V
DD
SSC0
FSEL1
nQ1
Q1
V
DDO
VDDA
GND
GND
nQ0
Q0
nc
nc
GND
nc
nc
SSC1
nc
GND
ICS844202-245
32-Lead VFQFN
5mm x 5mm x 0.75mm
package body
K Package
Top View
Phase
Detector
VCO
240-700MHz
Feedback Divider
÷20
Spread Spectrum
Control
OSC
0 0 PLL Bypass
0 1 ÷5
1 0 ÷4
1 1 ÷2
Q0
nQ0
Q1
nQ1
OE
XTAL_IN
XTAL_OUT
SSC[1:0]
FSEL[1:0]
Pullup
Default = 100MHz
25MHz
Pullup:Pullup
Pulldown:Pullup
2
2
PIN ASSIGNMENT
The Preliminary Information presented herein represents a product in pre-production. The noted characteristics are based on initial product characterization
and/or qualification. Integrated Device Technology, Incorporated (IDT) reserves the right to change any circuitry or specifications without notice.
