mk2069-04 Integrated Device Technology, mk2069-04 Datasheet - Page 11

• Manufacturer Part Number: mk2069-04
• Description: Vcxo-based Universal Clock Translator
• Manufacturer: Integrated Device Technology

Lock Detection Circuit Diagram
If the lock detection circuit is not used, the LDR output may
remain unconnected, however the LDC input should be tied
high or low. If the PCB was designed to accommodate the
RLD and CLD components but the LD output will not be
used, RLD can remain unstuffed and CLD can be replaced
with a resistor (< 10 kohm).
Power Supply Considerations
As with any integrated clock device, the MK2069-04 has a
special set of power supply requirements:
•
•
•
This above set of requirements is served by the circuit
illustrated in the Recommended Power Supply Connection
IDT™ / ICS™ VCXO-BASED UNIVERSAL CLOCK TRANSLATOR
MK2069-04
VCXO-BASED UNIVERSAL CLOCK TRANSLATOR
The feed from the system power supply must be filtered
for noise that can cause output clock jitter. Power supply
noise sources include the system switching power supply
or other system components. The noise can interfere with
device PLL components such as the VCO or phase
detector.
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.
D e te c to r
D iv id e r
O u tp u t
O u tp u t
P h a s e
V C X O
E rro r
F V
C L D
L o c k D e te ctio n C irc u it
R L D
L D R
(8 u p , 1 d o w n )
Q u a lific a tio n
L D C
C o u n te r
L o c k
R E S E T
In p u t T h res h o ld
se t to V D D /2
L D
O E L
11
(next page). The main features of this circuit are as follows:
•
•
•
•
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 50Ω trace, which is a commonly
used PCB trace impedance, place a 33Ω resistor in series
with the clock line as close to the clock output pin as
possible. The nominal impedance of the clock output is 20Ω.
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 µF 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.
Connection Via to 3.3V
Power Plane
Ferrite
Chip
VCXO AND SYNTHESIZER
MK2069-04
REV G 090905
VDD
Pin
VDD
Pin
VDD
Pin
VDD
Pin