Datasheet MK3721S, MK3721STR Datasheet (ICST)

MK3721

Revision 082800

Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA • 95126• [phone]tel • www.icst.com

ICRO

C

LOCK

Description

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.

Low Cost 3.3 Volt VCXO

Features

• 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

Block Diagram

VIN

X1

16.2 -28 MHz
pullable crystal

X2

MDS 3721 B 1

Voltage

Controlled

Crystal

Oscillator

Output

Buffer

16.2 - 28 MHz Clock
(REFOUT)

MK3721

Revision 082800

Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA • 95126• [phone]tel • www.icst.com

Pin Assignment

Pin Descriptions

ICR O

C

LOCK

VDD

VIN

GND

Low Cost 3.3 Volt VCXO

MK3721

X1

1 8
2

3

4

7
6

5

8 pin (150 mil) SOIC

X2

DC
REFOUT (VCXO)

DC

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.

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 Ω maximum

MDS 3721 B 2

MK3721

Revision 082800

Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA • 95126• [phone]tel • www.icst.com

ABSOLUTE MAXIMUM RATINGS (note 1)

DC CHARACTERISTICS (VDD = 3.3 V unless noted)

AC CHARACTERISTICS (VDD = 3.3 V unless noted)

exposure to levels above the operating limits but below the Absolute Maximums may affect device reliability.

2. With a ICS/MicroClock approved pullable crystal.

ICR O

C

LOCK

Low Cost 3.3 Volt VCXO

Electrical Specifications

Parameter Conditions Minimum Typical Maximum Units

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

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

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

Notes: 1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged

External Components

The MK3721 requires a minimum number of external components for proper operation. A decoupling
capacitor of 0.01µF 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 Ω 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.

MDS 3721 B 3

MK3721

Revision 082800

Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA • 95126• [phone]tel • www.icst.com

Inches

Millimeters

ICR O

C

LOCK

Low Cost 3.3 Volt VCXO

Package Outline and Package Dimensions
(For current dimensional specifications, see JEDEC Publication No. 95.)

8 pin SOIC

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

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

AREA

A1

E H

D

A

C

e

B

L

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

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.

MDS 3721 B 4