Manuals / Silicon Laboratories / Computer Equipment / Clock

Silicon Laboratories SI5324, SI5369 Free Run Reference Frequency Constraints,  While in Free Run

Models: SI5326 SI5319 SI5369 SI5324 SI5367 SI5322 SI5316 SI5327 SI5366 SI5374 SI5325 SI5323 SI5368 SI5365 SI5375

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Si53xx-RM

7.5.3. Free Run Reference Frequency Constraints

XA/XB Frequency Min		XA/XB Frequency Max			Xtal

109 MHz				125.5 MHz	3rd overtone

37 MHz				41 MHz	Fundamental

	CKIN			XA-XB
	---N31-----------		=	----N32-------------= f3

CKOUT

---------------------≠ Integer

XA-XB

All crystals and external oscillators must lie within these two bands

Not every crystal will work; they should be tested An external oscillator can be used at all four bands

The frequency at the phase detector (f3) must be the same for both CKIN1 and XA/XB or else switching cannot be hitless

To avoid spurs, avoid outputs that are an integer (or near integer) of the XA/XB frequency.

7.5.4.Free Run Reference Frequency Constraints

 While in Free Run:

CKOUT frequency tracks the reference frequency.

 For very low drift, a TCXO or OCXO reference is necessary.

 CKOUT Jitter:

XA/XB to CKOUT jitter transfer function is roughly one-to-one.

For very low jitter, either use a high quality crystal or external oscillator.  3rd overtone crystals have lower close-in phase noise.

In general, higher XA/XB frequency > lower jitter.

 XA/XB frequency accuracy:

For hitless switching, to meet all published specifications, the XA/XB frequency divided by N32 should match the CLKIN frequency divided by N31. If they do not match, the clock switch will still be well-behaved.

Other than the above, the absolute accuracy of the XA/XB frequency is not important.

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Silicon Laboratories SI5324, SI5369, SI5365, SI5366, SI5367 Free Run Reference Frequency Constraints,  While in Free Run

Contents

ANY-FREQUENCY Precision Clocks Si53xx-RM Table of Contents Output Clock Drivers Si5375 Free Run Mode High-Speed I/O Si53xx-RM List of Figures Differential Output Example Requiring Attenuation 108 Si53xx-RM List of Tables Si53xx-RM Any-Frequency Precision Clock Product Family Overview Si53xx-RM Product Selection Guide PLL Precision Clock Multipliers Wideband Product Selection Guide Si5322/25/65/67Device Narrowband vs. Wideband Overview Any-Frequency Clock Family Members Si5316 Si5319 Dspll Si5322 Low Jitter Clock Multiplier Block Diagram Si5322 Si5323 Jitter Attenuating Clock Multiplier Block Diagram Si5323 Si5324 Clock Multiplier and Jitter Attenuator Block Diagram Si5324 Si5325 Low Jitter Clock Multiplier Block Diagram Si5325 Si5326 Clock Multiplier and Jitter Attenuator Block Diagram Si5326 Si5327 Clock Multiplier and Jitter Attenuator Block Diagram Si5327 Si5365 Low Jitter Clock Multiplier Block Diagram Si5365 Si5366 Jitter Attenuating Clock Multiplier Block Diagram 10. Si5366 Si5367 Clock Multiplier Block Diagram 11. Si5367 Si5368 Clock Multiplier and Jitter Attenuator Block Diagram 12. Si5368 13. Si5369 14. Si5374/75 Compared to Si5324/19 Si5374 Functional Block Diagram 15. Si5374 Si5375 Functional Block Diagram 16. Si5375 Recommended Operating Conditions1 Device SpecificationsParameter Symbol Test Condition Min Typ Max Unit DC Characteristics CKINn Input Pins Lvpecl 100 Ω Level Lvcmos Input Pins Level Input Pins Lvcmos Output Pins RST SPI Specifications Si5324, Si5325, Si5367, and Si5368 Parameter Symbol Test Conditions Min Typ Max Unit Differential Reference Clock Input Pins XA/XB SDO Frame Synchronization Timing AC Characteristics-All Devices Min Typ Max Units Lvcmos Pins Device Skew PLL Performance Ckopn Jitter Generation Si5316, Si5324, Si5366, Si5368 Jitter Generation Si5322, Si5325, Si5365, Si5367 Thermal Characteristics Parameter Symbol Test Condition Devices Value Unit Any-Frequency Precision Clock Dspll Block Diagram Dspll All Devices Clock Multiplication Clock Multiplication Circuit Jitter Transfer PLL PerformanceJitter Generation Jitter Tolerance Mask/Template Jitter Tolerance Pin Control Parts Si5316, Si5322, Si5323, Si5365, Si5366 Si5316, Si5322, Si5323, Si5365 and Si5366 Key FeaturesFrequency Settings Clock Multiplication Si5316, Si5322, Si5323, Si5365, Si5366 CKnDIV N3n Input Divider Input Divider SettingsSi5316 Bandwidth Values FRQSEL10 Nominal Frequency Values MHz BW10 Fsout MHz Sonet Clock Multiplication Settings FRQTBL=LClock Multiplication Si5322, Si5323, Si5365, Si5366 Ckconf = FIN MHz Mult Factor All Devices Si5366 Only FOUT MHz Mllm Hlll Hhlh MHz Mult Factor OUT* MHz Datacom Clock Multiplication Settings Frqtbl = M, Ckconf =Setting 125 10/8 x 66/64 161.13 173.37 X 64/66 x 237/255 125 Hhhl Sonet to Datacom Clock Multiplication Settings FIN MHz Mult Factor FOUT* MHz 62.500 125 155.520 15625/15552 156.25 Lock Detect Si5322 and Si5365 Clock Output Divider Control DIV34CKOUT3 and CKOUT4 Si5365 and Si5366 Input-to-Output Skew Si5322 and Si5365 PLL Self-Calibration Si5316, Si5322, and Si5323 Pins and Reset Si5365 and Si5366 Pins and Reset Pin Control Input Clock Control Manual Input Clock Selection Si5365, Si5366, Autosel = L Input Clock Priority for Auto Switching Si5322, Si5323 Clock Active Indicators Autosel = M or H Si5322 and Si5323Clock Active Indicators Autosel = M or H Si5365 and Si5367 Automatic/Manual Clock Selection Input Clock Priority for Auto Switching Si5365, Si5366 Hitless Switching with Phase Build-Out Si5323, Si5366 Frame Synchronization Si5366 Recovery from Digital Hold Si5316, Si5323, Si5366Digital Hold/VCO Freeze Narrowband Digital Hold Si5316, Si5323, Si5366 Fsync Realignment Si5366 Output Phase Adjust Si5323, Si5366Using Fsout as a Fifth Output Clock Si5366 Including Fsync Inputs in Clock Selection Si5366 Output Clock Drivers Fsout Disable Control DblfsOutput Signal Format Selection Sfout DSBL2/BYPASS Pin Settings PLL Bypass ModeAlarms Alarm Output Logic Equations Frequency Offset Control Fosctl Lock Detect Retrigger Time Device ResetDSPLLsim Configuration Software Wideband PLL Divider Settings Si5325, Si5367 Input to Output Skew Si5325, Si5367 Loop Bandwidth Si5325, Si5367Lock Detect Si5325, Si5367 Signal Frequency Limits Dividers and Limits Initiating Internal Self-Calibration Loop Bandwidth Si5319, Si5326, Si5368, Si5375Low Loop Bandwidth Si5324, Si5327, Si5369, Si5374 Ckoutalwayson and Sqical Truth Table Input Clock Configurations Si5367 and Si5368 Input Clock Control Register Bits Manual Input Clock Selection Si5367, Si5368, Si5369Active Input Clock CKIN1,2,3,4 inputs CKIN1,3 & CKIN2,4 clock/FSYNC pairs Manual Input Clock Selection Si5324, Si5325, Si5326, Si5374 Ckselreg or CS pin Active Input Clock Input Clock Priority for Auto Switching Selected Clock Free Run Mode Programming Procedure Clock Control Logic in Free Run Mode Free Run Reference Frequency Constraints  While in Free Run Digital Hold Parameters in History Value of M Digital Hold History Delay Digital Hold History Averaging Time VCO Freeze Si5319, Si5325, Si5367, Si5375 Digital Hold versus VCO Freeze Coarse Skew Control Si5326, Si5368 Output Phase Adjust Si5326, Si5368Unlimited Coarse Skew Adjustment Si5326, Si5368 Fine Skew Control Si5326, Si5368 Independent Skew Si5324, Si5326, Si5368, Si5369, Si5374 Frame Synchronization Realignment Si5368 and Ckconfigreg =Output Phase Adjust Si5324, Si5327, Si5369, Si5374 Input-to-Output Skew All Devices CKIN3/CKIN4 Frequency Selection Ckconf = CKINn Frequency kHz Divisor CKOUT2 Frequency MHz NC5 Divider Setting KHz Fsout Common NC5 Divider SettingsAlignment Alarm Trigger Threshold Alarm Trigger Threshold Units of T CKOUT2 Including Fsync Inputs in Clock Selection Si5368 Using Fsout as a Fifth Output Clock Si5368Fsync Skew Control Si5368 Fsout Polarity and Pulse Width Control Si5368 Output Signal Format Selection Disabling CKOUTn Clock Validation Time Loss-of-Signal Validation TimesLoss-of-Signal Registers LOS Selection FOS Algorithm Si5324, Si5325, Si5326, Si5368, Si5369, Si5374 FOS Reference FOS Reference Clock SelectionCLKnRATE Registers Si5326 Si5368 LOS Si5319, Si5375 Fosen Alarm Output Logic Equations Si5368 and Ckconfigreg = 11.6. C1B, C2B, C3B, Alrmout Si5368 Ckconfigreg = Lock Detect Retrigger Time Lockt Device Interrupts I2C Command Format 13. I2C Serial Microprocessor Interface InstructionBYTE0 Address/Data70BYTE1 SPI Command FormatSerial Microprocessor Interface SPI Default Device Configuration Register Descriptions High-Speed I/O Input Clock Buffers CML/LVDS Termination 1.8, 2.5, 3.3 Output Driver Configuration Typical Output Circuits Disabling Unused Output Driver Output Driver Si5365, Si5366 Si5325, Si5326, Si5367, Si5368 Name Sfout Pin Sfout Code Single Diff Vocm Vpk-pk Output Format Measurements1,2Typical Clock Output Scope Shots Sfout2, Cmos Sfout3, lowSwingLVDS Sfout5, Lvpecl Sfout7, Lvds Cmos External Reference Circuit OSC-P Three-Level 3L Input Pins No External Resistors Parameter Symbol Min Max Three-Level 3L Input Pins With External Resistors Power Supply Typical Power Supply Bypass Network Tqfp Package Packages and Ordering Guide XA/XB Reference Sources and Frequencies Resonator/External Clock SelectionApproved Crystals RATE10 38.88MHz XO, 38.88MHz CKIN, 38.88MHz Ckout Fundamental Mode Crystals Reference DriftReference Jitter High f3 Value Phase Noise versus f3, 155.52 MHz in, 622.08 MHz outPhase Offset Frequency Hz DBc/Hz Noise Yellow-696.399 MHz output Blue-622.08 MHz output Reference vs. Output FrequencyMHz in, 622.08 MHz out, 696.399 MHz out MHz Out Jitter Bandwidth Yellow, fs RMS Blue, fs RMS High Reference Frequency MHz thru 163 MHz Ext Ref, 155.52 MHz in, 622.08 MHz out SONETOC192B, 4 MHz to 80 MHz MHz thru 180 MHz Ext Ref, 155.52 MHz in, 622.08 MHz outSONETOC192A, 20 kHz to 80 MHz SONETOC192C, 50 kHz to 80 MHz Appendix C-TYPICAL Phase Noise Plots 52 MHz In 622.08 MHz Out Loop BW = 7 Hz, Si5324 44 MHz In 156.25 MHz Out Loop BW = 80 Hz 44 MHz In 156.25 MHz Out Loop BW = 5 Hz, Si5324 130 44 MHz In 491.52 MHz Out Loop BW = 7 Hz, Si5324 08 MHz In 672.16 MHz Out Loop BW = 6.9 kHz 08 MHz In 672.16 MHz Out Loop BW = 100 Hz 25 MHz In 155.52 MHz Out 125 MHz In 644.531 MHz Out Jitter Values for Figure Jitter Bandwidth 644.531 MHz Jitter RMS 125 MHz In 690.569 MHz Out Jitter Values for Figure Jitter Bandwidth 690.569 MHz Jitter RMS 125 MHz In 693.493 MHz Out Jitter Values for Figure Jitter Bandwidth 693.493 MHz Jitter RMS Offset Frequency Hz MHz in, 173.371 MHz and 693.493 MHz outDBc/Hz Jitter Values for Figure 685 MHz In 173.371 MHz Out 685 MHz In 693.493 MHz Out Jitter Bandwidth MHz Input Jitter RMS MHz and 156.25MHz in, 622.08 MHz outDBc/Hz MHz In 1 GHz Out Jitter Band Digital Video HD-SDIMHz in, 148.5 MHz out Appendix D-ALARM Structure Si5368 Alarm Diagram 1 Si5368 Alarm Diagram 2 Pin # Si5316 Pull? Si5316 Pullup/DownSi5322 Pullup/Down Pin # Si5322 Pull? Pin # Si5323 Pull? Si5323 Pullup/DownSi5319, Si5324, Pullup/Down Pin # Si5326 Pull? Pin # Si5325 Pull? Si5325 Pullup/DownSi5326 Pullup/Down Pin # Si5327 Pull? Si5327 Pullup/DownSi5365 Pullup/Down Pin # Si5365 Pull? Si5366 Pullup/Down Pin # Si5366 Pull? Pin # Si5367 Pull? Si5367 Pullup/DownSi5368 Pullup/Down Pin # Si5368 Pull? Pin # Si5374/75 Pull? Si5369 Pullup/DownSi5374/75 Pullup/Down Bypass 622.08 MHz In, 622.08 MHz Out MHz in, 622.08 MHz out MHz in, 155.52 MHz out Bandwidth = 110 Hz Power Supply Noise RejectionPower Supply Noise to Output Transfer Function Out No crosstalk 155.52 MHz Clock Input Crosstalk Results Test ConditionsJitter Band MHz MHz out 622.084 MHz Hz loop KHz loop Clock Input Crosstalk Phase Noise Plots 5 .5 2 1 M H z in , 6 2 2 .0 8 4 M H z o u t Clock Input Crosstalk Detail View 155 .521 MHz in, 622 .084 MHz ou t Clock Input Crosstalk Wideband Comparison 155 .521 M H z in, 622.084 M H z out Clock Input Crosstalk Output of Rohde and Schwartz RF Output Format vs. Jitter Jitter vs. Output Format 19.44 MHz In, 622.08 MHz OutSpectrum Analyzer Agilent Model E444OA Hz in, 622.08 M Hz out MHz External XA-XB Reference Test ConditionsInput Frequency Variation = ±50 ppm Jitter, fs Input Frequency Input Frequency Variation = ±2000 ppm Jitter Values Fmod Fdev Jitter Start RF Gen Si5326 Si5324 MHz in, 622.08 MHz out RF Generator, Si5326, Si5324 No Jitter For Reference RF Generator, Si5326, Si5324 100 Hz Jitter RF Generator, Si5326, Si5324 1 kHz Jitter RF Generator, Si5326, Si5324 10 kHz Jitter Appendix I-Si5374AND Si5375 PCB Layout Recommendations Ground Plane and Reset Output Clock Routing Oscp Oscn Jitter, fsec RMS Si5374, Si5375 Crosstalk Test BedSi5374/75 Crosstalk Jitter Values Si5374, Si5375 Dspll a Si5374, Si5375 Dspll B Si5374, Si5375 Dspll C Si5374, Si5375 Dspll D Revision 0.41 to Revision Revision 0.3 to RevisionRevision 0.4 to Revision Revision 0.42 to Revision Rev 179 Contact Information