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19-5214; Rev 0; 4/10
Spread-Spectrum Clock Generators
General Description
The MAX31C80/MAX31D80 are spread-spectrum clock generators that contain a phase-locked loop (PLL) that generates a 2MHz to 134MHz clock from an input clock or crystal. The PLL can provide a spread-spectrum down-dithered (MAX31D80) or center-dithered (MAX31C80) frequency-modulated clock. The devices also buffer the incoming clock and provide this output on a separate pin. The MAX318C80/MAX31D80 are provided in a 10-pin TDFN package and operate over a full -40NC to +125NC automotive temperature range. Devices can be factory programmed for multiple combinations of input and output frequencies (see the Ordering Information table). A low-cost, low-frequency crystal can be used at the input to generate frequencies up to 134MHz. Generator
S Input Can Be Either an 8MHz to 34MHz Crystal or
Features
S 2MHz to 134MHz Spread-Spectrum Clock
MAX31C80/MAX31D80
8MHz to 134MHz Clock
S Factory-Programmable Output Frequencies in
2MHz to 134MHz Range
S Low-Cost Crystal at Low Frequency Used to
Generate High Frequencies
S On-Board PLL is Capable of Spread-Spectrum
Frequency Modulation
S Down- or Center-Dither Spread-Spectrum
Frequency Modulation
S User-Configurable Spread-Spectrum Dither
Typical Application Circuit
fIN = 27MHz
Magnitude
S Low Cycle-to-Cycle Jitter S 3.3V Supply Voltage S Temperature Range: -40NC to +125NC S Small Package: 10-Pin TDFN (3mm x 3mm x
0.8mm)
fIN = 27MHz X1 MAX31D80 VCC SMSEL1 SMSEL0 GND X2
Applications
27MHz CLOCK fCLKOUT = 100MHz 1.5% DOWN DITHERED VCC
XOUT CLKOUT
Graphics Cards Set-Top Boxes Automotive Infotainment Printers
VCC
DECOUPLING CAPACITOR
Ordering Information
PART MAX31C80T-xxx+ MAX31C80T-xxx+T MAX31D80T-xxx+ MAX31D80T-xxx+T TEMP RANGE -40NC to +125NC -40NC to +125NC -40NC to +125NC -40NC to +125NC DITHER MODE Center Center Down Down PIN-PACKAGE 10 TDFN-EP* 10 TDFN-EP* 10 TDFN-EP* 10 TDFN-EP*
xxx = Factory-programmable output frequency and dither rate (see the Selector Guide table). +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad.
Selector Guide appears at end of data sheet.
_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Spread-Spectrum Clock Generators MAX31C80/MAX31D80
ABSOLUTE MAXIMUM RATINGS
Voltage Range on VCC Relative to GND..............-0.3V to +4.3V Voltage Range on Any Other Pin Relative to GND .................................... -0.3V to (VCC + 0.3V)* Continuous Power Dissipation (TA = +70C) 10-Pin TDFN (derate 24.4mW/C above +70C) .....1951.2mW *Not to exceed +4.3V.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Storage Temperature Range............................ -55NC to +135NC Lead Temperature (soldering, 10s) ................................+300NC Soldering Temperature (reflow) ......................................+260NC
RECOMMENDED OPERATING CONDITIONS
(TA = -40NC to +125NC.) PARAMETER Supply Voltage Input Logic 0 (SMSEL0 and SMSEL1) Input Logic 1 (SMSEL0 and SMSEL1) Input Logic Unconnected (SMSEL0 and SMSEL1) Input Logic 0 for X1 Input Logic 1 for X1 XOUT Load CLKOUT Load Crystal Frequency Clock Input Frequency Crystal ESR Clock Input Duty Cycle Crystal Parallel Load Capacitance SYMBOL VCC VIL VIH VIF VIL:X1 VIH:X1 CL:XOUT 2MHz P fCLKOUT < 67MHz CL:CLKOUT fIN fIN XESR fINDC CCL 40 67MHz P fCLKOUT < 101MHz 101MHz P fCLKOUT P 134MHz 8 8 Limits are in case user wants to force voltage instead of unconnecting this pin CONDITIONS MIN 3.0 -0.3 0.75 x VCC 0.4 x VCC -0.3 0.7 x VCC TYP 3.3 MAX 3.6 0.25 x VCC VCC + 0.3 0.55 x VCC 0.3 x VCC VCC + 0.3 15 15 10 7 34 134 90 60 18 MHz MHz I % pF pF UNITS V V V V V V pF
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Spread-Spectrum Clock Generators
DC ELECTRICAL CHARACTERISTICS
(3.0V P VCC P 3.6V, TA = -40NC to +125NC, unless otherwise noted.) PARAMETER Supply Current Input Leakage (SMSEL0 and SMSEL1) Low-Level Output Voltage (XOUT and CLKOUT) High-Level Output Voltage (XOUT and CLKOUT) Input Capacitance (X1 and X2) SYMBOL IDD IIL VOL VOH CIN CONDITIONS fIN = 27MHz, fCLKOUT = 100MHz, down dithered, CL = 10pF SMSEL_ = GND or VCC IOL = 10mA IOH = -10mA VCC 0.2 5 MIN TYP 22 Q15 0.2 MAX UNITS mA FA V V pF
MAX31C80/MAX31D80
AC ELECTRICAL CHARACTERISTICS
(3.0V P VCC P 3.6V, TA = -40NC to +125NC, unless otherwise noted.) PARAMETER CLKOUT Duty Cycle XOUT Duty Cycle Rise Time Fall Time Dither Rate Range Dither Rate Accuracy Peak Cycle-to-Cycle Jitter Power-Up Time tJ tPUP CLKOUT = 100MHz, 10,000 cycles, TA = +25NC VCC valid to output active, TA = +25NC, VCC = 3.3V SYMBOL fCLKOUT:DC fXOUT:DC tR tF fDR CONDITIONS CL:CLKOUT = 7pF CL:XOUT = 7pF, TA = +25NC, VCC = 3.3V CL:CLKOUT = 7pF CL:CLKOUT = 7pF Factory programmable 20 -4 75 1 MIN 40 40 1.6 1.6 40 +4 TYP MAX 60 60 % ns ns kHz % ps ms UNITS
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Spread-Spectrum Clock Generators MAX31C80/MAX31D80
Typical Operating Characteristics
(VCC = +3.3V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX31C80 toc01
SUPPLY CURRENT vs. TEMPERATURE
MAX31C80 toc02
SUPPLY CURRENT vs. OUTPUT FREQUENCY
VCC = 3.3V
MAX31C80 toc03
27 25 SUPPLY CURRENT (mA) 23 21 19 17 15
fIN = 27MHz fCLKOUT = 100MHz
29 27 SUPPLY CURRENT (mA) 25 23 21 19 17 15
fIN = 27MHz fCLKOUT = 100MHz
25 20 SUPPLY CURRENT (mA) 15 10 5 0
VCC = 3.6V
TA = +125C TA = +25C TA = -40C
VCC = 3.3V VCC = 3.0V
-40 -15 10 35 60 85 110
3.0
3.2
3.4
3.6
8
32
56
80
104
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
OUTPUT FREQUENCY (MHz)
DUTY CYCLE vs. SUPPLY VOLTAGE
MAX31C80 toc04
DUTY CYCLE vs. TEMPERATURE
58 56 DUTY CYCLE (%) 54 52 50 48 46 44 42 40
58 56 DUTY CYCLE (%) 54 52 50 48 46 44 42 40
fCLKOUT = 100MHz
fCLKOUT = 100MHz
TA = +125C TA = +25C
VCC = 3.6V
VCC = 3.3V
TA = -40C
VCC = 3.0V
3.0
3.2
3.4
3.6
-40
10
60
110
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
FREQUENCY SPECTRUM AT 122MHz WITH CENTER SPREAD
MAX31C80 toc06
FREQUENCY SPECTRUM AT 100MHz WITH DOWN DITHER
fCLKOUT = 100MHz CENTER DITHER = -3% -16.56dB
MAX31C80 toc07
0 -10 ATTENUATION (dB) -20 -30 -40 -50
fCLKOUT = 122MHz CENTER DITHER = 1.5% -14.23dB
0 -10 ATTENUATION (dB) -20 -30 -40 -50 -60
-60 119.2
121.2
123.2
96
98 FREQUENCY (MHz)
100
FREQUENCY (MHz)
4
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MAX31C80 toc05
60
60
Spread-Spectrum Clock Generators
Block Diagram
8MHz TO 134MHz CLOCK OR 8MHz TO 34MHz CRYSTAL fIN MAX31C80 MAX31D80 X1 X2 CRYSTAL OSCILLATOR PROGRAMMABLE PLL WITH SPREAD SPECTRUM VCC VCC CLKOUT (fCLKOUT = 2MHz TO 134MHz) XOUT (fXOUT = fIN) GND
MAX31C80/MAX31D80
SMSEL0 SMSEL1
SPREAD-SPECTRUM MAGNITUDE CONTROL
Pin Configuration
XOUT 6 EP 2 SMSEL0 3 VCC 4 GND 5 CLKOUT GND 7 VCC 8 MAX31C80 MAX31D80
TOP VIEW
X2 10 X1
+
1
SMSEL1 9
TDFN
Pin Description
PIN NAME FUNCTION Crystal Drive/Clock Input. A crystal with the proper loading is connected across X1 and X2. Instead of a crystal, a clock can be applied at the X1 input. If no clock or crystal is present, then no clock is output at either XOUT or CLKOUT. Spread-Spectrum Magnitude Select. These are three-state digital inputs to determine the spread-spectrum magnitude. Tables 1 and 2 provide details for configuration of these pins for down and center dither, respectively. PIN 3, 8 4, 7 5 6 NAME VCC GND CLKOUT XOUT Ground Clock Output. Spread-spectrum-capable digital output clock from the PLL. Crystal Buffered Output. Buffered digital output of the input crystal or clock. Crystal Drive Output. A crystal with the proper loading is connected across X1 and X2. If a clock is applied at the X1 input, then X2 should be left open circuit. Exposed Pad. Connect to GND. 5 FUNCTION Supply Voltage
1
X1
2, 9
SMSEL0, SMSEL1
10
X2
--
EP
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Spread-Spectrum Clock Generators MAX31C80/MAX31D80
Detailed Description
The MAX31C80/MAX31D80 modulate an input clock to generate a center-dithered or down-dithered spreadspectrum output. An 8MHz to 27MHz crystal or 8MHz to 134MHz oscillator input is applied to the device. An internal PLL dithers the output clock at a user-selectable magnitude to produce a down-dithered or centerdithered output clock. The output clock's frequency is programmable from 2MHz to 134MHz. The devices also buffer the incoming clock and provide this output on a separate pin. The MAX31D80 can generate down-dithered magnitudes up to -3%. The MAX31C80 can generate center-dithered magnitudes up to P 1.5%. The desired magnitude is selected using the input pins SMSEL1 and SMSEL0 as shown in Tables 1 and 2. A power cycle is required after each change of the dither magnitude for the changes to take effect.
Spread-Spectrum Dither Magnitude
Table 1. Spread-Spectrum Mode and Magnitude Select (for Down Dither)
SMSEL1 0 0 0 Unconnected Unconnected Unconnected 1 1 1 SMSEL0 0 Unconnected 1 0 Unconnected 1 0 Unconnected 1 0 to -0.25 0 to -0.375 0 to -0.5 0 to -0.75 0 to -1.0 0 to -1.5 0 to -2.0 0 to -3.0 Down Dither SPREAD-SPECTRUM MAGNITUDE SELECTED (%) SPREAD-SPECTRUM DITHER MODE SELECTED Spread-Spectrum Disabled
Table 2. Spread-Spectrum Mode and Magnitude Select (for Center Dither)
SMSEL1 0 0 0 Unconnected Unconnected Unconnected 1 1 1 SMSEL0 0 Unconnected 1 0 Unconnected 1 0 Unconnected 1 -0.25 to +0.25 -0.375 to +0.375 -0.5 to +0.5 -0.75 to +0.75 -1.0 to +1.0 -1.5 to +1.5 N/A N/A Center Dither SPREAD-SPECTRUM MAGNITUDE SELECTED (%) SPREAD-SPECTRUM DITHER MODE SELECTED
Spread-Spectrum Disabled
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Spread-Spectrum Clock Generators MAX31C80/MAX31D80
DOWN DITHERED (MAX31D80) FREQUENCY
IF SMSEL0 = SMSEL1 = 0
fCLKOUT DITHER AMOUNT (-0.25% TO -3.0%) fCLKOUT - (0.25% TO 3%)
1 DITHER CYCLE RATE
TIME
Figure 1. Spread-Spectrum Frequency Modulation (Down Dithered)
CENTER DITHERED (MAX31C80) FREQUENCY IF SMSEL0 = SMSEL1 = 0 fCLKOUT + (0.25% TO 1.5%) fIN fCLKOUT - (0.25% TO 1.5%) 1 DITHER CYCLE RATE DITHER AMOUNT (0.25% TO 1.5%)
TIME
Figure 2. Spread-Spectrum Frequency Modulation (Center Dithered)
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Spread-Spectrum Clock Generators MAX31C80/MAX31D80
VCC VCC VALID
The MAX31C80/MAX31D80 can provide a variety of frequencies, which are available to users by ordering the device according to specifications listed in the Selector Guide table.
tPUP OUTPUT VALID
Factory Programmability
Email the factory at custom.oscillators@maxim-ic.com to obtain custom output frequencies for specific input frequencies not mentioned in the Selector Guide table.
XOUT
Applications Information
OUTPUT VALID
CLKOUT
To achieve best results, it is highly recommended that a decoupling capacitor be used on the IC power-supply pins. Typical values of decoupling capacitors are 0.01FF and 0.1FF. Use a high-quality, ceramic, surface-mount capacitor and mount it as close as possible to the VCC pins of the IC to minimize lead inductance.
Power-Supply Decoupling
Figure 3. Power-Up Timing
Selector Guide
PART MAX31C80T-UGQ+ MAX31C80T-002+ MAX31D80T-UGQ+ MAX31D80T-003+ INPUT FREQUENCY (MHz) 27 25 27 12 OUTPUT FREQUENCY (MHz) 100 63.05 100 12 DITHER RATE (kHz) 31.25 32.05 31.25 25 DITHER TYPE Center Center Down Down
+Denotes a lead(Pb)-free/RoHS-compliant package.
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 10 TDFN-EP PACKAGE CODE T1033+1 DOCUMENT NO. 21-0137
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Spread-Spectrum Clock Generators
Revision History
REVISION NUMBER 0 REVISION DATE 4/10 Initial release DESCRIPTION PAGES CHANGED --
MAX31C80/MAX31D80
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
(c)
9
2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.

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