Micrel-Synergy's SY89429/30V frequency synthesizers designed used vari
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SY89429/30V FREQUENCY SYNTHESIS
Micrel-Synergy's SY89429/30V frequency synthesizers designed used various clock subsystems. Primary function product synthesize clock frequencies required systems needing high quality, jitter clock source. cost other clock sources, either crystal oscillators, increase dramatically precision/frequency requirements digital systems push into 100+ arena. Many cost CMOS frequency synthesizers appeared market last years. Unfortunately, these products have relatively high jitter limited operating frequency range. Therefore, their applications limited lower precision/lower frequencies. SY89429/30V, designed with Micrel-Synergy's high performance ASSETBipolar technology differential circuit technology throughout, perfect cost alternative expensive crystal oscillators. Unlike other frequency synthesizers, SY89429/30V extremely jitter high supply noise rejection that famous for. Because devices programmable between 25MHz 950MHz using 16MHz crystal, different system frequency requirements same device. This dramatically reduce inventory costs management additional products otherwise required achieve these various frequencies. This programmability also makes board/ system speed grading possible part normal production flow without multiple oscillators. This provides higher overall yield lower manufacturing cost. addition cost savings, there many other benefits using SY89429/30V. Normal system production testing incorporate frequency margining that unavailable fixed frequency designs crystal oscillators. This capability leads directly higher product quality reliability. Furthermore, SY89429/30V programmed small steps (1MHz steps with 16.000MHz crystal). Other precise frequencies programmed well. section titled "Advanced Frequency Control Applications." This ability provide frequency eliminates need high cost custom oscillator alternatives. Throughout this application note refer frequency range 25MHz 950MHz. This only simplicity reasons make application note applicable both devices. range SY89429V SY89430V different. That SY89429V internal range 400MHz 800MHz external output frequency 25MHz 400MHz. SY89430V internal range 400MHz 950MHz external output frequency 50MHz 950MHz.
APPLICATION NOTE AN-07
General Requirements
Operating SY89429/30V very simple. Very cost external components required. These cost external components provide tuning capability needed optimize minimize jitter characteristics each individual system application. achieve best possible performance jitter power supply noise rejection, basic high speed design guidelines should followed.
Power Supply Requirements
SY89429/30V designed operate with single positive supply either +3.3V +5V. FOUT /FOUT (the differential PECL outputs) will interface PECL inputs using same supply voltage. However, SY89429/30V also used true systems. this application, please refer section titled "True Design."
Power Supply Filtering Techniques
high speed integrated circuits, power supply filtering very important. 0.1µF high frequency by-pass capacitor should used between separate power supply pins ground. VCC1, VCC_QUIET, VCC_TTL VCC_OUT should individually connected power supply plane through vias, by-pass capacitor should used each pin. achieve optimum jitter performance, better power supply isolation required. this case ferrite bead along with 0.01µF by-pass capacitor should connected each power supply pin. Figure shows connections power supply filtering using ferrite beads.
Termination PECL Outputs
differential PECL outputs, FOUT /FOUT, open emitter outputs. Therefore, terminating resistors current sources must used functionality. These outputs designed drive transmission lines. Matched impedance techniques should used maximize operating frequency minimize wave-form distortion. There simple termination schemes. Figure shows three simple termination circuits system.
Interface Inputs
SY89429/30V designed interface with compatible signals. inputs except XTAL1 XTAL2 compatible. These inputs have internal pull resistors. Therefore, inputs left open-open inputs logical state. Although inputs left open, recommended that open inputs connected power supply line. These inputs connected power supply line (VCC logical "1") ground line (VEE logical "0") directly through series resistors. Alternatively, these inputs also driven directly from compatible signals. XTAL1 XTAL2 inputs should only connected crystal.
Rev.: Amendment:
Issue Date: February 2000
Micrel
APPLICATION NOTE AN-07
Input Reference Frequency On-Chip Crystal Oscillator
SY89429/30V designed based input reference frequency 16MHz phase detector frequency 2MHz. using other input reference frequencies, refer section titled "Advanced Frequency Control Applications." Using 16MHz reference frequency, output frequency programmed from 25MHz 950MHz 1MHz steps. input crystal oscillator requires only off-chip 16MHz reference crystal connected between XTAL1 XTAL2 pins. Figure shows recommended crystal oscillator circuit.
Filter Design
filter Phase Locked Loop (PLL) based device deserves special attention. SY89429/30V provides filter pins external filter. simple three-component passive filter recommended achieving ultra jitter. Figure shows recommended three-components. differential design, filter connected between LOOP_FILTER LOOP_REF pins. With this configuration, extremely high supply noise rejection achieved. important that filter circuit filter pins isolated from non-common mode coupling placed plane.
Using On-Board Crystal Oscillator
SY89429/30V features fully integrated on-board crystal oscillator minimize system implementation costs. oscillator series resonant, multivibrator type design opposed more common parallel resonant oscillator design. series resonant design provides better stability eliminates need large chip capacitors. oscillator somewhat sensitive loading inputs user advised mount crystal close SY89429/ possible avoid board level parasitics. facilitate co-location surface mount crystals recommended, required. oscillator circuit series resonant circuit thus optimum performance series resonant crystal should used. Unfortunately most crystals characterized parallel resonant mode. Fortunately there physical difference between series resonant parallel resonant crystal. difference purely devices characterized. result parallel resonant crystal used with SY89429/30V with only minor error desired frequency. parallel resonant mode crystal used series resonant circuit will exhibit frequency oscillation hundred lower than specified, hundred translates inaccuracies. general computer application this level inaccuracy immaterial. Table specifies performance requirements crystals used with SY89429/30V.
Parameter Crystal Resonance Frequency Tolerance Frequency/Temperature Stability Operating Range Shunt Capacitance Equivalent Series Resistance (ESR) Correlation Drive Level Aging Value Fundamental Series Resonance* ±75ppm 25°C ±150ppm 70°C 70°C 5-7pF 100µW 5ppm/Yr (First Years)
Table Crystal Specifications
Generating High-Speed Clock Signals
high speed PECL-to-TTL translator such SY10/ 100ELT23 SY10/100ELT23L (for +3.3V) used generate high speed compatible signals. High speed PECL-to-TTL translating Clock Drivers such SY10/ 100H841/842 SY10/100H641/646 added multiple copies such clocks desired. volt power supply operation, following PECL-to-TTL translating clock drivers SY10/100H841L/842L SY10/ 100H641L/646L used. These translators capable driving 50pF loads 160MHz.
True Design
SY89429/30V designed TTL/PECL systems. However, designed into pure environment easily. Connect pins ground pins -3.3V, -4.5V -5.2V) power supply line. With this operating condition, FOUT /FOUT interface directly with normal 100K signals. other inputs have internal pull resistors. Therefore, input left open open inputs logical state. Although inputs allowed open, recommended that open inputs connected power supply line. These inputs connected ground lines volt logical "1") negative power supply lines (-3.3V, -4.5V -5.2V logical "0") directly through series resistors. These inputs interface normal signals with SY100ELT23 signal translation. Figure shows schematic with signal translations.
Advanced Frequency Control Applications
primary function these products synthesize clock frequencies from 25MHz 950MHz 1MHz steps with 16.00MHz crystal. However, there many other applications that obvious. Even though SY89429/30V said able generate frequencies between 25MHz 950MHz 1MHz steps with 16MHz crystal, output frequency programmed properly configuring internal dividers represented this formula (See Table application example):
Micrel
APPLICATION NOTE AN-07
FOUT
FXTAL FXTAL
Step Size
Crystal oscillator frequency designed less than 25MHz using fundamental crystal. Input frequencies limited above 6.26MHz minimum frequency 400MHz. Using FOUT equation, very easy determine what values must certain multiplication factor.
FVCO where
FXTAL
FXTAL crystal frequency input reference frequency
frequency multiplier (from 511) post divider (1,2,4,8, FVCO frequency (400MHz 950MHz)
Micrel
APPLICATION NOTE AN-07
SY89429/30V R=Zo R=Zo 0.1µF
PECL PECL Input INPUT
<<Zo
Reg.
SY89429/30V R=Zo R=Zo 0.1µF R=2Zo
PECL Input
R=5/3Z SY89429/30V R=5/2Zo R=5/2Zo PECL Input R=5/3Zo
Figure Matched Impedance Termination Schemes Systems
Micrel
APPLICATION NOTE AN-07
+3.3V Zo=100
+3.3V
SY89429/30V
PECL Inputs INPUT
+3.3V SY89429/30V +3.3V R=Zo R=Zo 0.1µF
+3.3V
PECL PECL Inputs INPUT
R=Zo
+3.3V SY89429/30V R=5/2Zo
+3.3V +3.3V R=5/2Zo PECL PECL Inputs INPUT
R=5/3Zo
R=5/3Zo
Figure Matched Impedance Termination Schemes 3.3V Systems
Micrel
APPLICATION NOTE AN-07
XTAL1
XTAL2
16MHz
Figure Recommended External Components Crystal Oscillator
LOOP_FILTER
LOOP_REF
3300pF
0.47µF
Figure Recommended Passive Filter Circuit
Micrel
External requirements SY89429/30V (needed insure ±25ps jitter). Ferrite bead BLM21A102F quiet power External loop filter Small 0805 0.22µF 1.0µF LOOP_FILTER LOOP_REF VCC_QUIET FREF Ferrite bead BLM31P500S +3.3V +5.0V Small 0805 680pF 1000pF
+3.3V +5.0V
1206 size
3300pF 0.47µF
External filter components 0805 size
+3.3V +5.0V logic power
PHASE DETECTOR T110 VCC_OUT 400-950
XTAL1 XTAL2
FOUT
9-BIT COUNTER
10-25MHz Fundamental Crystal
FOUT FOUT
Figure Power Supply Filtering
LATCH LATCH LATCH 9-BIT 2-BIT 3-BIT VCC1 6,21 M[8:0] 17,18 N[1:0] 19,22 Small 0805 680pF 1000pF
S_LOAD
S_CLOCK FOUT FREF HIGH
P_LOAD
TEST
S_DATA
Keep traces short possible between filter pins. three external loop filter components need kept close possible kept close each other.
S_CLOCK
Notes: numbers reference PLCC pinout. ferrite beads made MuRata.
+3.3V +5.0V
Ferrite bead BLM21A102F equivalent
logic power
APPLICATION NOTE AN-07
Small 0805 0.22µF 1.0µF
Micrel
APPLICATION NOTE AN-07
FOUT SY89429/30V ELT23 ELT23L Input
-3.3V -5.2V
Figure Interfacing SY89429/30V Inputs with Signals True Designs
MICREL-SYNERGY
3250 SCOTT BOULEVARD SANTA CLARA 95054
(408) 980-9191
(408) 914-7878
http://www.micrel.com
This information believed accurate reliable, however responsibility assumed Micrel infringement patents other rights third parties resulting from use. license granted implication otherwise under patent patent right Micrel Inc. 2000 Micrel Incorporated
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