MK3721 - Integrated Circuit Systems, Inc.

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

ICROCLOCK

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

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

ICROCLOCK

Pin Descriptions

Pin Assignment

Number Name Description

1X1 Crystal connection. Connect to a pullable 16.2 - 28 MHz crystal.

2VDD VDD. Connect to + 3.3 V.

3VIN Voltage input to VCXO. Zero to 3.3 V analog input which controls the frequency of the VCXO.

4GND Connect to ground.

5 DC Don't Connect anything to this pin.

6REFOUT VCXO CMOS level clock output matches the nominal frequency of the crystal.

7DC Don't Connect anything to this pin.

8X2 Crystal connection. Connect to a pullable 16.2 - 28 MHz crystal.

8 pin (150 mil) SOIC

MK3721

1 8

GND

VDD

VIN

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 Ω 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

ICROCLOCK

Parameter Conditions Minimum Typical Maximum Units

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)

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)

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 0.01µF 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.

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

ICROCLOCK

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

E H

Package Outline and Package Dimensions

(For current dimensional specifications, see JEDEC Publication No. 95.)

8 pin SOIC

Inches

Millimeters

Symbol Min Max Min Max

A0.0532 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

.050 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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