ICS845204 Datasheet, PDF (1/13 Pages) Integrated Device Technology – CRYSTAL-TO-MLVDS PCI EXPRESS™ CLOCK SYNTHESIZER W/SPREAD SPECTRUM

ADVANCE INFORMATION
CRYSTAL-TO-MLVDS PCI EXPRESS™
CLOCK SYNTHESIZER W/SPREAD SPECTRUM
ICS845204
General Description
The ICS845204 is a 4 output PCI Express clock
ICS
synthesizer optimized to generate low jitter PCI
HiPerClockS™ _{Express™ 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 M-LVDS clocks at either 25MHz,
100MHz, 125MHz or 250MHz. The ICS845204 uses a low jitter
VCO that easily meets PCI Express jitter requirements and is
packaged in a 32-pin VFQFN package.
Pin Assignment
OE0
VDD
nQ3
Q3
VDDO
nc
FSEL0
nc
32 31 30 29 28 27 26 25
1
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9 10 11 12 13 14 15 16
nc
nc
GND
Q2
nQ2
SSC1
nc
GND
Features
• Four differential spread spectrum clock outputs
• Each output can be individually disabled by separate
output-enable inputs
• Crystal oscillator interface designed for 18pF,
25MHz parallel resonant crystal
• Supports the following output frequencies:
25MHz, 100MHz, 125MHz or 250MHz
• VCO range: 250MHz - 700MHz
• Supports SSC downspread at 0.05% and -0.75%, centerspread
at ±0.25% and no spread options
• Cycle-to-cycle jitter: 50ps (maximum) design target
• Period jitter, RMS: TBD
• Full 3.3V output supply mode
• 0°C to 70°C ambient operating temperature
• Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
ICS845204
32 Lead VFQFN
5mm x 5mm x 0.925mm
package body
K Package
Top View
Block Diagram
25MHz
XTAL_IN
OSC
XTAL_OUT
Phase
Detector
VCO
250-700MHz
Feedback Divider
÷20
0 0 PLL Bypass
0 1 ÷5
1 0 ÷4
1 1 ÷2
2
SSC[1:0] ^{Pullup:Pullup}
Default = 100MHz
2
FSEL[1:0] ^{Pulldown:Pullup}
Spread Spectrum
Control
Q0
nQ0
Pullup _OE0
Q1
nQ1
Pullup _OE1
Q2
nQ2
Pullup _OE2
Q3
nQ3
Pullup _OE3
The Advance Information presented herein represents a product that is developmental or prototype. The noted characteristics are design targets. Integrated
Device Technologies, Inc. (IDT) reserves the right to change any circuitry or specifications without notice.
IDT™ / ICS™ M-LVDS CLOCK SYNTHESIZER
1
ICS845204AK SEPTEMBER 25, 2007