FEMTOCLOCKS™ CRYSTAL-TO-LVDS

FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER

ICS844256

1

ICS844256BG REV. B NOVEMBER

19, 2007

PRELIMINARY

The ICS844256 is a Cr ystal-to-LVDS Clock

Synthesizer/Fanout Buffer designed for

SONET

and Gigabit Ether net applications and is a

member of the HiperClockS™ family of High

Perfor mance Clock Solutions from IDT. The

output frequency can be set using the frequency select

pins and a 25MHz cr ystal for Ether net frequencies, or a

19.44MHz crystal for SONET. The low phase noise character-

istics of the ICS844256 make it an ideal clock for these

demanding applications.

• 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

• Available in both standard (RoHS 5) and lead-free (RoHS 6)

packages

HiPerClockS™

ICS

Q0

nQ2

Q2

nQ1

Q1

nQ0

Q0

PLL_BYPASS

FB_SEL

1

2

3

4

5

6

7

8

9

10

11

12

Q3

nQ3

Q4

nQ4

Q5

nQ5

N_SEL1

GND

GND

N_SEL0

XTAL_OUT

XTAL_IN

OSC

PLL

Feedback

Divider

Output

Divider

1

0

XTAL_IN

XTAL_OUT

PLL_BYPASS

nQ0

24

23

22

21

20

19

18

17

16

15

14

13

Q1

nQ1

Q2

nQ2

Q3

nQ3

Q4

nQ4

Q5

nQ5

FB_SEL

N_SEL1

N_SEL0

Pullup

Pulldown

Pullup

Pullup

ICS844256

24-Lead TSSOP, E-Pad

4.40mm x 7.8mm x 0.90mm

body package

G Package

Top View

s

t

u

p

n

In

o

i

t

c

n

u

F

L

E

S

_

B

F1

L

E

S

_

N0

L

E

S

_

Ne

d

i

v

i

D

Me

d

i

v

i

D

NN

/

M

00

0

5

21

5

2

00

1

5

22

5

.

2

1

01

0

5

24

5

2

.

6

01

1

5

25

5

10

0

2

31

2

3

10

1

2

32

6

1

11

0

2

34

8

11

1

2

38

4

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.