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PRELIMINARY INFORMATION
ICS3821
HIGH PERFORMANCE VCXO
Description
The ICS3821 is a low-jitter, high-performance 3.3 volt VCXO designed to replace expensive discrete VCXOs modules. The on-chip Voltage Controlled Crystal Oscillator accepts a 0 to 3.3 V input voltage to cause the output clocks to vary by 130 ppm. Using ICS' patented VCXO techniques, the device uses an inexpensive external pullable crystal in the range of 12 to 36 MHz to produce a VCXO output clock at that same frequency. ICS manufactures the largest variety of Set-Top Box and multimedia clock synthesizers for all applications. If more clock outputs are needed, see the MK3732 or MK377x family of parts. Consult ICS to eliminate VCXOs, crystals, and oscillators from your board. 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.
Features
* * * * * * * * *
Packaged in 8-pin SOIC Operational frequency range of 12 MHz to 36 MHz Uses an inexpensive external crystal On-chip patented VCXO with pull range of 130 ppm (minimum) VCXO tuning voltage of 0 to 3.3 V Operating voltage of 3.3 V 12 mA output drive capability at TTL levels Advanced, low-power, CMOS process Available in a lead-free package
Block Diagram
VDD VIN
X1 12 to 36 MHz Pullable Crystal
X2
Voltage Controlled Crystal Oscillator
12 to 36 MHz Clock (REFOUT)
GND
OE
MDS 3821 A 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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PRELIMINARY INFORMATION
ICS3821 HIGH PERFORMANCE VCXO
Pin Assignment
X1 DC VIN GND 1 2 3 4 8 7 6 5 X2 OE VDD REFOUT
8-Pin (150 mil) SOIC
Pin Descriptions
Pin Number
1 2 3 4 5 6 7 8
Pin Name
X1 DC VIN GND REFOUT VDD OE X2
Pin Type
Input -- Input Power Output Power Input Input
Pin Description
Crystal connection. Connect to the external pullable crystal. Do not connect anything to this pin. Voltage input to VCXO. Zero to 3.3 V signal which controls the VCXO frequency. Connect to ground. VCXO CMOS level clock output matches the nominal frequency of the crystal. Connect to +3.3 V (0.01f decoupling capacitor recommended). Output Enable. Active high input--1: Enable; 0: Hi-Z (Disable). Internal pull-up. Crystal connection. Connect to a pullable 12 to 36 MHz crystal.
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PRELIMINARY INFORMATION
ICS3821 HIGH PERFORMANCE VCXO
External Component Selection
The ICS3821 requires a minimum number of external components for proper operation.
Decoupling Capacitors
A decoupling capacitor of 0.01F should be connected between VDD and GND on pins 4 and 6 as close to the ICS3821 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.
Recommended Crystal Parameters: Initial Accuracy at 25C Temperature Stability Aging Load Capacitance Shunt Capacitance, C0 C0/C1 Ratio Equivalent Series Resistance
20 ppm 30 ppm 20 ppm 10 pf 7 pF Max 250 Max 35 Max
Series Termination Resistor
When the PCB trace between the clock output 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.
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 ICS3821. 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. See application note MAN05.
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.
Quartz Crystal
The ICS3821 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 ICS3821 incorporates on-chip variable load capacitors that pull (change) the frequency of the crystal. The crystal specified for use with the ICS3821 is designed to have zero frequency error when the total of on-chip + stray capacitance is 10 pF.
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PRELIMINARY INFORMATION
ICS3821 HIGH PERFORMANCE VCXO
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS3821. 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 5V
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
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PRELIMINARY INFORMATION
ICS3821 HIGH PERFORMANCE VCXO
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 No load
Min.
3.15 2.4
Typ.
Max.
3.45 0.4
Units
V V V V
VDD-0.4 6 50 0 3.3
mA mA V
AC Electrical Characteristics
VDD = 3.3 V 5%, Ambient Temperature 0 to +70 C, unless stated otherwise
Parameter
Output Frequency Crystal Pullability VCXO Gain Output Rise Time Output Fall Time Output Clock Duty Cycle Maximum Output Jitter, Peak-to-peak Phase Noise Relative to Carrier for 35.328 MHz
Symbol
FO FP tOR tOF tD tJ
Conditions
0V< VIN < 3.3 V, Note 1 VIN = VDD/2 + 1 V, Note 1 20% to 80%, CL=15 pF 80% to 20%, CL=15 pF Measured at 1.4 V, CL=15 pF CL=15 pF 1 kHz 10 kHz 100 kHz
Min.
12 + 130
Typ.
Max. Units
36 MHz ppm ppm/V 1.5 1.5 ns ns % ps dBc/Hz dBc/Hz dBc/Hz
115
40
50 60 -115 -140 -155
60 75
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
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PRELIMINARY INFORMATION
ICS3821 HIGH PERFORMANCE VCXO
Package Outline and Package Dimensions (8-pin SOIC)
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
.0532 .0688 .0040 .0098 .013 .020 .0075 .0098 .1890 .1968 .1497 .1574 0.050 BASIC .2284 .2440 .010 .020 .016 .050 0 8
*For reference only. Controlling dimensions in mm.
A A1 h x 45 C
-Ce
B SEATING PLANE L
.10 (.004)
C
Ordering Information
Part / Order Number
ICS3821M ICS3821MT ICS3821MLF ICS3821MLFT
Marking
ICS3821M ICS3821M ICS3821ML ICS3821ML
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
Parts that are ordered with a "LF" suffix to the part number are the Pb-Free configuration and are RoHS compliant. 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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