ICS3727XP [ICSI]
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO; LOW COST 24〜36 MHZ 3.3伏VCXO
| 型号： | ICS3727XP |
| 厂家： | 
INTEGRATED CIRCUIT SOLUTION INC |
| 描述： | LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO |
| 文件： | 总7页 (文件大小：129K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO
Description
Features
The ICS3727XP combines the functions of a VCXO
(Voltage Controlled Crystal Oscillator) and PLL
(Phase-Locked Loop) frequency doubler onto a single
chip. It is designed primarily for data and clock recovery
applications within end products such as set-top box
receivers.
• ICS3727XP offers 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 DV CODEC applications using 27 MHz
external pullable crystal with extended pull range to
generate locked 27 MHz clock transport video clock
The ICS3727XP exhibits a moderate VCXO gain of 200
ppm/V typical, when used with a high quality external
pullable quartz crystal.
• On-chip VCXO with guaranteed pull range of 200
ppm minimum
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 3.3 V.
• VCXO input tuning voltage 0 to 3.3 V
• Packaged in 8-pin SOIC (150 mil wide)
Block Diagram
VIN
X1
Voltage
12-18 MHz
PLL
Frequency
Doubler
Controlled
24-36 MHz
(2x Crystal Frequency)
Pullable
Crystal
Crystal
Oscillator
X2
MDS 3727XP A
1
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO
Pin Assignment
X1
8
7
6
5
1
2
3
4
X2
VDD
VIN
GND
NC
GND
CLK
ICS3727XP
8-pin (150 mil) SOIC
Pin Descriptions
Pin
Number
Pin
Name
Pin
Type
Pin Description
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 3727XP A
2
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 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 ICS3727XP. 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 ICS3727XP 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 ICS3727XP 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 ICS3727XP to 3.3 V. Connect
pin 3 of the ICS3727XP 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 3.3 V. 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 ICS3727XP incorporates on-chip
variable load capacitors that “pull” (change) the
frequency of the crystal. The crystal specified for use
with the ICS3727XP is designed to have zero
frequency error when the total of on-chip + stray
capacitance is 14 pF.
To calculate the centering error:
(f3.0V – ftarget) + (f0V – ftarget
)
Error = 106x
– errorxtal
------------------------------------------------------------------------------
ftarget
Recommended Crystal Parameters:
Where:
= nominal crystal frequency
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
35Ω Max
f
target
error
=actual initial accuracy (in ppm) of the crystal
xtal
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 3727XP A
3
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO
considered to reduce stray capacitance. (Alternately,
the crystal may be re-specified to a higher load
External Capacitor = 2 x (centering error)/(trim
sensitivity)
capacitance. Contact ICS for details.) If the centering
error is more than 25 ppm positive, add identical fixed
centering capacitors from each crystal pin to ground.
The value for each of these caps (in pF) is given by:
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 25 ppm).
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS3727XP. 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
7 V
-0.5 V to VDD+0.5 V
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 3727XP A
4
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO
DC Electrical Characteristics
VDD=3.3 V ±±% , Ambient temperature 0 to +70°C, unless stated otherwise
Parameter
Symbol
Conditions
Min.
3.15
2.4
Typ.
Max.
Units
Operating Voltage
VDD
3.45
V
V
V
V
Output High Voltage
Output Low Voltage
V
I
I
I
= -12 mA
= 12 mA
= -4 mA
OH
OH
OL
OH
V
0.4
OL
Output High Voltage (CMOS
Level)
V
VDD-0.4
OH
Operating Supply Current
IDD
Output = 27 MHz,
no load
10
50
mA
Short Circuit Current
I
mA
V
OS
VIN, VCXO Control Voltage
V
0
3.3
IA
AC Electrical Characteristics
VDD = 3.3 V ±±%, Ambient Temperature 0 to +70° C, unless stated otherwise
Parameter
Symbol
Conditions
Min. Typ. Max. Units
Output Frequency
F
VCXO Crystal frequency =
1/2 Output
24
36
MHz
O
Crystal Pullability
VCXO Gain
F
0V< VIN < 3.3 V, Note 1
+ 200
ppm
ppm/V
ns
P
VIN = VDD/2 + 1 V, Note 1
200
Output Rise Time
Output Fall Time
Output Clock Duty Cycle
t
0.8 to 2.0 V, C =15 pF
1.5
1.5
60
OR
L
t
2.0 to 0.8 V, C =15 pF
ns
OF
L
t
Measured at 1.4 V, C =15 pF
40
50
%
D
L
Maximum Output Jitter,
short term
t
C =15 pF
100
ps
J
L
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
MDS 3727XP A
5
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 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
0.0532 0.0688
0.0040 0.0098
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
0.013
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 4±0
A
Q
c
e
b
Ordering Information
Part / Order Number
ICS3727XPM
Marking
3727XPM
3727XPM
Shipping Packaging
Tubes
Package
8-pin SOIC
8-pin SOIC
Temperature
0 to +70° C
0 to +70° C
ICS3727XPMT
Tape and Reel
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 3727XP A
6
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
PRELIMINARY INFORMATION
ICS3727XP
LOW COST 24 TO 36 MHZ 3.3 VOLT VCXO
Revision History
Rev. Originator
P.Griffith
Date
Description of Change
A
10/20/04 New device/datasheet.
MDS 3727XP A
7
Revision 102004
Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
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