ICS8745B Datasheet, PDF (9/15 Pages) Integrated Circuit Systems – 1:5 DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR

Integrated
Circuit
Systems, Inc.
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS8745B provides sepa-
rate power supplies to isolate any high switching
noise from the outputs to the internal PLL. V_DD, V_DDA, and V_DDO
should be individually connected to the power supply
plane through vias, and bypass capacitors should be
used for each pin. To achieve optimum jitter performance,
power supply isolation is required. Figure 3 illustrates how
a 10Ω resistor along with a 10μF and a .01μF bypass
capacitor should be connected to each V pin.
DDA
ICS8745B
1:5 DIFFERENTIAL-TO-LVDS
ZERO DELAY CLOCK GENERATOR
3.3V
V
DD
.01μF 10Ω
V_DDA
.01μF
10 μF
FIGURE 3. POWER SUPPLY FILTERING
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 4A to 4D 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 4A, 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 4A. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
ICS HIPERCLOCKS LVHSTL DRIVER
FIGURE 4B. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL 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
3.3V
Zo = 50 Ohm
LVDS_Driv er
R1
100
Zo = 50 Ohm
3.3V
CLK
nCLK _{Receiv er}
FIGURE 4C. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
FIGURE 4D. HIPERCLOCKS CLK/NCLK INPUT DRIVEN BY
3.3V LVDS DRIVER
8745BY
www.icst.com/products/hiperclocks.html
9
REV. B DECEMBER 2, 2004