ICS87951I
LOW SKEW, 1-TO-9
DIFFERENTIAL-TO-LVCMOS/LVTTL ZERO DELAY BUFFER
Integrated
Circuit
Systems, Inc.
DIFFERENTIAL CLOCK INPUT INTERFACE
The CLK1 /nCLK1 accepts LVDS, LVPECL, LVHSTL, SSTL, here are examples only. Please consult with the vendor of the
HCSL and other differential signals. Both VSWING and VOH must driver component to confirm the driver termination requirements.
meet theVPP andVCMR input requirements. Figures 4A to 4D show For example in Figure 3A, the input termination applies for ICS
interface examples for the HiPerClockS CLK1/nCLK1 input driven HiPerClockS LVHSTL drivers. If you are using an LVHSTL driver
by the most common driver types.The input interfaces suggested from another vendor, use their termination recommendation.
3.3V
3.3V
3.3V
1.8V
Zo = 50 Ohm
CLK
Zo = 50 Ohm
CLK
Zo = 50 Ohm
nCLK
Zo = 50 Ohm
HiPerClockS
Input
LVPECL
nCLK
HiPerClockS
Input
LVHSTL
R1
50
R2
50
ICS
HiPerClockS
R1
50
R2
50
LVHSTL Driver
R3
50
FIGURE 3A. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
ICS HIPERCLOCKS LVHSTL DRIVER
FIGURE 3B. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
3.3V
3.3V
3.3V
3.3V
Zo = 50 Ohm
3.3V
R3
125
R4
125
LVDS_Driver
Zo = 50 Ohm
Zo = 50 Ohm
CLK
CLK
R1
100
nCLK
Receiv er
nCLK
HiPerClockS
Input
Zo = 50 Ohm
LVPECL
R1
84
R2
84
FIGURE 3C. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
FIGURE 3D. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVDS DRIVER
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS
INPUTS:
CLK INPUT:
OUTPUTS:
LVCMOS OUTPUT:
For applications not requiring the use of a clock input, it can All unused LVCMOS output can be left floating. We
be left floating. Though not required, but for additional recommend that there is no trace attached.
protection, a 1kΩ resistor can be tied from the CLK input to
ground.
CLK/nCLK INPUT:
For applications not requiring the use of the differential input,
both CLK and nCLK can be left floating. Though not required,
but for additional protection, a 1kΩ resistor can be tied from
CLK to ground.
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.
87951AYI
www.icst.com/products/hiperclocks.html
REV.B NOVEMBER 23, 2005
9
SPECTRUM [ SPECTRUM MICROWAVE, INC. ]
