ICS5310AI01L datasheet(9/15 Pages) ICST

9 / 15 page

85310AYI-01

www.icst.com/products/hiperclocks.html

REV. F JANUARY16, 2006

Integrated

Circuit

Systems, Inc.

ICS85310I-01

LOW SKEW, 1-TO-10

DIFFERENTIAL-TO-2.5V/3.3V ECL/LVPECL FANOUT BUFFER

CC - 2V

RTT

o = 50Ω

FOUT

FIN

RTT =

((V

OH + VOL) / (VCC – 2)) – 2

3.3V

125

o = 50Ω

FOUT

FIN

The clock layout topology shown below is a typical termina-

tion for LVPECL outputs. The two different layouts mentioned

are recommended only as guidelines.

FOUT and nFOUT are low impedance follower outputs that

generate ECL/LVPECL compatible outputs. Therefore, ter-

minating resistors (DC current path to ground) or current

sources must be used for functionality. These outputs are

designed to drive 50

Ω transmission lines. Matched imped-

ance techniques should be used to maximize operating

frequency and minimize signal distortion. Figures 3A and

3B show two different layouts which are recommended only

as guidelines. Other suitable clock layouts may exist and it

would be recommended that the board designers simulate

to guarantee compatibility across all printed circuit and clock

component process variations.

TERMINATION FOR LVPECL OUTPUTS

FIGURE 3B. LVPECL OUTPUT TERMINATION

FIGURE 3A. LVPECL OUTPUT TERMINATION

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