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MK2727
LOW COST 27 MHZ VCXO
The MK2727 is ICS's lowest cost, low-jitter, high-performance VCXO and PLL clock synthesizer designed to replace expensive 27MHz VCXOs. 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 external 13.5 MHz pullable crystal input to produce a 27 MHz output clock. ICS manufactures the largest variety of Set-Top Box and multimedia clock synthesizers for all applications. If more clock outputs are needed, see the MK2731 or MK277x family of parts. Consult ICS to eliminate VCXOs, crystals and oscillators from your board.
Features
* Packaged in 8-pin narrow SOIC * Uses an inexpensive 13.500 MHz external crystal * On-chip VCXO with pull range of 200 ppm
(minimum)
* * * *
VCXO input tuning voltage 0 to 3.3 V 25 mA output drive capability at TTL levels Advanced, low-power, sub-micron CMOS process 5 V operating voltage
Block Diagram
VIN
13.5 MHz Pullable Crystal
X1
X2
Voltage Controlled Crystal Oscillator
PLL/Clock Synthesis Circuitry
27 MHz
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Pin Assignment
X1 VDD VIN GND
1 2 3 4 8 7 6 5 X2 GND VDD CLK
8-Pin (150 mil) SOIC
Pin Descriptions
Pin Number
1 2 3 4 5 6 7 8
Pin Name
XI VDD VIN GND CLK VDD GND X2
Pin Type
Input Power Input Power Output Power Power Input Connect to +5 V.
Pin Description
Crystal connection. Connect to a pullable 13.5 MHz crystal. Voltage input to VCXO. Zero to 3 V analog input which controls the frequency of the VCXO. Connect to ground. 27 MHz clock output. Connect to +5 V. Connect to ground. Crystal connection. Connect to a pullable 13.5 MHz crystal.
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External Component Selection
The MK2727 requires a minimum number of external components for proper operation.
variable load capacitors that "pull" (change) the frequency of the crystal. The crystal specified for use with the MK2727 is designed to have zero frequency error when the total of on-chip + stray capacitance is 14 pF. Recommended Crystal Parameters: Initial Accuracy at 25C Temperature Stability Aging Load Capacitance Shunt Capacitance, C0 C0/C1 Ratio Equivalent Series Resistance
Decoupling Capacitor
A decoupling capacitor of 0.01F 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.
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 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.
20 ppm 30 ppm 20 ppm 14 pf 7 pF Max 250 Max 35 Max
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 MK2727. There should be no vias between the crystal pins and the X1 and X2 device pins. There should be no signal traces underneath or close to the crystal.
Quartz Crystal
The MK2727 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 MK2727 incorporates on-chip
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. 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.
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Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2727. 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.
5.0
Max.
+70 +5.25
Units
C V
Refer to page 3
DC Electrical Characteristics
VDD=5 V 5% , Ambient temperature 0 to +70C, 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 VOH VOL VOH IDD IOS VIA
Conditions
IOH = -25 mA IOL = 25 mA IOH = -8 mA No load
Min.
4.75 2.4
Typ.
Max.
5.25 0.4
Units
V V V V
VDD-0.4 20 100 0 3
mA mA V
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AC Electrical Characteristics
VDD = 5 V 5%, Ambient Temperature 0 to +70 C, unless stated otherwise
Parameter
Input Crystal Frequncy Input Crystal Accuracy Output Clock Rise Time Output Clock Fall Time Outpu Clock Duty Cycle Maximum Absolute Jitter, short term 27 MHz Output Pullability
Symbol
Conditions
Min.
Typ.
13.500
Max.
+30
Units
MHz ppm ns ns % ps ppm
tOR tOF tD tJ
0.8 to 2.0 V 2.0 to 0.8 V Measured at 1.4 V 40 50 200 0V < VIN < 3 V, Note 1 +100
1.5 1.5 60
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.
150 140 120 40
Max. Units
C/W C/W C/W C/W
Thermal Resistance Junction to Case
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Package Outline and Package Dimensions (8-pin SOIC, 150 Mil. Narrow Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters Symbol Min Max Inches Min Max
8
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 4.80 5.00 3.80 4.00 1.27 BASIC 5.80 6.20 0.25 0.50 0.40 1.27 0 8
h x 45
.0532 .0688 .0040 .0098 .013 .020 .0075 .0098 .1890 .1968 .1497 .1574 0.050 BASIC .2284 .2440 .010 .020 .016 .050 0 8
A A1
C
-Ce
B SEATING PLANE L
.10 (.004)
C
Ordering Information
Part / Order Number
MK2727S MK2727STR MK2727SLF MK2727SLFTR
Marking
MK2727S MK2727S 2727SL 2727SL
Shipping Packaging
Tubes Tape and Reel Tubes Tape and Reel
Package
8-pin SOIC 8-pin SOIC 8-pin SOIC 8-pin SOIC
Temperature
0 to +70 C 0 to +70 C 0 to +70 C 0 to +70 C
"LF" denotes Pb (lead) free package.
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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