DATASHEET
LOW COST 54 MHZ 3.3 VOLT VCXO
Description
The MK3754D and MK3754B are drop-in replacements for
the MK3754S device. Compared to these earlier devices
the MK3754D and MK3754B offer a wider operating
frequency range and improved power supply noise
rejection.
The MK3754 is ICS’ lowest cost, low jitter, high
performance 3.3 Volt VCXO and PLL clock synthesizer
designed to replace expensive 54 MHz VCXOs. The
on-chip Voltage Controlled Crystal Oscillator accepts a 0 to
3.3 V input voltage to vary the output clocks by ±100 ppm.
Using ICS’ patented VCXO and analog/digital
Phase-Locked Loop (PLL) techniques, the device uses an
inexpensive external 13.5 MHz pullable crystal input to
produce a 54 MHz output clock.
The MK3754D exhibits a moderate VCXO gain of
120 ppm/V typical, when used with a high quality external
pullable quartz crystal. The MK3754B offers a higher
VCXO gain of 150 ppm/V. The higher intrinsic VCXO gain
of the MK3754B may help compensate for the reduced
pullability of a low quality crystal used in some applications.
However, higher VCXO gain may also increase clock output
phase noise.
MK3754
The frequency of the on-chip VCXO is adjusted by an
external control voltage input into pin VIN. Because VIN is a
high impedance input, it can be driven directly from an
PWM RC integrator circuit. Frequency output increases
with VIN voltage input. The usable range of VIN is 0 to 3 V.
Features
•
MK3754D and MK3754B are drop-in upgrades to the
earlier MK3754S device
•
•
•
•
•
Packaged in 8-pin SOIC
Available in Pb (lead) free package
Operating voltage of 3.3 V
Uses an inexpensive 13.500 MHz external crystal
On-chip VCXO (patented) with pull range of 200 ppm
(minimum)
•
VCXO turning voltage of 0 to 3.3V
•
12 mA output drive capability at TTL levels
•
Advanced, low power, sub-micron CMOS process
MK3754D is Recommended for New Designs.
Block Diagram
VDD
V IN
13.5 M H z
P ullable
C rystal
X1
V oltage
C ontrolled
C rystal
O scillator
X2
P LL/C lock
S ynthesis
C ircuitry
54 M H z
GND
IDT™ / ICS™
LOW COST 54 MHZ 3.3 VOLT VCXO
1
MK3754
REV H 072805
MK3754
LOW COST 54 MHZ 3.3 VOLT VCXO
VCXO AND MULTIPLIER
Pin Assignment
X1
VDD
VIN
GND
1
2
3
4
MK3754S
MK3754B
MK3754D
8 Pin (150 mil) SOIC
8
7
6
5
X2
GND
CLK
VDD
Pin Descriptions
Pin
Number
1
2
3
4
5
6
7
8
Pin
Name
XI
VDD
VIN
GND
VDD
CLK
GND
X2
Pin
Type
Input
Power
Input
Power
Power
Power
Input
Pin Description
Crystal connection. Connect to the external pullable crystal.
Connect to +3.3 V (0.01uf decoupling capacitor recommended).
Voltage input to VCXO -- 0 to 3.3 V analog input which controls the
oscillation frequency of the VCXO.
Connect to ground.
Connect to +3.3 V (0.01uf decoupling capacitor recommended).
Connect to ground.
Crystal connection. Connect to the external pullable crystal.
Output 54 MHz clock output.
IDT™ / ICS™
LOW COST 54 MHZ 3.3 VOLT VCXO
2
MK3754
REV H 072805
MK3754
LOW COST 54 MHZ 3.3 VOLT VCXO
VCXO AND MULTIPLIER
External Component Selection
The MK3754 requires a minimum number of external
components for proper operation.
as possible and should be on the same side of the PCB as
the MK3754. There should be no via’s between the crystal
pins and the X1 and X2 device pins. There should be no
signal traces underneath or close to the crystal.
Decoupling Capacitor
A decoupling capacitor of 0.01 µF must be connected
between VDD (pin 2) and GND (pin 4), as close to these
pins as possible. For optimum device performance, the
decoupling capacitor should be mounted on the component
side of the PCB. Avoid the use of vias in the decoupling
circuit.
Crystal Tuning Load Capacitors
The crystal traces should include pads for small fixed
capacitors, one between X1 and ground, and another
between X2 and ground. Stuffing of these capacitors on the
PCB is optional. The need for these capacitors is
determined at system prototype evaluation, and is
influenced by the particular crystal used (manufacture and
frequency) and by PCB layout. The typical required
capacitor value is 1 to 4 pF.
The procedure for determining the value of these capacitors
can be found in application note MAN05.
Series Termination Resistor
When the PCB trace between the clock output (CLK, pin 5)
and the load is over 1 inch, series termination should be
used. To series terminate a 50Ω trace (a commonly used
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.
Quartz Crystal
The MK3754 VCXO function consists of the external crystal
and the integrated VCXO oscillator circuit. To assure the
best system performance (frequency pull range) and
reliability, a crystal device with the recommended
parameters (shown below) must be used, and the layout
guidelines discussed in the following section shown 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
MK3754 incorporates on-chip variable load capacitors that
“pull” (change) the frequency of the crystal. The crystal
specified for use with the MK3754 is designed to have zero
frequency error when the total of on-chip + stray
capacitance is
14 pF.
Recommended Crystal Parameters:
Initial Accuracy at 25
°
C
Temperature Stability
Aging
Load Capacitance
Shunt Capacitance, C0
C0/C1 Ratio
Equivalent Series Resistance
±20 ppm
±30 ppm
±20 ppm
14 pf
7 pF Max
250 Max
35
Ω
Max
The external crystal must be connected as close to the chip
IDT™ / ICS™
LOW COST 54 MHZ 3.3 VOLT VCXO
3
MK3754
REV H 072805
MK3754
LOW COST 54 MHZ 3.3 VOLT VCXO
VCXO AND MULTIPLIER
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK3754. These ratings, which are
standard values for ICS commercially rated parts, are stress ratings only. Functional operation of the device at
these or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Item
Supply Voltage, VDD
All Inputs and Outputs
Ambient Operating Temperature
Storage Temperature
Soldering Temperature
7V
Rating
-0.5V to VDD+0.5V
0 to +70°C
-65 to +150°C
260°C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Reference crystal parameters
Min.
0
+3.15
Typ.
–
Max.
+70
+3.45
Units
°C
V
Refer to page 3
IDT™ / ICS™
LOW COST 54 MHZ 3.3 VOLT VCXO
4
MK3754
REV H 072805
MK3754
LOW COST 54 MHZ 3.3 VOLT VCXO
VCXO AND MULTIPLIER
DC Electrical Characteristics
VDD=3.3 V ±5%
, Ambient temperature 0 to +70°C, unless stated otherwise
Parameter
Operating Voltage
Output High Voltage
Output Low Voltage
Output High Voltage (CMOS
Level)
Operating Supply Current
Short Circuit Current
VIN, VCXO Control Voltage
Symbol
VDD
V
OH
V
OL
V
OH
IDD
I
OS
V
IA
Conditions
I
OH
= -12 mA
I
OL
= 12 mA
I
OH
= -4 mA
No load
Min.
3.15
2.4
Typ.
Max.
3.45
0.4
Units
V
V
V
V
VDD-0.4
9
±50
0
3.3
mA
mA
V
AC Electrical Characteristics
VDD = 3.3 V ±5%
, Ambient Temperature 0 to +70° C, unless stated otherwise
Parameter
Crystal Pullability
MK3754D and
MK3754B
MK3754S
VCXO Gain
MK3754D
MK3754B
MK3754S
Output Rise Time
Output Fall Time
Output Clock Duty Cycle
Maximum Output Jitter,
short term
t
OR
t
OF
t
D
t
J
VIN = VDD/2 + 1 V, Note 1
VIN = VDD/2 + 1 V, Note 1
VIN = VDD/2 + 1 V, Note 1
0.8 to 2.0 V, C
L
=15 pF
2.0 to 0.8 V, C
L
=15 pF
Measured at 1.4 V, C
L
=15 pF
C
L
=15 pF
45
50
100
120
150
100
1.5
1.5
55
ppm/V
ppm/V
ppm/V
ns
ns
%
ps
F
P
F
P
0V< VIN < 3.3 V, Note 1
0V< VIN < 3.3 V, Note 1
+ 115
+ 100
ppm
ppm
Symbol
Conditions
Min.
Typ.
Max. Units
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
IDT™ / ICS™
LOW COST 54 MHZ 3.3 VOLT VCXO
5
MK3754
REV H 072805
嵌入式系统
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