mk2069-03 Integrated Device Technology, mk2069-03 Datasheet - Page 11

• Manufacturer Part Number: mk2069-03
• Description: Vcxo-based Clock Translator With High Multiplication
• Manufacturer: Integrated Device Technology

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This above set of requirements is served by the circuit
illustrated in the Recommended Power Supply Connection
(next page). The main features of this circuit are as follows:
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IDT™ / ICS™ VCXO-BASED CLOCK TRANSLATOR WITH HIGH MULTIPLICATION 11
MK2069-03
VCXO-BASED CLOCK TRANSLATOR WITH HIGH MULTIPLICATION
Each VDD pin must be decoupled individually to prevent
power supply noise generated by one device circuit block
from interfering with another circuit block.
Clock noise from device VDD pins must not get onto the
PCB power plane or system EMI problems may result.
Only one connection is made to the PCB power plane.
The capacitors and ferrite chip (or ferrite bead) on the
common device supply form a lowpass ‘pi’ filter that
remove noise from the power supply as well as clock
noise back toward the supply. The bulk capacitor should
be a tantalum type, 1 F minimum. The other capacitors
should be ceramic type.
The power supply traces to the individual VDD pins
should fan out at the common supply filter to reduce
interaction between the device circuit blocks.
The decoupling capacitors at the VDD pins should be
ceramic type and should be as close to the VDD pin as
possible. There should be no via’s between the
decoupling capacitor and the supply pin.
Recommended Power Supply Connection
Series Termination Resistor
Output clock PCB traces over 1 inch should use series
termination to maintain clock signal integrity and to reduce
EMI. To series terminate a 50 trace, which is a commonly
used PCB trace impedance, place a 33 resistor in series
with the clock line as close to the clock output pin as
possible. The nominal impedance of the clock output is 20 .
Quartz Crystal
The MK2069-03 operates by phase-locking the VCXO
circuit to the input signal at the selected ICLK input. The
VCXO consists of the external crystal and the integrated
VCXO oscillator circuit. To achieve the best performance
and reliability, a crystal device with the recommended
parameters must be used, and the layout guidelines
discussed in the following section must be followed.
The frequency of oscillation of a quartz crystal is determined
by its cut and by the load capacitors connected to it. The
MK2069-03 incorporates variable load capacitors on-chip
which “pull” or change the frequency of the crystal. The
crystals specified for use with the MK2069-03 are designed
to have zero frequency error when the total of on-chip +
stray capacitance is 14pF. To achieve this, the layout should
use short traces between the MK2069-03 and the crystal.
Connection Via to 3.3V
Power Plane
Ferrite
Chip
VCXO AND SYNTHESIZER
MK2069-03
VDD
Pin
VDD
Pin
VDD
Pin
VDD
Pin
REV J 030906