ICS841S012DKI REVISION A JULY 20, 2009

10

©2009 Integrated Device Technology, Inc.

ICS841S012DI Data Sheet

CRYSTAL-TO-0.7V DIFFERENTIAL HCSL/LVCMOS FREQUENCY SYNTHESIZER

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

vulnerable to random noise. To achieve optimum jitter perfor-

mance, power supply isolation is required. The ICS841S012DI

provides separate power supplies to isolate any high switching

noise from the outputs to the internal PLL. V

V

plane through vias, and 0.01µF bypass capacitors should be used

for each pin.

Figure 1 illustrates this for a generic V

also shows that V

along with a 10µF bypass capacitor be connected to the V

10

Ω

V

DDA

10

μF

.01

μF

3.3V

.01

μF

V

DD

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.

For applications not requiring the use of the reference clock,

it can be left floating. Though not required, but for additional

protection, a 1k

Ω resistor can be tied from the REF_IN to ground.

All control pins have internal pull-ups or pull-downs; additional

resistance is not required but can be added for additional

protection. A 1k

Ω resistor can be used.

All unused LVCMOS output can be left floating. We recommend

that there is no trace attached.

All unused differential outputs 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.