ICS874002 Datasheet, PDF (7/10 Pages) Integrated Circuit Systems – PCI EXPRESS JITTER ATTENUATOR

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS874002
PCI EXPRESS™
JITTER ATTENUATOR
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 inter-
face examples for the HiPerClockS CLK/nCLK input driven by
the most common driver types. The input interfaces suggested
here are 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
Zo = 50 Ohm
Zo = 50 Ohm
LVHSTL
ICS
HiPerClockS
LVHSTL Driver
3.3V
CLK
nCLK _HiPerClockS
Input
R1
R2
50
50
3.3V
Zo = 50 Ohm
LVPECL
Zo = 50 Ohm
3.3V
CLK
nCLK _HiPerClockS
Input
R1
R2
50
50
R3
50
FIGURE 3A. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
ICS HIPERCLOCKS LVHSTL DRIVER
3.3V
Zo = 50 Ohm
LVPECL
Zo = 50 Ohm
3.3V
R3
R4
125
125
3.3V
CLK
nCLK _HiPerClockS
Input
R1
R2
84
84
FIGURE 3B. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
3.3V
Zo = 50 Ohm
LVDS_Driv er
R1
100
Zo = 50 Ohm
3.3V
CLK
nCLK _{Receiv er}
FIGURE 3C. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
FIGURE 3D. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVDS DRIVER
LVDS DRIVER TERMINATION
A general LVDS interface is shown in Figure 4. In a 100Ω
differential transmission line environment, LVDS drivers
require a matched load termination of 100Ω across near
the receiver input. For a multiple LVDS outputs buffer, if only
partial outputs are used, it is recommended to terminate the
un-used outputs.
3.3V
LVDS_Driv er
3.3V
+
R1
100
-
100 Ohm Differiential Transmission Line
874002AG
FIGURE 4. TYPICAL LVDS DRIVER TERMINATION
www.icst.com/products/hiperclocks.html
7
REV. A JANUARY 19, 2005