ICS87951I Datasheet, PDF (9/14 Pages) Integrated Device Technology – LOW SKEW, 1-TO-9 DIFFERENTIAL-TO-LVCMOS/LVTTL ZERO DELAY BUFFER

ICS87951I
LOW SKEW, 1-TO-9
DIFFERENTIAL-TO-LVCMOS/LVTTL ZERO DELAY BUFFER
DIFFERENTIAL CLOCK INPUT INTERFACE
The CLK1 /nCLK1 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
interface examples for the CLK1/nCLK1 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
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
Zo = 50 Ohm
LVPECL
3.3V
CLK
nCLK _HiPerClockS
Input
R1
R2
50
50
R3
50
FIGURE 3A. CLK/NCLK INPUT DRIVEN BY
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. 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. CLK/NCLK INPUT DRIVEN BY
3.3V LVPECL DRIVER
FIGURE 3D. CLK/NCLK INPUT DRIVEN BY
3.3V LVDS DRIVER
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS
INPUTS:
OUTPUTS:
CLK INPUT:
For applications not requiring the use of a clock input, it can
be left floating. Though not required, but for additional
protection, a 1kΩ resistor can be tied from the CLK input to
ground.
LVCMOS OUTPUT:
All unused LVCMOS output can be left floating. We
recommend that there is no trace attached.
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.idt.com
9
REV. C JULY 17, 2010