MK3727STR [ICSI]
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO; LOW COST 24 - 36 MHZ 3.3伏VCXO
| 型号： | MK3727STR |
| 厂家： | 
INTEGRATED CIRCUIT SOLUTION INC |
| 描述： | LOW COST 24 - 36 MHZ 3.3 VOLT VCXO |
| 文件： | 总6页 (文件大小：78K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MK3727
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO
VIN is a high impedance input, it can be driven directly
from an PWM RC integrator circuit. Frequency output
Description
increases with VIN voltage input. The usable range of
VIN is 0 to 3V.
The MK3727 series of devices include the original
MK3727S, MK3727A, and the new MK3727C and
MK3727D. The MK3727D and MK3727C are drop-in
replacements for the MK3727S and MK3727A devices.
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.
Features
• MK3727D and MK3727C are drop-in upgrades to the
earlier MK3727S and MK3727A devices
• MK3727D and MK3727C offer 24-36 MHz output
frequency range (output frequency = 2x crystal
frequency) and improved power supply noise
rejection
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
• 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
applications within end products such as ADSL
modems, set-top box receivers, and telecom systems.
• Ideal for set-top box applications using 13.5 MHz
external pullable crystal to generate lock 27 MHz
clock transport video clock
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, similar to the earlier
MK3727A. 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.
• 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 is Recommended for New Designs.
The frequency of the on-chip VCXO is adjusted by an
external control voltage input into pin VIN. Because
Block Diagram
VIN
X1
Voltage
12-18 MHz
PLL
Controlled
24-36 MHz
Pullable
Frequency
Doubler
Crystal
(2x Crystal Frequency)
Crystal
X2
Oscillator
MDS 3727 E
1
Revision 052901
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com
MK3727
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO
Pin Assignment
X 1
V D D
V I N
8
7
6
5
1
2
3
4
X 2
G N D
N C
G N D
C L K
M K 3 7 2 7 S
M K 3 7 2 7 A
M K 3 7 2 7 C
M K 3 7 2 7 D
8 P i n ( 1 5 0 m i l ) S O I C
Pin Descriptions
Pin
Pin
Pin
Pin Description
Number
Name
Type
1
2
3
XI
Input
Crystal connection -- Connect to the external pullable crystal.
VDD
VIN
Power Connect to +3.3 V (0.01uf decoupling capacitor recommended)
Input
Voltage input to VCXO -- 0 to 3.3 V analog input which controls the
oscillation frequency of the VCXO.
4
5
6
7
8
GND
CLK
NC
Power Connect to ground
Output Clock output
--
No internal connection (may connect to ground or VDD)
GND
X2
Power Connect to ground
Input
Crystal connection -- Connect to the external pullable crystal.
MDS 3727 E
2
Revision 052901
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com
MK3727
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO
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 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.
External Component Selection
The MK3727 requires a minimum number of external
components for proper operation.
Decoupling Capacitor
A decoupling capacitor of 0.01µF 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.
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.
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 50Ω trace (a
commonly used trace impedance) place a 33Ω resistor
in series with the clock line, as close to the clock output
pin as possible. The nominal impedance of the clock
output is 20Ω.
To determine the need for and value of the crystal
adjustment capacitors, you will need a PC board of
your final layout, a frequency counter capable of about
1 ppm resolution and accuracy, two power supplies,
and some samples of the crystals which you plan to
use in production, along with measured initial accuracy
for each crystal at the specified crystal load
capacitance, CL.
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.
To determine the value of the crystal capacitors:
1. Connect VDD of the MK3727 to 3.3V. Connect pin 3
of the MK3727 to the second power supply. Adjust the
voltage on pin 3 to 0V. Measure and record the
frequency of the CLK output.
2. Adjust the voltage on pin 3 to 3.3V. Measure and
record the frequency of the same output.
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
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
14pF.
To calculate the centering error:
(f3.0V – ftarget) + (f0V – ftarget
)
Error = 106x ------------------------------------------------------------------------------ – errorxtal
ft arget
Recommended Crystal Parameters:
Where:
Initial Accuracy at 25°C
Temperature Stability
Aging
Load Capacitance
Shunt Capacitance, C0
C0/C1 Ratio
±20 ppm
±30 ppm
±20 ppm
14 pf
7 pF Max
250 Max
35 Ω Max
ftarget = nominal crystal frequency
errorxtal =actual initial accuracy (in ppm) of the crystal
being measured
If the centering error is less than ±25 ppm, no
adjustment is needed. If the centering error is more
than 25ppm negative, the PC board has excessive
stray capacitance and a new PCB layout should be
Equivalent Series Resistance
MDS 3727 E
3
Revision 052901
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com
MK3727
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO
considered to reduce stray capacitance. (Alternately,
the crystal may be re-specified to a higher load
capacitance. Contact ICS MicroClock for details.) If the
centering error is more than 25ppm positive, add
identical fixed centering capacitors from each crystal
pin to ground. The value for each of these caps (in pF)
is given by:
External Capacitor =
2 x (centering error)/(trim sensitivity)
Trim sensitivity is a parameter which can be supplied
by your crystal vendor. If you do not know the value,
assume it is 30 ppm/pF. After any changes, repeat the
measurement to verify that the remaining error is
acceptably low (typically less than ±25ppm).
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
Rating
Supply Voltage, VDD
All Inputs and Outputs
7V
-0.5V to VDD+0.5V
0 to +70°C
Ambient Operating Temperature
Storage Temperature
-65 to +150°C
260°C
Soldering Temperature
Recommended Operation Conditions
Parameter
Min.
Typ.
Max.
+70
Units
°C
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Reference crystal parameters
0
–
+3.15
+3.45
V
Refer to page 3
MDS 3727 E
4
Revision 052901
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com
MK3727
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO
DC Electrical Characteristics
VDD=3.3V ±5% , Ambient temperature 0 to +70°C, unless stated otherwise
Parameter
Operating Voltage
Symbol
VDD
VOH
Conditions
Min.
3.15
2.4
Typ.
Max.
Units
3.45
V
V
V
V
Output High Voltage
Output Low Voltage
IOH = -12 mA
IOL = 12 mA
IOH = -4 mA
VOL
0.4
Output High Voltage (CMOS
Level)
VOH
VDD-0.4
Operating Supply Current
IDD
Output = 27 MHz,
no load
10
mA
Short Circuit Current
IOS
±50
mA
V
VIN, VCXO Control Voltage
VIA
0
3.3
AC Electrical Characteristics
VDD = 3.3V ±5%, Ambient Temperature 0 to +70° C, unless stated otherwise
Parameter
Symbol
Conditions
Min. Typ. Max. Units
Output Frequency
MK3727D and
MK3727C
FO
FO
VCXO Crystal frequency =
1/2 Output
24
36
MHz
MHz
MK3727A and
MK3727S
VCXO Crystal frequency =
13.5 MHz
27
Crystal Pullability
MK3727D and
MK3727C
FP
FP
0V< VIN < 3.3V, Note 1
0V< VIN < 3.3V, Note 1
+ 115
+ 100
ppm
ppm
MK3727A and
MK3727S
VCXO Gain
MK3727D
VIN = VDD/2 + 1V, Note 1
VIN = VDD/2 + 1V, Note 1
VIN = VDD/2 + 1V, Note 1
VIN = VDD/2 + 1V, Note 1
0.8 to 2.0V, CL=15pF
2.0 to 0.8V, CL=15pF
Measured at 1.4V, CL=15pF
CL=15pF
120
150
170
100
ppm/V
ppm/V
ppm/V
ppm/V
ns
MK3727C
MK3727A
MK3727S
Output Rise Time
Output Fall Time
Output Clock Duty Cycle
tOR
tOF
tD
1.5
1.5
60
ns
40
50
%
Maximum Output Jitter,
short term
tJ
100
ps
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
MDS 3727 E
5
Revision 052901
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com
MK3727
LOW COST 24 - 36 MHZ 3.3 VOLT VCXO
Package Outline and Package Dimensions (8 pin SOIC, 150 Mil. Narrow Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters
Inches
Min Max
Symbol
Min
Max
1.75
0.25
0.51
0.25
5.00
4.00
A
A1
B
C
D
E
e
1.35
1.10
0.33
0.19
4.80
3.80
0.0532 0.0688
0.0040 0.0098
0.013
0.0075 0.0098
.1890 .1968
0.020
Index
Area
0.1497 0.1574
0.050 Basic
E H
1.27 Basic
H
h
L
5.80
0.25
0.40
0°
6.20
0.50
1.27
8°
0.2284 0.2440
0.010
0.016
0°
0.020
0.050
8°
a
Pin 1
D
h x 450
A
Q
c
e
b
Ordering Information
Part / Order Number
(Note 1)
Marking
Shipping
packaging
Package
Temperature
MK3727D
MK3727D
MK3727D
MK3727C
MK3727C
MK3727A
MK3727A
MK3727S
MK3727S
Tubes
8 pin SOIC
8 pin SOIC
8 pin SOIC
8 pin SOIC
8 pin SOIC
8 pin SOIC
8 pin SOIC
8 pin SOIC
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
MK3727DTR
MK3727C
Tape and Reel
Tubes
MK3727CTR
MK3727A
Tape and Reel
Tubes
MK3727ATR
MK3727S
Tape and Reel
Tubes
MK3727STR
Tape and Reel
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.
MDS 3727 E
6
Revision 052901
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com
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