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MK3727
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO
Description
The MK3727 series of devices include the original MK3727S, and the new MK3727C and MK3727D. The MK3727D and MK3727C are drop-in replacements for the MK3727S device. Compared to these earlier devices, the MK3727D and MK3727C offer a wider operating frequency range and improved power supply noise rejection. The MK3727D is recommended for new designs. The MK3727 series combines the functions of a VCXO (Voltage Controlled Crystal Oscillator) and PLL (Phase Locked Loop) frequency doubler onto a single chip. Used in conjunction with an external pullable quartz crystal, this monolithic integrated circuit replaces more costly hybrid (canned) VCXO devices. The MK3727 is designed primarily for data and clock recovery applications within end products such as ADSL modems, set-top box receivers, and telecom systems. The MK3727D is recommended for new designs. The MK3727D exhibits a moderate VCXO gain of 120ppm/V typical, when used with a high quality external pullable quartz crystal. The MK3727C offers a higher VCXO gain of 150ppm/V. The higher intrinsic VCXO gain of the MK3727C may help compensate for the reduced pullability of a low quality crystal used in some applications. However, higher VCXO gain may also increase clock output phase noise. The frequency of the on-chip VCXO is adjusted by an external control voltage input into pin VIN. Because VIN is a high impedance input, it can be driven directly from an PWM RC integrator circuit. Frequency output increases with VIN voltage input. The usable range of VIN is 0 to 3 V.
Features
* MK3727D and MK3727C are drop-in upgrades to the
earlier MK3727S device
* MK3727D and MK3727C offer 24 to 36 MHz output
frequency range (output frequency = 2x crystal frequency) and improved power supply noise rejection
* Uses an inexpensive 12 to 18 MHz external crystal * Ideal for ADSL applications using 17.664 MHz
external pullable crystal to generate locked 35.328 MHz clock physical layer clock
* Ideal for set-top box applications using 13.5 MHz
external pullable crystal to generate lock 27 MHz clock transport video clock
* On-chip VCXO with guaranteed pull range of 115
ppm minimum (MK3727D)
* * * *
VCXO input tuning voltage 0 to 3.3 V Packaged in 8-pin SOIC (150 mil wide) MK3727D available in Pb-free packaging MK3727D is recommended for new designs.
Block Diagram
V IN
12 to 1 8 M H z P ullab le C rystal
X1
X2
V o lta g e C o n tro lled C ry sta l O s cilla to r
PLL F re q u e n c y D o u b ler
24 to 36 M H z (2x C rystal F re q ue ncy)
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Pin Assignment
X1 VDD VI N GND
1 2 3 4 8 7 6 5 X2 GND NC CLK
MK3 7 2 7 C MK3 7 2 7 D 8 - Pi n ( 1 5 0 mi l ) SOI C
X1 VDD VIN GND
1 2 3 4
8 7 6 5
X2 GND VDD CLK
MK3727S 8- Pi n ( 150 mi l ) SOI C
Pin Descriptions
Pin Number
1 2 3 4 5 6 (3727C/D) 6 (3727S) 7 8
Pin Name
XI VDD VIN GND CLK NC VDD GND X2
Pin Type
Input Power Input Power Output -- Power Power Input
Pin Description
Crystal connection -- Connect to the external pullable crystal. Connect to +3.3 V (0.01uf decoupling capacitor recommended) Voltage input to VCXO -- 0 to 3.3 V analog input which controls the oscillation frequency of the VCXO. Connect to ground Clock output No internal connection (may connect to ground or VDD) Connect to VDD Connect to ground Crystal connection -- Connect to the external pullable crystal.
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External Component Selection
The MK3727 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 MK3727 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 & 7), 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 MK3727. 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 MK3727 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 MK3727 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 MK3727. 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 +3.15
Typ.
Max.
+70 +3.45
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) Operating Supply Current Short Circuit Current VIN, VCXO Control Voltage
Symbol
VDD VOH VOL VOH IDD IOS VIA
Conditions
IOH = -12 mA IOL = 12 mA IOH = -4 mA Output = 27 MHz, no load
Min.
3.15 2.4
Typ.
Max.
3.45 0.4
Units
V V V V
VDD-0.4 10 50 0 3.3
mA mA V
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AC Electrical Characteristics
VDD = 3.3 V 5%, Ambient Temperature 0 to +70 C, unless stated otherwise
Parameter
Output Frequency MK3727D and MK3727C MK3727S Crystal Pullability MK3727D and MK3727C MK3727S VCXO Gain MK3727D MK3727C MK3727S Output Rise Time Output Fall Time Output Clock Duty Cycle Maximum Output Jitter, short term
Symbol
FO FO
Conditions
VCXO Crystal frequency = 1/2 Output VCXO Crystal frequency = 13.5 MHz 0V< VIN < 3.3 V, Note 1 0V< VIN < 3.3 V, Note 1 VIN = VDD/2 + 1 V, Note 1 VIN = VDD/2 + 1 V, Note 1 VIN = VDD/2 + 1 V, Note 1
Min.
24
Typ.
Max. Units
36 MHz MHz
27
FP FP
+ 115 + 100 120 150 100 1.5 1.5 45 50 100 55
ppm ppm ppm/V ppm/V ppm/V ns ns % ps
tOR tOF tD tJ
0.8 to 2.0 V, CL=15 pF 2.0 to 0.8 V, CL=15 pF Measured at 1.4 V, CL=15 pF CL=15 pF
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
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Ordering Information
Part / Order Number (Note 1)
MK3727D MK3727DTR MK3727DLF MK3727DLFTR MK3727C MK3727CTR MK3727S MK3727STR MK3727SLF MK3727SLFTR MK3727D-DPK
Marking
MK3727D MK3727D 3727DLF 3727DLF MK3727C MK3727C MK3727S MK3727S 3727SLF 3727SLF --
Shipping Packaging
Tubes Tape and Reel Tubes Tape and Reel Tubes Tape and Reel Tubes Tape and Reel Tubes Tape and Reel Tested die in waffle pack
Package
8-pin SOIC 8-pin SOIC 8-pin SOIC 8-pin SOIC 8-pin SOIC 8-pin SOIC 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 0 to +70 C 0 to +70 C 0 to +70 C 0 to +70 C 0 to +70 C 0 to +70 C 0 to +70 C
"LF" denotes Pb (lead) free package.
Note 1: MK3727D is recommended for new designs.
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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