ICS8430S07I datasheet(13/27 Pages) RENESAS

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ICS8430S07AKI REVISION A SEPTEMBER 3, 2009

ICS8430S07I Data Sheet

CLOCK GENERATOR FOR CAVIUM PROCESSORS

Power Supply Filtering Technique

As in any high speed analog circuitry, the power supply pins are

vulnerable to random noise. To achieve optimum jitter perform ance,

power supply isolation is required. The ICS8430S07I provides

separate power supplies to isolate any high switching noise from the

outputs to the internal PLL. VDD, VDDA and VDDO_X should be

individually connected to the power supply plane through vias, and

0.01µF bypass capacitors should be used for each pin. Figure 2

illustrates this for a generic VDD pin and also shows that VDDA

requires that an additional 10

Ω resistor along with a 10µF bypass

capacitor be connected to the VDDA pin.

Figure 2. Power Supply Filtering

Recommendations for Unused Input and Output Pins

Inputs:

CLK/nCLK Inputs

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 1k

Ω resistor can be tied from CLK to ground.

Crystal Inputs

For applications not requiring the use of the crystal oscillator input,

both XTAL_IN and XTAL_OUT can be left floating. Though not

required, but for additional protection, a 1k

Ω resistor can be tied from

XTAL_IN to ground.

LVCMOS Control Pins

All control pins have internal pulldowns; additional resistance is not

required but can be added for additional protection. A 1k

Ω resistor

can be used.

Outputs:

LVPECL Outputs

The unused LVPECL output can be left floating. We recommend that

there is no trace attached. Both sides of the differential output pair

should either be left floating or terminated.

LVCMOS Outputs

All unused LVCMOS output can be left floating. There should be no

trace attached.

VDD

VDDA

3.3V

Ω

10µF

.01µF

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