ADVANCE INFORMATION

CRYSTAL-TO-MLVDS PCI EXPRESS™

CLOCK SYNTHESIZER W/SPREAD SPECTRUM

ICS845204

IDT™ / ICS™ M-LVDS CLOCK SYNTHESIZER

1

ICS845204AK SEPTEMBER 25, 2007

General Description

The ICS845204 is a 4 output PCI Express clock

synthesizer optimized to generate low jitter PCI

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.

Features

output-enable inputs

25MHz parallel resonant crystal

25MHz, 100MHz, 125MHz or 250MHz

at ±0.25% and no spread options

packages

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.

HiPerClockS™

ICS

Phase

Detector

VCO

250-700MHz

Feedback Divider

÷20

Spread Spectrum

Control

OSC

Q0

nQ0

OE0

Q1

nQ1

Q2

nQ2

Q3

nQ3

XTAL_IN

XTAL_OUT

SSC[1:0]

FSEL[1:0]

Pullup

Pullup

Pullup

Pullup

Default = 100MHz

25MHz

Pullup:Pullup

Pulldown:Pullup

2

2

OE1

OE2

OE3

0 0

PLL Bypass

0 1

÷5

1 0

÷4

1 1

÷2

9

10 11 12 13 14 15 16

32 31 30

29 28

27 26 25

1

2

3

4

5

6

7

8

24

23

22

21

20

19

18

17

OE0

nQ3

Q3

nc

FSEL0

nc

nc

nc

GND

Q2

nQ2

SSC1

nc

GND

Pin Assignment

ICS845204

32 Lead VFQFN

5mm x 5mm x 0.925mm

package body

K Package

Top View

Block Diagram