MK3721
Low Cost 3.3 Volt VCXO
MDS 3721 B
1
Revision 082800
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)295-9800tel www.icst.com
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Block Diagram
Description
Features
The MK3721 is ICS/MicroClock's lowest cost,
low jitter, high performance 3.3 volt VCXO
designed to replace expensive VCXO modules.
The on-chip Voltage Controlled Crystal Oscillator
accepts a 0 to 3.3 V input voltage to cause the
output clocks to vary by 100 ppm. Using
ICS/MicroClock's patented VCXO techniques,
the device uses an inexpensive external pullable
crystal in the range of 16.2 - 28 MHz to produce a
VCXO output clock at that same frequency.
ICS/MicroClock manufactures the largest variety
of Set-Top Box and multimedia clock synthesizers
for all applications. If more clock outputs are
needed, see the MK3732 or MK377x family of
parts. Consult ICS/MicroClock to eliminate
VCXOs, crystals and oscillators from your board.
Packaged in 8 pin SOIC
3.3 V operating voltage
16.2 MHz to 28 MHz operation
Uses an inexpensive external crystal
On-chip VCXO (patented) with pull range of
200 ppm (minimum)
VCXO tuning voltage of 0 to 3.3 V
12 mA output drive capability at TTL levels
Advanced, low power, sub-micron CMOS process
For frequencies between 8 MHz to 16 MHz, use
the MK3711A. For frequencies between 1 MHz
and 8 MHz, use the MK3713. For higher than
28 MHz, use the MK3732-05
Voltage
Controlled
Crystal
Oscillator
16.2 -28 MHz
pullable crystal
X1
X2
VIN
Output
Buffer
16.2 - 28 MHz Clock
(REFOUT)
MK3721
Low Cost 3.3 Volt VCXO
MDS 3721 B
2
Revision 082800
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)295-9800tel www.icst.com
I C R O
C
LOC K
Pin Descriptions
Pin Assignment
Number
Name
Description
1
X1
Crystal connection. Connect to a pullable 16.2 - 28 MHz crystal.
2
VDD
VDD. Connect to + 3.3 V.
3
VIN
Voltage input to VCXO. Zero to 3.3 V analog input which controls the frequency of the VCXO.
4
GND
Connect to ground.
5
DC
Don't Connect anything to this pin.
6
REFOUT VCXO CMOS level clock output matches the nominal frequency of the crystal.
7
DC
Don't Connect anything to this pin.
8
X2
Crystal connection. Connect to a pullable 16.2 - 28 MHz crystal.
8 pin (150 mil) SOIC
MK3721
1
8
2
3
4
7
6
5
X2
X1
GND
VDD
DC
VIN
DC
REFOUT (VCXO)
Crystal Specifications
Correlation (load) capacitance
14 pF
Initial accuracy
20 ppm maximum
Drift over temperature and aging
50 ppm maximum
C0/C1 ratio
240 maximum
ESR
35
maximum
MK3721
Low Cost 3.3 Volt VCXO
MDS 3721 B
3
Revision 082800
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)295-9800tel www.icst.com
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Parameter
Conditions
Minimum
Typical
Maximum
Units
ABSOLUTE MAXIMUM RATINGS (note 1)
ABSOLUTE MAXIMUM RATINGS (note 1)
Supply voltage, VDD
Referenced to GND
7
V
Inputs and Clock Outputs
Referenced to GND
-0.5
VDD+0.5
V
Ambient Operating Temperature
0
70
C
Soldering Temperature
Max of 10 seconds
260
C
Storage temperature
-65
150
C
DC CHARACTERISTICS (VDD = 3.3 V unless noted)
DC CHARACTERISTICS (VDD = 3.3 V unless noted)
Operating Voltage, VDD
3.15
3.45
V
Output High Voltage, VOH
IOH=-12mA
2.4
V
Output Low Voltage, VOL
IOL=12mA
0.4
V
Output High Voltage, VOH, CMOS level
IOH=-4mA
VDD-0.4
V
Operating Supply Current, IDD
No Load
4
mA
Short Circuit Current
50
mA
VIN, VCXO control voltage
0
3.3
V
AC CHARACTERISTICS (VDD = 3.3 V unless noted)
AC CHARACTERISTICS (VDD = 3.3 V unless noted)
Input Crystal Frequency
16.2
28
MHz
Input Crystal Accuracy
30
ppm
Output Clock Rise Time
0.8 to 2.0V
1.5
ns
Output Clock Fall Time
2.0 to 0.8V
1.5
ns
Output Clock Duty Cycle
At VDD/2
40
50
60
%
Maximum Absolute Jitter, short term
55
ps
Output frequency pullability, note 2
0V
VIN
3.3 V
100
ppm
Electrical Specifications
Notes:
1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged
exposure to levels above the operating limits but below the Absolute Maximums may affect device reliability.
2. With a ICS/MicroClock approved pullable crystal.
External Components
The MK3721 requires a minimum number of external components for proper operation. A decoupling
capacitor of 0.01F should be connected between VDD and GND on pins 2 and 4, as close to the
MK3721 as possible. A series termination resistor of 33
may be used for the clock output. The input
crystal must be connected as close to the chip as possible. The input crystal should be a parallel mode,
pullable, AT cut, with 14 pF load capacitance. See previous page for crystal specifications. Consult ICS for
recommended suppliers. IMPORTANT - read application note MAN05 before laying out the PCB.
MK3721
Low Cost 3.3 Volt VCXO
MDS 3721 B
4
Revision 082800
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA 95126 (408)295-9800tel www.icst.com
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While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems Incorporated (ICS) assumes no responsibility for either its
use or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is
intended for use in normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary
environmental requirements are not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does
not authorize or warrant any ICS product for use in life support devices or critical medical instruments.
Ordering Information
Part/Order Number
Marking
Shipping packaging
Package
Temperature
MK3721S
MK3721S
tubes
8 pin SOIC
0-70 C
MK3721STR
MK3721S
tape and reel
8 pin SOIC
0-70 C
C
A
B
D
E
H
e
A1
L
Package Outline and Package Dimensions
(
For current dimensional specifications, see JEDEC Publication No. 95.)
8 pin SOIC
Inches
Inches
Millimeters
Millimeters
Symbol
Min
Max
Min
Max
A
0.0532
0.0688
1.35
1.75
A1
0.0040
0.0098
0.10
0.24
B
0.0130
0.0200
0.33
0.51
C
0.0075
0.0098
0.19
0.24
D
0.1890
0.1968
4.80
5.00
E
0.1497
0.1574
3.80
4.00
e
.050 BSC
.050 BSC
1.27 BSC
1.27 BSC
H
0.2284
0.2440
5.80
6.20
h
0.0099
0.0195
0.25
0.50
L
0.0160
0.0500
0.41
1.27
INDEX
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