IDT
™
/ ICS
™
PCI EXPRESS™ JITTER ATTENUATOR 8 ICS874003AG-02 REV A AUGUST 29, 2006
ICS874003-02
PCI EXPRESS™ JITTER ATTENUATOR
FIGURE 3C. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
FIGURE 3B. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
FIGURE 3D. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVDS DRIVER
3.3V
R1
50
R3
50
Zo = 50 Ohm
LVPECL
Zo = 50 Ohm
HiPerClockS
CLK
nCLK
3.3V
Input
R2
50
Zo = 50 Ohm
Input
HiPerClockS
CLK
nCLK
3.3V
R3
125
R2
84
Zo = 50 Ohm
3.3V
R4
125
LVPECL
R1
84
3.3V
DIFFERENTIAL CLOCK INPUT INTERFACE
The CLK /nCLK accepts LVDS, LVPECL, LVHSTL, SSTL, HCSL
and other differential signals. Both V
SWING
and V
OH
must meet the
V
PP
and V
CMR
input requirements. Figures 3A to 3D show interface
examples for the HiPerClockS CLK/nCLK input driven by the most
common driver types. The input interfaces suggested here are
FIGURE 3A. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
ICS HIPERCLOCKS LVHSTL DRIVER
examples only. Please consult with the vendor of the driver
component to confirm the driver termination requirements. For
example in
Figure 3A,
the input termination applies for ICS
HiPerClockS LVHSTL drivers. If you are using an LVHSTL driver
from another vendor, use their termination recommendation.
1.8V
R2
50
Input
LVHSTL Driver
ICS
HiPerClockS
R1
50
LVHSTL
3.3V
Zo = 50 Ohm
Zo = 50 Ohm
HiPerClockS
CLK
nCLK
Zo = 50 Ohm
R1
100
3.3V
LVDS_Driv er
Zo = 50 Ohm
Receiv er
CLK
nCLK
3.3V
INPUTS:
LVCMOS CONTROL PINS:
All control pins have internal pull-ups or pull-downs; additional
resistance is not required but can be added for additional
protection. A 1kΩ resistor can be used.
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS
OUTPUTS:
LVDS
All unused LVDS output pairs can be either left floating or
terminated with 100Ω across. If they are left floating, we
recommend that there is no trace attached.
