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MK2731-01
LOW COST VCXO
Description
The MK2731-01 is a low cost, low jitter, high-performance VCXO and PLL clock synthesizer designed to replace expensive discrete VCXOs, PLLs and oscillators. The on-chip Voltage Controlled Crystal Oscillator accepts a 0 to 3V input voltage to cause the output clocks to vary by 100 ppm. Using ICS's patented VCXO and analog Phase-Locked Loop (PLL) techniques, the device uses an inexpensive 10 MHz or 13.5 MHz pullable crystal input to produce two low skew output clocks. ICS manufactures a large variety of Set-Top Box and multimedia clock synthesizers for all applications. If more clock outputs are needed, see the MK277x family of parts. Consult ICS to eliminate VCXOs, crystals and oscillators from your board.
Features
* Packaged in 16-pin narrow SOIC * Uses an inexpensive 10 or 13.5 MHz crystal * On-chip VCXO (patented) with pull range of 200 ppm
(minimum)
* * * *
VCXO tuning voltage of 0 to 3 V Zero ppm synthesis error in all clocks Low skew output clocks - 1 ns maximum CMOS level outputs with 25 mA output drive capability at TTL levels
* Advanced, low power, sub-micron CMOS process * 5 V operating voltage
Block Diagram
S2:0 VIN X1
3
CLK1 PLL/Clock Synthesis Circuitry CLK2
10 MHz or 13.5 MHz Pullable Crystal
X2
Voltage Controlled Crystal Oscillator
OE (both outputs)
MDS 2731-01 E I n t e gra te d C i r c u i t S y s t e m s
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525 Race Stre et, San Jo se, CA 9 5126
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MK2731-01 LOW COST VCXO
Pin Assignment
X2 X1 VDD VIN GND GND OE CLK1 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VDD NC S2 VDD GND CLK2 S1 S0
Output Clock Select Table
Input S2
10 10 13.5 13.5 13.5 13.5 -- 13.5 0 0 0 0 1 1 1 1
S1
0 0 1 1 0 0 1 1
S0
0 1 0 1 0 1 0 1
CLK1
40 40 40 27 33.33 24.576 32
CLK2
80 OFF OFF 54 66.66 49.152 64
Test use
16-pin narrow (150 mil) SOIC
(All OFF outputs are stopped low)
Pin Descriptions
Pin Number
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Pin Name
X2 X1 VDD VIN GND GND OE CLK1 S0 S1 CLK2 GND VDD S2 NC VDD
Pin Type
Output Input Power Input Power Power Input Output Input Input Output Power Power Input -Power
Pin Description
Crystal connection. Connect to a 10 or 13.5 MHz pullable crystal. Crystal connection. Connect to a 10 or 13.5 MHz pullable crystal. Connect to +5 V. Voltage input to VCXO. Zero to 3 V signal which controls the VCXO frequency. Connect to ground. Connect to ground. Output Enable. Active high. Tri-states both outputs when low. Clock output 1 determined by status of S2, S1, and S0. See table above. Fixed Clock Select 0. Selects outputs per table above. Fixed Clock Select 1. Selects outputs per table above. Clock output 2 determined by status of S2, S1, and S0. See table above. Connect to ground. Connect to +5 V. Fixed Clock Select 2. Selects outputs per table above. No connect. Connect to +5 V.
MDS 2731-01 E In te grated Circuit Systems
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MK2731-01 LOW COST VCXO
External Component Selection
The MK2731-01 requires a minimum number of external components for proper operation.
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.
Decoupling Capacitors
Decoupling capacitors of 0.01F should be connected between VDD and GND, as close to the MK2731-01 as possible. For optimum device performance, the decoupling capacitors should be mounted on the component side of the PCB. Avoid the use of vias in the decoupling circuit.
Series Termination Resistor
When the PCB traces between the clock outputs and the loads are over 1 inch, series termination should be used. To series terminate a 50 trace (a commonly used trace impedance) place a 33 resistor in series with the clock line, as close to the clock output pin as possible. The nominal impedance of the clock output is 20.
Quartz Crystal
The MK2731-01 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 meeting ICS' recommended parameters must be used, and the layout guidelines discussed in the following section must be followed. See Application Note MAN05 for a full list of crystal parameters. The frequency of oscillation of a quartz crystal is determined by its "cut" and by the load capacitors connected to it. The MK2731-01 incorporates on-chip variable load capacitors that "pull" (change) the frequency of the crystal. The crystal specified for use with the MK2731-01 is designed to have zero frequency error when the total of on-chip + stray capacitance is 14 pF. The external crystal must be connected as close to the chip as possible and should be on the same side of the PCB as the MK2731-01. 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.
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MK2731-01 LOW COST VCXO
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2731-01. 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
-0.5 V to VDD+0.5 V 0 to +70C -65 to +150C 260C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature Power Supply Voltage (measured in respect to GND) Reference crystal parameters
Min.
0 +4.75
Typ.
Max.
+70 +5.25
Units
C V
Refer to page 3
DC Electrical Characteristics
VDD=3.3 V 5% , Ambient temperature 0 to +70C, unless stated otherwise
Parameter
Operating Voltage Output High Voltage Output Low Voltage Output High Voltage (CMOS Level) Input High Voltage (X1 only) Input High Voltage Input Low Voltage (X1 only) Input Low Voltage Operating Supply Current Short Circuit Current VIN, VCXO Control Voltage Frequency Synthesis Error Input Capacitance
Symbol
VDD VOH VOL VOH VIH VIH VIL VIL IDD IOS VIA
Conditions
IOH = -25 mA IOL = 25 mA IOH = -8 mA
Min.
4.75 2.4
Typ.
Max.
5.25 0.4
Units
V V V V
VDD-0.4 3.5 2.0 2.5 1.5 0.8 2.5
V V V V mA mA 3 0 V ppm pF
No load, S2:0 = 000 Each output 0 All clocks S0, S1, S2, OE
20 100
CIN
7
MDS 2731-01 E In te grated Circuit Systems
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AC Electrical Characteristics
VDD = 3.3 V 5%, Ambient Temperature 0 to +70 C, unless stated otherwise
Parameter
CLK1 and CLK2 Output Pullability Input Crystal Frequency Input Crystal Accuracy Output Clock Rise Time Output Clock Fall Time Output Clock Duty Cycle Maximum Absolute Jitter, short term Skew of CLK1 (with respect to CLK2)
Symbol
fP
Conditions
0V< VIN < 3 V, Note 1
Min.
+100
Typ.
Max. Units
ppm
10 or 13.5 +30 tOR tOF tD tJ 0.8 to 2.0V 2.0 to 0.8V Measured at 1.4V CL=15pF Measured at 1.4V 40 50 200 1 1.5 1.5 60
MHz ppm ns ns % ps ns
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
Thermal Characteristics
Parameter
Thermal Resistance Junction to Ambient
Symbol
JA JA JA JC
Conditions
Still air 1 m/s air flow 3 m/s air flow
Min.
Typ.
120 115 105 58
Max. Units
C/W C/W C/W C/W
Thermal Resistance Junction to Case
MDS 2731-01 E In te grated Circuit Systems
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Package Outline and Package Dimensions (16-pin 150 mil SOIC)
Package dimensions are kept current with JEDEC Publication No. 95
16
Millimeters Symbol Min Max
Inches Min Max
E INDEX AREA
H
12 D
A A1 B C D E e H h L
1.35 1.75 0.10 0.25 0.33 0.51 0.19 0.25 9.80 10.00 3.80 4.00 1.27 BASIC 5.80 6.20 0.25 0.50 0.40 1.27 0 8
.0532 .0688 .0040 .0098 .013 .020 .0075 .0098 .3859 .3937 .1497 .1574 0.050 BASIC .2284 .2440 .010 .020 .016 .050 0 8
A A1
h x 45 C
-Ce
B SEATING PLANE L
.10 (.004)
C
Ordering Information
Part / Order Number
MK2731-01G MK2731-01GTR
Marking
MK2731-01 MK2731-01
Shipping packaging
Tubes Tape and Reel
Package
16-pin SOIC 16-pin SOIC
Temperature
0 to +70 C 0 to +70 C
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems (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.
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