DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR differential LVDS
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ICS8745-21
DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
differential LVDS output pair designed meet exceed requirements ANSI TIA/EIA-644 differential feedback output pair Differential CLK, nCLK input pair CLK, nCLK pair accept following differential input levels: LVDS, LVPECL, LVHSTL, SSTL, HCSL Output frequency range: 31.25MHz 700MHz Input frequency range: 31.25MHz 700MHz range: 250MHz 700MHz External feedback "zero delay" clock regeneration with configurable frequencies Programmable dividers allow following output-to-input frequency ratios: 8:1, 4:1, 2:1, 1:1, 1:2, 1:4, Cycle-to-cycle jitter: 25ps (maximum) Static phase offset: 50ps 150ps 3.3V supply voltage 70°C ambient operating temperature Industrial temperature information available upon request
GENERAL DESCRIPTION
ICS8745-21 highly versatile LVDS clock generator member HiPerClockSHiPerClockSfamily High Performance Clock Solutions from ICS. ICS8745-21 fully integrated configured zero delay buffer, multiplier divider, output frequency range 31.25MHz 700MHz. Reference Divider, Feedback Divider Output Divider each programmable, thereby allowing following outputto-input frequency ratios: 8:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:8. external feedback allows device achieve "zero delay" between input clock output clocks. PLL_SEL used bypass system test debug purposes. bypass mode, reference clock routed around into internal output dividers.
BLOCK DIAGRAM
PLL_SEL
÷16, ÷32,
ASSIGNMENT
nQFB nCLK nFB_IN FB_IN SEL2 VDDO nQFB SEL1 SEL0 PLL_SEL VDDA SEL3 VDDO
nCLK
8:1, 4:1, 2:1, 1:1, 1:2, 1:4,
FB_IN nFB_IN
ICS8745-21
20-Lead, 300-MIL SOIC 7.5mm 12.8mm 2.3mm body package Package View
SEL0 SEL1 SEL2 SEL3
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
Type Description
TABLE DESCRIPTIONS
Number Name nCLK nFB_IN FB_IN SEL2 VDDO SEL3 VDDA PLL_SEL SEL0 SEL1 Input Input Input Input Input Input Power Power Output Input Power Input Power Input Input Pullup Pulldown Non-inver ting differential clock input. Inver ting differential clock input. Active HIGH Master Reset. When logic HIGH, internal dividers reset causing true outputs inver outputs Pulldown high. When logic LOW, internal dividers outputs enabled. LVCMOS LVTTL interface levels. Pullup Feedback input phase detector regenerating clocks with "zero delay". Pulldown Feedback input phase detector regenerating clocks with "zero delay". Pulldown Determines output divider values Table LVCMOS LVTTL interface levels. Output supply pins. Differential feedback outputs. LVDS interface levels. Power supply ground. Differential clock outputs. LVDS interface levels. Pulldown Determines output divider values Table LVCMOS LVTTL interface levels. Analog supply pin. Selects between reference clock input dividers. When HIGH, selects PLL. When LOW, selects reference clock. LVCMOS LVTTL interface levels. Core supply pin. Pullup
nQFB, Output
Pulldown Determines output divider values Table LVCMOS LVTTL interface levels. Pulldown Determines output divider values Table LVCMOS LVTTL interface levels.
NOTE: Pullup Pulldown refer internal input resistors. Table Characteristics, typical values.
TABLE CHARACTERISTICS
Symbol RPULLUP RPULLDOWN Parameter Input Capacitance Input Pullup Resistor Input Pulldown Resistor Test Conditions Minimum Typical Maximum Units
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Outputs PLL_SEL Enable Mode QFB; nQFB
TABLE CONTROL INPUT FUNCTION TABLE
Inputs SEL3 SEL2 SEL1 SEL0 Reference Frequency Range (MHz)* 62.5 31.25 87.5 62.5 -700 62.5 31.25 87.5 62.5 31.25 87.5 31.25 87.5
*NOTE: frequency range configurations above 700MHz.
TABLE BYPASS FUNCTION TABLE
Inputs SEL3
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SEL2
SEL1
SEL0
Outputs PLL_SEL Bypass Mode QFB; nQFB
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
4.6V -0.5V -0.5V VDDO 0.5V 47.9°C/W lfpm) -65°C 150°C NOTE: Stresses beyond those listed under Absolute Maximum Ratings cause permanent damage device. These ratings stress specifications only. Functional operation product these conditions conditions beyond those listed Characteristics Characteristics implied. Exposure absolute maximum rating conditions extended periods affect product reliability.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, Inputs, Outputs, Package Thermal Impedance, Storage Temperature, TSTG
TABLE POWER SUPPLY CHARACTERISTICS, VDDA VDDO 3.3V±5%, 70°C
Symbol VDDA VDDO IDDA IDDO Parameter Core Supply Voltage Analog Supply Voltage Output Supply Voltage Power Supply Current Analog Supply Current Output Supply Current Test Conditions Minimum 3.135 3.135 3.135 Typical Maximum 3.465 3.465 3.465 Units
TABLE LVCMOS/LVTTL CHARACTERISTICS, VDDA VDDO 3.3V±5%, 70°C
Symbol Parameter Input High Voltage Input Voltage Input High Current SEL0, SEL1, SEL2, SEL3 PLL_SEL SEL0, SEL1, SEL2, SEL3 Input Current PLL_SEL 3.465V, -150 3.465V 3.465V 3.465V, Test Conditions Minimum -0.3 Typical Maximum Units
TABLE DIFFERENTIAL CHARACTERISTICS, VDDA VDDO 3.3V±5%, 70°C
Symbol Parameter VCMR Input High Current Input Current CLK, FB_IN nCLK, nFB_IN CLK, FB_IN nCLK, nFB_IN Test Conditions 3.465V 3.465V 3.465V, 3.465V, -150 0.15 0.85 Minimum Typical Maximum Units
Peak-to-Peak Input Voltage Common Mode Input Voltage; NOTE
NOTE Common mode voltage defined VIH. NOTE single ended applications, maximum input voltage CLK, nCLK 0.3V.
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
Test Conditions Minimum 1.125 Typical 1.25 -3.5 VDD, VOUT 3.465V, -3.5 1.34 1.06 Maximum 1.375 Units
TABLE LVDS CHARACTERISTICS, VDDA VDDO 3.3V±5%, 70°C
Symbol IOSD IOFF Parameter Differential Output Voltage Magnitude Change Offset Voltage Magnitude Change Differential Output Shor Circuit Current Output Shor Circuit Current Power Leakage Output Voltage High Output Voltage
TABLE INPUT FREQUENCY CHARACTERISTICS, VDDA VDDO 3.3V±5%, 70°C
Symbol Parameter Input Frequency CLK, nCLK Test Conditions PLL_SEL PLL_SEL Minimum 31.25 Typical Maximum Units
TABLE CHARACTERISTICS, VDDA VDDO 3.3V±5%, 70°C
Symbol fMAX Parameter Output Frequency Propagation Delay; NOTE Output Skew; NOTE Static Phase Offset; NOTE Cycle-to-Cycle Jitter; NOTE Phase Jitter; NOTE Output Pulse Width Lock Time tPERIOD/2 tPERIOD/2 PLL_SEL 700MHz PLL_SEL PLL_SEL 3.3V -100 Test Conditions Minimum Typical Maximum tPERIOD/2 Units
tsk(o) tjit(cc) tjit()
Output Rise/Fall Time 50MHz parameters measured fMAX unless noted otherwise. NOTE Measured from differential input crossing point differential output crossing point. NOTE Defined time difference between input reference clock averaged feedback input signal across conditions, when locked input reference frequency stable. NOTE Phase jitter dependent input source used. NOTE Defined skew between outputs same supply voltage with equal load conditions. Measured output differential cross points. NOTE This parameter defined accordance with JEDEC Standard NOTE Characterized frequency 622MHz.
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
PARAMETER MEASUREMENT INFORMATION
3.3V
3.3V±5% POWER SUPPLY
SCOPE
nCLK
Float
LVDS
Cross Points
3.3V OUTPUT LOAD TEST CIRCUIT
DIFFERENTIAL INPUT LEVEL
nCLK CLK0 nFB_IN FB_IN
tsk(o)
mean Phase Jitter mean Static Phase Offset
(where random sample, mean average sampled cycles measured controlled edges)
PHASE JITTER
STATIC PHASE OFFSET
OUTPUT SKEW
nCLK, nQFB CLK,
Clock Outputs
PROPAGATION DELAY
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OUTPUT RISE/FALL TIME
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ICS8745-21
DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
nQFB
Input
Pulse Width PERIOD
VOS/
tPERIOD
SETUP
Input
LVDS
VOD/
Input
LVDS
SETUP
IOSD SETUP
Input
LVDS
IOSB
LVDS
IOFF
SETUP
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IOFF SETUP
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LVDS
IOSD
ICS8745-21
DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR APPLICATION INFORMATION
WIRING DIFFERENTIAL INPUT ACCEPT SINGLE ENDED LEVELS
Figure shows differential input wired accept single ended levels. reference voltage V_REF VDD/2 generated bias resistors This bias circuit should located close possible input pin. ratio
might need adjusted position V_REF center input voltage swing. example, input clock swing only 2.5V 3.3V, V_REF should 1.25V R2/R1 0.609.
CLK_IN V_REF 0.1uF
FIGURE SINGLE ENDED SIGNAL DRIVING DIFFERENTIAL INPUT
POWER SUPPLY FILTERING TECHNIQUES
high speed analog circuitry, power supply pins vulnerable random noise. ICS8745-21 provides separate power supplies isolate high switching noise from outputs internal PLL. VDD, VDDA, VDDO should individually connected power supply plane through vias, bypass capacitors should used each pin. achieve optimum jitter performance, power supply isolation required. Figure illustrates resistor along with 10µF .01µF bypass capacitor should connected each VDDA pin.
3.3V .01µF VDDA .01µF
FIGURE POWER SUPPLY FILTERING
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Integrated Circuit Systems, Inc. LAYOUT GUIDELINE
schematic ICS8745-21 layout example shown Figure ICS8745-21 recommended board layout this example shown Figure This layout example used general guideline. layout actual system will
ICS8745-21
DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
depend selected component types, density components, density traces, stack P.C. board.
3.3V
(155.52 MHz)
nCLK nFB_IN FB_IN SEL2 VDDO nQFB SEL1 SEL0 VDDI PLL_SEL VDDA SEL3 VDDO SEL1 SEL0 PLL_SEL VDDA SEL3 0.1uF 0.01u VDDO
3.3V PECL Driver SEL2 VDDO
8745-21
Space (i.e. intstalled)
(77.76 MHz)
PLL_SEL SEL0 SEL1 SEL2 SEL3
Bypass capacitors located near power pins
(U1-7)
VDDO
(U1-11)
VDD=3.3V VDDO=3.3V
LVDS_input
0.1uF
0.1uF
SEL[3:0] 0101, Divide
FIGURE ICS8745-21 LVDS ZERO DELAY BUFFER SCHEMATIC EXAMPLE
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following component footprints used this layout example: resistors capacitors size 0603.
ICS8745-21
DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
trace delay might restricted available space board component location. While routing traces, clock signal traces should routed first should locked prior routing other signal traces. differential output traces should have same length. Avoid sharp angles clock trace. Sharp angle turns cause characteristic impedance change transmission lines. Keep clock traces same layer. Whenever possible, avoid placing vias clock traces. Placement vias traces affect trace characteristic impedance hence degrade signal integrity. prevent cross talk, avoid routing other signal traces parallel with clock traces. running parallel traces unavoidable, allow separation least three trace widths between differential clock trace other signal trace. Make sure other signal traces routed between clock trace pair. matching termination resistors should located close receiver input pins possible.
POWER
GROUNDING
Place decoupling capacitors close possible power pins. space allows, placement decoupling capacitor component side preferred. This reduce unwanted inductance between decoupling capacitor power caused via. Maximize power ground sizes number vias capacitors. This reduce inductance between power ground planes component power ground pins. filter consisting C11, should placed close VDDA possible.
CLOCK TRACES
TERMINATION
Poor signal integrity degrade system performance cause system failure. synchronous high-speed digital systems, clock signal less tolerant poor signal integrity than other signals. ringing rising falling edge excessive ring back cause system failure. shape trace
ICS8745-21
VDDO
VDDA
Traces
FIGURE BOARD LAYOUT ICS8745-21
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR RELIABILITY INFORMATION
TABLE JAVS. FLOW TABLE
Velocity (Linear Feet Minute)
Single-Layer PCB, JEDEC Standard Test Boards Multi-Layer PCB, JEDEC Standard Test Boards 83.2°C/W 46.2°C/W
65.7°C/W 39.7°C/W
57.5°C/W 36.8°C/W
NOTE: Most modern designs multi-layered boards. data second pertains most designs.
TRANSISTOR COUNT
transistor count ICS8745-21 3050
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
PACKAGE OUTLINE SUFFIX
TABLE PACKAGE DIMENSIONS
SYMBOL 10.00 0.25 0.40 -0.10 2.05 0.33 0.18 12.60 7.40 1.27 BASIC 10.65 0.75 1.27 Millimeters Minimum 2.65 -2.55 0.51 0.32 13.00 7.60 Maximum
Reference Document: JEDEC Publication MS-013, MO-119
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DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
TABLE ORDERING INFORMATION
Part/Order Number ICS8745AM-21 ICS8745AM-21T Marking ICS8745AM-21 ICS8745AM-21 Package Lead SOIC Lead SOIC Tape Reel Count Tube 1000 Temperature 70°C 70°C
While information presented herein been checked both accuracy reliability, Integrated Circuit Systems, Incorporated (ICS) assumes responsibility either infringement patents other rights third parties, which would result from use. other circuits, patents, licenses implied. This product intended normal commercial applications. other applications such those requiring extended temperature range, high reliability, other extraordinary environmental requirements recommended without additional processing ICS. reserves right change circuitry specifications without notice. does authorize warrant product life support devices critical medical instruments. 8745AM-21
REV. FEBRUARY 2003
ICS8745-21
DIFFERENTIAL-TO-LVDS ZERO DELAY CLOCK GENERATOR
REVISION HISTORY SHEET Description Change Revised Block Diagram. Added Output Skew 15ps Max. Added Output Skew Diagram. Added note bottom table. Added Note Changed inputs from LVDS interface levels LVCMOS interface levels. Revised VCMR from "VDD 0.5" Minimum "GND 0.5" Minimum Revised Features notes. Characteristics table revised first line notes. Description Table, revised description. Description table revised descriptions. Corrected Function Table headings from "Q0:Q4, nQ0:nQ4" QFB; nQFB". Power Supply table added IDDO spec 20mA. revised parameter descriptions. Characteristics table spec, changed tcycle tPERIOD combined Updated Single Ended Signal Diagram. added Power Supply Filtering Techniques section. Updated Figure schematic. Updated format. Date 10/31/01 11/19/01 11/29/01 11/30/01 5/10/02 5/15/02 8/15/02
Table
Page
2/12/03
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