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| PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer Description The ICS281 field programmable spread spectrum clock synthesizer generates up to three high-quality, high-frequency clock outputs including multiple reference clocks from a low-frequency crystal input. It is designed to replace crystals, crystal oscillators and stand alone spread spectrum devices in most electronic systems. Using ICS' VersaClockTM software to configure PLLs and outputs, the ICS281 contains a One-Time Programmable (OTP) ROM for field programmability. Programming features include input/output frequencies, spread spectrum amount and eight selectable configuration registers. Using Phase-Locked Loop (PLL) techniques, the device runs from a standard fundamental mode, inexpensive crystal, or clock. It can replace multiple crystals and oscillators, saving board space and cost. The ICS281 is also available in factory programmed custom versions for high-volume applications. Features * * * * * * * * * * * * * Packaged as 16-pin TSSOP Eight addressable registers Replaces multiple crystals and oscillators Output frequencies up to 200 MHz at 3.3 V Configurable Spread Spectrum Modulation Input crystal frequency of 5 to 27 MHz Input clock frequency of 3 to 166 MHz Up to three reference outputs Operating voltages of 3.3 V VDDO output control from 1.8 V to 3.3 V Controllable output drive levels Advanced, low-power CMOS process Available in Pb (lead) free packaging Block Diagram VDD PLL1 with Spread Spectrum Divide Logic and Output Enable Control CLK1 3 VDDO S2:S0 3 OTP ROM with PLL Values PLL2 CLK2 Crystal or clock input X1/ICLK Crystal Oscillator X2 External capacitors are required with a crystal input. PLL3 CLK3 GND 3 PDTS MDS 281 C Integrated Circuit Systems, Inc. 1 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer Pin Assignment GND S0 S1 VDD VDDO CLK1 GND X1/ICLK 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 S2 VDD PDTS GND CLK3 CLK2 VDD X2 16 pin (173 mil) TSSOP Pin Descriptions Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Pin Name GND S0 S1 VDD VDDO CLK1 GND X1 X2 VDD CLK2 CLK3 GND PDTS VDD S2 Pin Type Power Input Input Power Power Output Power XI XO Power Output Output Power Input Power Input Connect to ground. Pin Description Select pin 0. Internal pull-up resistor. Select pin 1. Internal pull-up resistor. Connect to +3.3 V. Power supply for outputs. Output clock 1. Weak internal pull-down when tri-state. Connect to ground. Crystal input. Connect this pin to a crystal or external input clock. Crystal Output. Connect this pin to a crystal. Float for clock input. Connect to +3.3 V. Output clock 2. Weak internal pull-down when tri-state. Output clock 3. Weak internal pull-down when tri-state. Connect to ground. Power-down tri-state. Powers down entire chip and tri-states clock outputs when low. Internal pull-up resistor. Connect to +3.3 V. Select pin 2. Internal pull-up resistor. MDS 281 C Integrated Circuit Systems, Inc. 2 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer External Components The ICS281 requires a minimum number of external components for proper operation. set within the range of M = 1 to 1024 and N = 1 to 32,895. The ICS281 also provides separate output divide values, from 2 through 63, to allow the two output clock banks to support widely differing frequency values from the same PLL. Each output frequency can be represented as: OutputFreq ---M N Series Termination Resistor Clock output traces over one inch should use series termination. 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. = REFFreq Output Drive Control The ICS281 has two output drive settings. For VDDO=VDD, low drive should be selected when outputs are less than 100 MHz. High drive should be selected when outputs are greater than 100 MHz. For VDDO<2.8 V, high drive should be selected for all output frequencies. (Consult the AC Electrical Characteristics for output rise and fall times for each drive option.) Decoupling Capacitors As with any high-performance mixed-signal IC, the ICS281 must be isolated from system power supply noise to perform optimally. Decoupling capacitors of 0.01F must be connected between each VDD and the PCB ground plane. For optimum device performance, the decoupling capacitor should be mounted on the component side of the PCB. Avoid the use of vias on the decoupling circuit. ICS VersaClock Software Crystal Load Capacitors The device crystal connections should include pads for small capacitors from X1 to ground and from X2 to ground. These capacitors are used to adjust the stray capacitance of the board to match the nominally required crystal load capacitance. Because load capacitance can only be increased in this trimming process, it is important to keep stray capacitance to a minimum by using very short PCB traces (and no vias) been the crystal and device. Crystal capacitors must be connected from each of the pins X1 and X2 to ground. The value (in pF) of these crystal caps should equal (CL -6 pF)*2. In this equation, CL= crystal load capacitance in pF. Example: For a crystal with a 16 pF load capacitance, each crystal capacitor would be 20 pF [(16-6) x 2] = 20. ICS applies years of PLL optimization experience into a user friendly software that accepts the user's target reference clock and output frequencies and generates the lowest jitter, lowest power configuration, with only a press of a button. The user does not need to have prior PLL experience or determine the optimal VCO frequency to support multiple output frequencies. VersaClock software quickly evaluates accessible VCO frequencies with available output divide values and provides an easy to understand, bar code rating for the target output frequencies. The user may evaluate output accuracy, performance trade-off scenarios in seconds. Spread Spectrum Modulation The ICS281 utilizes frequency modulation (FM) to distribute energy over a range of frequencies. By modulating the output clock frequencies, the device effectively lowers energy across a broader range of frequencies; thus, lowering a system's electromagnetic interference (EMI). The modulation rate is the time from transitioning from a minimum frequency to a maximum frequency and then back to the minimum. ICS281 Configuration Capabilities The architecture of the ICS281 allows the user to easily configure the device to a wide range of output frequencies, for a given input reference frequency. The frequency multiplier PLL provides a high degree of precision. The M/N values (the multiplier/divide values available to generate the target VCO frequency) can be MDS 281 C Integrated Circuit Systems, Inc. 3 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer Spread Spectrum Modulation can be applied as either "center spread" or "down spread". During center spread modulation, the deviation from the target frequency is equal in the positive and negative directions. The effective average frequency is equal to the target frequency. In applications where the clock is driving a component with a maximum frequency rating, down spread should be applied. In this case, the maximum frequency, including modulation, is the target frequency. The effective average frequency is less than the target frequency. The ICS281 operates in both center spread and down spread modes. For center spread, the frequency can be modulated between 0.125% to 2.0%. For down spread, the frequency can be modulated between -0.25% to -4.0%. Both output frequency banks will utilize identical spread spectrum percentage deviations and modulation rates, if a common VCO frequency can be identified. Spread Spectrum Modulation Rate The spread spectrum modulation frequency applied to the output clock frequency may occur at a variety of rates. For applications requiring the driving of "down-circuit" PLLs, Zero Delay Buffers, or those adhering to PCI standards, the spread spectrum modulation rate should be set to 30-33 kHz. For other applications, a 120 kHz modulation option is available. Absolute Maximum Ratings Stresses above the ratings listed below can cause permanent damage to the ICS281. 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. Parameter Supply Voltage, VDD Inputs Clock Outputs Storage Temperature Soldering Temperature Junction Temperature Condition Referenced to GND Referenced to GND Referenced to GND Max 10 seconds Min. -0.5 -0.5 -65 Typ. Max. 7 VDD+0.5 VDD+0.5 150 260 125 Units V V V C C C Recommended Operation Conditions Parameter Ambient Operating Temperature (ICS281PG/PGLF) Ambient Operating Temperature (ICS281PGI/PGILF) Power Supply Voltage (measured in respect to GND) Power Supply Ramp Time Min. 0 -40 +3.135 Typ. Max. +70 +85 Units C C V ms +3.3 +3.465 4 MDS 281 C Integrated Circuit Systems, Inc. 4 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer DC Electrical Characteristics Unless stated otherwise, VDD = 3.3 V 5%, Ambient Temperature -40 to +85C Parameter Operating Voltage VDDO Voltage Symbol VDD Conditions Min. 3.135 1.80 Typ. Max. 3.465 VDD Units V V mA Config. Dependent - See VersaClockTM Estimates Operating Supply Current Input High Voltage IDD Three 33.3333 MHz outs, VDD=VDDO=3.3V; PDTS = 1, no load, Note 1 PDTS = 0, no load, Note 1 S2:S0 S2:S0 VDD-0.5 0.4 ICLK ICLK IOH = -4 mA IOH = -8 mA (Low Drive); IOH = -12 mA (High Drive) IOL = 8 mA (Low Drive); IOL = 12 mA (High Drive) Low Drive High Drive Nom. Output Impedance Internal pull-up resistor Internal pull-down resistor Input Capacitance ZO RPUS RPD CIN S2:S0, PDTS CLK outputs Inputs 40 70 20 190 120 4 VDD-0.4 2.4 VDDO-0.4 0.4 VDD/2+1 VDD/2-1 VDD/2+1 0.4 20 mA 500 Input High Voltage Input Low Voltage Input High Voltage, PDTS Input Low Voltage, PDTS Input High Voltage Input Low Voltage Output High Voltage (CMOS High) Output High Voltage Output Low Voltage Short Circuit Current VIH VIL VIH VIL VIH VIL VOH VOH VOL IOS A V V V V V V V V V mA k k pF Note 1: Example with 25 MHz crystal input, three unloaded 33.3 MHz outputs and VDD = VDDO = 3.3 V. MDS 281 C Integrated Circuit Systems, Inc. 5 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer AC Electrical Characteristics Unless stated otherwise, VDD = 3.3 V 5%, Ambient Temperature -40 to +85 C Parameter Input Frequency Output Frequency Output Rise/Fall Time Output Rise/Fall Time Output Rise/Fall Time Symbol FIN Conditions Fundamental crystal Clock input VDDO=VDD 1.8 V 5 3 0.314 0.314 Typ. Max. Units 27 166 200 150 MHz MHz MHz MHz ns ns ns tOF tOF tOF 80% to 20%, high drive, Note 1 80% to 20%, low drive, Note 1 80% to 20%, high drive, 1.8 V Duty Cycle Output Frequency Synthesis Error Power-up Time 49-51 TBD 4 0.6 60 10 2 % ppm ms ms 4 7 ms One Sigma Clock Period Jitter Maximum Absolute Jitter Note 1: Measured with 15 pF load. tja Configuration Dependent Deviation from Mean. Configuration Dependent 50 +200 ps ps Note 2: Duty Cycle is configuration dependent. Most configurations are min 45% / max 55%. 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. 78 70 68 37 Max. Units C/W C/W C/W C/W Thermal Resistance Junction to Case MDS 281 C Integrated Circuit Systems, Inc. 6 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer Marking Diagrams 16 9 Marking Diagrams (Pb free) 16 9 281PG ###### YYWW 1 16 8 9 1 16 281PGL ###### YYWW 8 9 281PGI ###### YYWW 1 8 1 281PGIL ###### YYWW 8 Notes: 1. ###### is the lot number. 2. YYWW is the last two digits of the year and week that the part was assembled. 3. "I" denotes industrial temperature range (if applicable). 4. "L" denotes Pb (lead) free package. 5. Bottom marking: country of origin. MDS 281 C Integrated Circuit Systems, Inc. 7 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com PRELIMINARY INFORMATION ICS281 Triple PLL Field Prog. Spread Spectrum Clock Synthesizer Package Outline and Package Dimensions (16-pin TSSOP, 173 Mil. Body) Package dimensions are kept current with JEDEC Publication No. 95 24 Millimeters Symbol E1 E Inches Min Max Min Max INDEX AREA 12 D A A1 A2 b C D E E1 e L -- 1.20 0.05 0.15 0.80 1.05 0.19 0.30 0.09 0.20 4.90 5.10 6.40 BASIC 4.30 4.50 0.65 Basic 0.45 0.75 0 8 -- .047 0.002 0.006 0.032 0.041 0.007 0.012 0.0035 0.008 0.193 0.201 0.252 BASIC 0.169 0.177 0.0256 Basic .018 .030 0 8 A2 A1 A c - Ce b SEATING PLANE .10 (.004) C L Ordering Information Part / Order Number ICS281PG ICS281PGI ICS281PGLF ICS281PGILF See page 7 Marking Shipping Packaging Tubes Tubes Tubes Tubes Package 16-pin TSSOP 16-pin TSSOP 16-pin TSSOP 16-pin TSSOP Temperature 0 to +70C -40 to +85C 0 to +70C -40 to +85C 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. VersaClockTM is a trademark of Integrated Circuit Systems, Inc. All rights reserved. MDS 281 C Integrated Circuit Systems, Inc. 8 525 Race Street, San Jose, CA 95126 Revision 062205 tel (408) 297-1201 www.icst.com |
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