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ICS722 Dataheets PDF



Part Number ICS722
Manufacturers Integrated Circuit Systems
Logo Integrated Circuit Systems
Description VCXO
Datasheet ICS722 DatasheetICS722 Datasheet (PDF)

www.DataSheet4U.com ICS722 LOW COST 27 MHZ 3.3 VOLT VCXO Description The ICS722 is a low cost, 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 over ±100 ppm. Using ICS’ patented VCXO techniques, the device uses an inexpensive external pullable crystal in the range of 16.2 to 28 MHz to produce a VCXO output clock at that same .

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www.DataSheet4U.com ICS722 LOW COST 27 MHZ 3.3 VOLT VCXO Description The ICS722 is a low cost, 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 over ±100 ppm. Using ICS’ patented VCXO techniques, the device uses an inexpensive external pullable crystal in the range of 16.2 to 28 MHz to produce a VCXO output clock at that same frequency. 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. ICS manufactures the largest variety of Set-Top Box and multimedia clock synthesizers for all applications. Consult ICS to eliminate VCXOs, crystals, and oscillators from your board. Features • • • • • • • • Packaged in 8-pin SOIC Operational frequency range of 16.2 MHz to 28 MHz Uses an inexpensive external crystal On-chip patented VCXO with pull range of 230 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, sub-micron CMOS process DataShee Block Diagram DataSheet4U.com VDD VIN X1 16.2-28MHz Pullable Crystal X2 Voltage Controlled Crystal Oscillator 16.2-28MHz Clock (REFOUT) GND DataSheet4U.com MDS 722 A I n t e gra te d C i r c u i t S y s t e m s ● 1 525 Race Stre et, San Jo se, CA 9 5126 ● Revision 121404 te l (40 8) 2 97-12 01 ● w w w. i c st . c o m DataSheet4 U .com www.DataSheet4U.com ICS722 LOW COST 27 MHZ 3.3 VOLT VCXO Pin Assignment X1 VDD VIN GND 1 2 3 4 8 7 6 5 X2 DC DC REFOUT ICS722 8-Pin (150 mil) SOIC Pin Descriptions Pin Number 1 2 3 4 5 6 7 8 Pin Name XI VDD VIN GND REFOUT DC DC X2 Pin Type Input Power Input Power Output — — Input Pin Description Crystal connection. Connect to the external pullable crystal. Connect to +3.3 V (0.01µf decoupling capacitor recommended). DataSheet4U.com 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. Do not connect anything to this pin. Do not connect anything to this pin. Crystal connection. Connect to a external pullable crystal. et4U.com DataShee MDS 722 A 2 ● Revision 121404 ● DataSheet4U.com In te grated Circuit Systems 525 Ra ce Street, San Jose, CA 9512 6 tel (4 08) 297-1 201 ● w w w. i c s t . c o m DataSheet 4 U .com www.DataSheet4U.com ICS722 LOW COST 27 MHZ 3.3 VOLT VCXO External Component Selection The ICS722 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 ICS722 is designed to have zero frequency error when the total of on-chip + stray capacitance is 14 pF. Recommended Crystal Parameters: Initial Accuracy at 25°C Temperature Stability Aging Load Capacitance Shunt Capacitance, C0 C0/C1 Ratio Equivalent Series Resistance Decoupling Capacitors A decoupling capacitor of 0.01µF should be connected between VDD and GND on pins 2 and 4 as close to the ICS722 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 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. ±20 ppm ±30 ppm ±20 ppm 14 pf 7 pF Max 250 Max 35 Ω 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 ICS722. 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. et4U.com Quartz Crystal Crystal Tuning Load Capacitors The crystal traces should include pads for small fixed The ICS722 VCXO function consists of the external capacitors, one between X1 and ground, and another crystal and the integrated VCXO oscillator circuit. To DataSheet4U.com between X2 and ground. Stuffing of these capacitors assure the best system performance (frequency pull on the PCB is optional. The need for these capacitors is range) and reliability, a crystal device with the determined at system prototype evaluation, and is recommended parameters (shown below) must be influenced by the particular crystal used (manufacture used, and the layout guidelines discussed in the and frequency) and by PCB layout. The typical required following section shown .


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