Product Folder Sample & Buy Support & Community Tools & Software Technical Documents LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 LMK00304 3-GHz 4-Output Ultra-Low Additive Jitter Differential Clock Buffer/Level Translator 1 Features 2 Applications • • 1 • • • • • • • • 3:1 Input Multiplexer – Two Universal Inputs Operate up to 3.1 GHz and Accept LVPECL, LVDS, CML, SSTL, HSTL, HCSL, or Single-Ended Clocks – One Crystal Input Accepts a 10 to 40 MHz Crystal or Single-Ended Clock Two Banks with 2 Differential Outputs Each – LVPECL, LVDS, HCSL, or Hi-Z (Selectable) – LVPECL Additive Jitter with LMK03806 Clock Source at 156.25 MHz: – 20 fs RMS (10 kHz to 1 MHz) – 51 fs RMS (12 kHz to 20 MHz) High PSRR: -65 / -76 dBc (LVPECL/LVDS) at 156.25 MHz LVCMOS Output with Synchronous Enable Input Pin-Controlled Configuration VCC Core Supply: 3.3 V ± 5% 3 Independent VCCO Output Supplies: 3.3 V/2.5 V ± 5% Industrial Temperature Range: -40°C to +85°C 32-lead WQFN (5 mm × 5 mm) • • • Clock Distribution and Level Translation for ADCs, DACs, Multi-Gigabit Ethernet, XAUI, Fibre Channel, SATA/SAS, SONET/SDH, CPRI, HighFrequency Backplanes Switches, Routers, Line Cards, Timing Cards Servers, Computing, PCI Express (PCIe 3.0) Remote Radio Units and Baseband Units 3 Description The LMK00304 is a 3-GHz 4-output differential fanout buffer intended for high-frequency, low-jitter clock/data distribution and level translation. The input clock can be selected from two universal inputs or one crystal input. The selected input clock is distributed to two banks of 2 differential outputs and one LVCMOS output. The differential output banks can be mutually configured as LVPECL, LVDS, or HCSL drivers, or disabled. The LVCMOS output has a synchronous enable input for runt-pulse-free operation when enabled or disabled. The LMK00304 operates from a 3.3 V core supply and 3 independent 3.3 V/2.5 V output supplies. The LMK00304 provides high performance, versatility, and power efficiency, making it ideal for replacing fixed-output buffer devices while increasing timing margin in the system. Device Information(1) PART NUMBER PACKAGE LMK00304 WQFN (32) BODY SIZE (NOM) 5.00 mm x 5.00 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. 4 Functional Block Diagram CLKout_TYPE[1:0] CLKin_SEL[1:0] VCCOA VCCOB VCCOC LVPECL Output Swing (VOD) vs. Frequency 2 2 CLKoutA0 CLKoutA0* CLKin0 Universal Inputs (Differential/ Single-Ended) 1.0 VCCOA CLKoutA1 CLKoutA1* CLKin0* 0.9 Output Bank A (LVPECL, LVDS, HCSL, or Hi-Z) CLKin1 CLKin1* Crystal MUX VCCOB CLKoutB0 OSCin CLKoutB0* CLKoutB1 CLKoutB1* OSCout CLKout_TYPE[1:0] Output Bank B (LVPECL, LVDS, HCSL, or Hi-Z) REFout (LVCMOS) SYNC GND Vcco=2.5 V, Rterm=91 Vcco=3.3 V, Rterm=160 0.8 0.7 0.6 0.5 0.4 0.3 0.2 VCCOC REFout_EN OUTPUT SWING (V) VCC 0.1 0.0 100 1000 FREQUENCY (MHz) 10000 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Functional Block Diagram .................................... Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 7.1 7.2 7.3 7.4 7.5 7.6 1 1 1 1 2 4 6 Absolute Maximum Ratings ...................................... 6 ESD Ratings.............................................................. 6 Recommended Operating Conditions ...................... 6 Thermal Information .................................................. 6 Electrical Characteristics........................................... 7 Typical Characteristics ............................................ 14 8 Parameter Measurement Information ................ 18 9 Detailed Description ............................................ 19 8.1 Differential Voltage Measurement Terminology...... 18 9.1 Overview ................................................................. 19 9.2 Functional Block Diagram ....................................... 19 9.3 Feature Description................................................. 20 10 Application and Implementation........................ 22 10.1 Driving the Clock Inputs ........................................ 22 10.2 Crystal Interface .................................................... 23 10.3 Termination and Use of Clock Drivers .................. 24 11 Power Supply Recommendations ..................... 29 11.1 Power Supply Sequencing .................................... 11.2 Current Consumption and Power Dissipation Calculations.............................................................. 11.3 Power Supply Bypassing ...................................... 11.4 Thermal Management ........................................... 29 29 30 31 12 Device and Documentation Support ................. 33 12.1 12.2 12.3 12.4 12.5 Documentation Support ........................................ Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 33 33 33 33 33 13 Mechanical, Packaging, and Orderable Information ........................................................... 33 5 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision E (May 2013) to Revision F Page • Added "Ultra-Low Additive Jitter" to document title ................................................................................................................ 1 • Added, updated, or renamed the following sections: Specifications; Detailed Description; Application and Implementation; Power Supply Recommendations; Device and Documentation Support; Mechanical, Packaging, and Ordering Information ....................................................................................................................................................... 1 • Changed Cin (typ) from 1 pF to 4 pF (based on updated test method) in Electrical Characteristics: Crystal Interface ....... 8 • Added footnote for VI_SE parameter in the Electrical Characteristics table. .......................................................................... 8 • Added "Additive RMS Jitter, Integration Bandwidth 10 kHz to 20 MHz” parameter with 100 MHz and 156.25 MHz Test conditions, Typical values, Max values, and footnotes in Electrical Characteristics: LVPECL Outputs ....................... 9 • Added "Additive RMS Jitter, Integration Bandwidth 10 kHz to 20 MHz” parameter with 100 MHz and 156.25 MHz Test conditions, Typical values, Max values, and footnotes in Electrical Characteristics: LVDS Outputs .......................... 10 • Added new paragraph at end of Driving the Clock Inputs ................................................................................................... 22 • Changed "LMK00301" to "LMK00304" in Figure 27 and Figure 28 .................................................................................... 23 • Changed Cin = 4 pF (typ, based on updated test method) in Crystal Interface................................................................... 23 • Added POWER SUPPLY SEQUENCING ........................................................................................................................... 29 Changes from Revision D (February 2013) to Revision E Page • Changed VCM text to condition for VIH to VCM parameter group. ............................................................................................ 8 • Deleted VIH min value from Electrical Characteristics table. .................................................................................................. 8 • Deleted VIL max value from Electrical Characteristics table................................................................................................... 8 • Added VI_SE parameter and spec limits with corresponding table note to Electrical Characteristics Table. .......................... 8 • Changed third paragraph in Driving the Clock Inputs section to include CLKin* and LVCMOS text. Revised to better correspond with information in Electrical Characteristics Table. .......................................................................................... 22 • Changed bypass cap text to signal attenuation text of the fourth paragraph in Driving the Clock Inputs section. .............. 22 • Changed Single-Ended LVCMOS Input, DC Coupling with Common Mode Biasing image with revised graphic............... 23 • Added text to second paragraph of Termination for AC Coupled Differential Operation to explain graphic update to 2 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Differential LVDS Operation with AC Coupling to Receivers. .............................................................................................. 26 • Changed graphic for Differential LVDS Operation, AC Coupling, No Biasing by the Receiver and updated caption. ........ 26 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 3 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com 6 Pin Configuration and Functions CLKout_TYPE1 REFout_EN VCCOC REFout VCC CLKin1 CLKin1* NC 32-Pin WQFN Package RTV0032A Top View 32 31 30 29 28 27 26 25 GND 1 24 GND VCCOA 2 23 VCCOB CLKoutA0 3 22 CLKoutB0 CLKoutA0* 4 21 CLKoutB0* 20 VCCOB 19 CLKoutB1 Top Down View VCCOA 5 CLKoutA1 6 DAP 4 9 10 11 12 13 14 15 16 CLKin_SEL1 GND CLKin0* 17 CLKin0 8 CLKin_SEL0 GND OSCout CLKoutB1* OSCin 18 VCC 7 CLKout_TYPE0 CLKoutA1* Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Pin Functions (1) PIN NO. NAME TYPE DESCRIPTION DAP DAP GND Die Attach Pad. Connect to the PCB ground plane for heat dissipation. 1, 8 17, 24 GND GND Ground 2, 5 VCCOA PWR Power supply for Bank A Output buffers. VCCOA operates from 3.3 V or 2.5 V. The VCCOA pins are internally tied together. Bypass with a 0.1 uF lowESR capacitor placed very close to each Vcco pin. (2) 3, 4 CLKoutA0, CLKoutA0* O Differential clock output A0. Output type set by CLKout_TYPE pins. (1) (2) (3) 6, 7 CLKoutA1, CLKoutA1* O Differential clock output A1. Output type set by CLKout_TYPE pins. 9, 32 CLKout_TYPE0, CLKout_TYPE1 I Bank A and Bank B output buffer type selection pins 10, 28 Vcc PWR 11 OSCin I Input for crystal. Can also be driven by a XO, TCXO, or other external single-ended clock. 12 OSCout O Output for crystal. Leave OSCout floating if OSCin is driven by a singleended clock. 13, 16 CLKin_SEL0, CLKin_SEL1 I Clock input selection pins 14, 15 CLKin0, CLKin0* I Universal clock input 0 (differential/single-ended) 18, 19 CLKoutB1*, CLKoutB1 O Differential clock output B1. Output type set by CLKout_TYPE pins. 20, 23 VCCOB PWR 21, 22 CLKoutB0*, CLKoutB0 O Differential clock output B0. Output type set by CLKout_TYPE pins. 25 NC — Not connected internally. Pin may be floated, grounded, or otherwise tied to any potential within the Supply Voltage range stated in the Absolute Maximum Ratings . 26, 27 CLKin1*, CLKin1 I Universal clock input 1 (differential/single-ended) 29 REFout O LVCMOS reference output. Enable output by pulling REFout_EN pin high. 30 VCCOC PWR Power supply for REFout buffer. VCCOC operates from 3.3 V or 2.5 V. Bypass with a 0.1 uF low-ESR capacitor placed very close to each Vcco pin. (2) 31 REFout_EN I REFout enable input. Enable signal is internally synchronized to selected clock input. (3) (3) Power supply for Core and Input Buffer blocks. The Vcc supply operates from 3.3 V. Bypass with a 0.1 uF low-ESR capacitor placed very close to each Vcc pin. (3) Power supply for Bank B Output buffers. VCCOB operates from 3.3 V or 2.5 V. The VCCOB pins are internally tied together. Bypass with a 0.1 uF lowESR capacitor placed very close to each Vcco pin. See Absolute Maximum Ratings Any unused output pins should be left floating with minimum copper length (see note in Clock Outputs), or properly terminated if connected to a transmission line, or disabled/Hi-Z if possible. See Clock Outputs for output configuration and Termination and Use of Clock Drivers for output interface and termination techniques. The output supply voltages or pins (VCCOA, VCCOB, and VCCOC) will be called VCCO in general when no distinction is needed, or when the output supply can be inferred from the output bank/type. CMOS control input with internal pull-down resistor. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 5 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN MAX UNIT VCC, VCCO Supply Voltages -0.3 3.6 V VIN Input Voltage -0.3 (VCC + 0.3) V TSTG Storage Temperature Range -65 +150 °C TL Lead Temperature (solder 4 s) +260 °C TJ Junction Temperature +150 °C (1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 7.2 ESD Ratings VALUE Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 V(ESD) (1) (2) Electrostatic discharge (1) UNIT ±2000 Machine model (MM) ±150 Charged-device model (CDM), per JEDEC specification JESD22C101 (2) ±750 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Manufacturing with less than 500-V HBM is possible with the necessary precautions. Pins listed as ±2000 V may actually have higher performance. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Manufacturing with less than 250-V CDM is possible with the necessary precautions. Pins listed as ±750 V may actually have higher performance. 7.3 Recommended Operating Conditions TA Ambient Temperature Range TJ Junction Temperature VCC Core Supply Voltage Range VCCO Output Supply Voltage Range (1) (2) (1) (2) MIN TYP -40 25 MAX UNIT 85 °C 125 °C 3.15 3.3 3.45 V 3.3 – 5% 2.5 – 5% 3.3 2.5 3.3 + 5% 2.5 + 5% V The output supply voltages or pins (VCCOA, VCCOB, and VCCOC) will be called VCCO in general when no distinction is needed, or when the output supply can be inferred from the output bank/type. Vcco for any output bank should be less than or equal to Vcc (Vcco ≤ Vcc). 7.4 Thermal Information LMK00304 THERMAL METRIC (1) (1) (2) RTV0032A (WQFN) UNIT 32 PINS RθJA Junction-to-ambient thermal resistance 38.1 RθJC(top) (DAP) Junction-to-case (top) thermal resistance 7.2 (1) (2) 6 °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Specification assumes 5 thermal vias connect the die attach pad (DAP) to the embedded copper plane on the 4-layer JEDEC board. These vias play a key role in improving the thermal performance of the package. It is recommended that the maximum number of vias be used in the board layout. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 7.5 Electrical Characteristics Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN TYP MAX UNIT CLKinX selected 8.5 10.5 mA OSCin selected CURRENT CONSUMPTION (3) ICC_CORE Core Supply Current, All Outputs Disabled 10 13.5 mA ICC_PECL Additive Core Supply Current, LVPECL Banks Enabled 38 48 mA ICC_LVDS Additive Core Supply Current, LVDS Banks Enabled 43 52 mA ICC_HCSL Additive Core Supply Current, HCSL Banks Enabled 50 58.5 mA ICC_CMOS Additive Core Supply Current, LVCMOS Output Enabled 3.5 5.5 mA ICCO_PECL Additive Output Supply Current, LVPECL Banks Enabled 135 163 mA ICCO_LVDS Additive Output Supply Current, LVDS Banks Enabled 25 34.5 mA ICCO_HCSL Additive Output Supply Current, HCSL Banks Enabled Includes Output Bank Bias and Load Currents for both banks, RT = 50 Ω on all outputs 65 81.5 mA Additive Output Supply Current, LVCMOS Output Enabled Vcco = 3.3 V ± 5% 9 10 mA ICCO_CMOS 200 MHz, CL = 5 pF Vcco = 2.5 V ± 5% 7 8 mA Includes Output Bank Bias and Load Currents for both banks, RT = 50 Ω to Vcco - 2V on all outputs POWER SUPPLY RIPPLE REJECTION (PSRR) PSRRPECL Ripple-Induced Phase Spur Level Differential LVPECL Output (4) PSRRLVDS Ripple-Induced Phase Spur Level Differential LVDS Output (4) PSRRHCSL Ripple-Induced Phase Spur Level Differential HCSL Output (4) 100 kHz, 100 mVpp Ripple Injected on Vcco, Vcco = 2.5 V 156.25 MHz -65 312.5 MHz -63 156.25 MHz -76 312.5 MHz -74 156.25 MHz -72 312.5 MHz -63 dBc dBc dBc CMOS CONTROL INPUTS (CLKin_SELn, CLKout_TYPEn, REFout_EN) VIH High-Level Input Voltage 1.6 Vcc VIL Low-Level Input Voltage GND 0.4 V IIH High-Level Input Current VIH = Vcc, Internal pull-down resistor 50 µA IIL Low-Level Input Current (1) (2) (3) (4) VIL = 0 V, Internal pull-down resistor -5 0.1 V µA The output supply voltages or pins (VCCOA, VCCOB, and VCCOC) will be called VCCO in general when no distinction is needed, or when the output supply can be inferred from the output bank/type. The Electrical Characteristics tables list ensured specifications under the listed Recommended Operating Conditions except as otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not ensured. See Power Supply Recommendations for more information on current consumption and power dissipation calculations. Power supply ripple rejection, or PSRR, is defined as the single-sideband phase spur level (in dBc) modulated onto the clock output when a single-tone sinusoidal signal (ripple) is injected onto the Vcco supply. Assuming no amplitude modulation effects and small index modulation, the peak-to-peak deterministic jitter (DJ) can be calculated using the measured single-sideband phase spur level (PSRR) as follows: DJ (ps pk-pk) = [ (2 * 10(PSRR / 20)) / (π * fCLK) ] * 1E12 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 7 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Electrical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN TYP MAX UNIT 3.1 GHz Vcc V CLOCK INPUTS (CLKin0/CLKin0*, CLKin1/CLKin1*) fCLKin Input Frequency Range (5) VIHD Differential Input High Voltage VILD Differential Input Low Voltage VID Differential Input Voltage Swing (6) VCMD Differential Input Common Mode Voltage VIH Single-Ended Input High Voltage VIL Single-Ended Input Low Voltage VI_SE Single-Ended Input Voltage Swing (7) (8) VCM Single-Ended Input Common Mode Voltage ISOMUX Functional up to 3.1 GHz Output frequency range and timing specified per output type (refer to LVPECL, LVDS, HCSL, LVCMOS output specifications) CLKin driven differentially DC GND V 0.15 1.3 VID = 150 mV 0.25 Vcc - 1.2 VID = 350 mV 0.25 Vcc - 1.1 VID = 800 mV 0.25 Vcc - 0.9 Vcc CLKinX driven single-ended (AC or DC coupled), CLKinX* AC coupled to GND or externally biased within VCM range Mux Isolation, CLKin0 to fOFFSET > 50 kHz, CLKin1 PCLKinX = 0 dBm GND V V V V 0.3 2 0.25 Vcc - 1.2 fCLKin0 = 100 MHz -84 fCLKin0 = 200 MHz -82 fCLKin0 = 500 MHz -71 fCLKin0 = 1000 MHz -65 Vpp V dBc CRYSTAL INTERFACE (OSCin, OSCout) FCLK External Clock Frequency Range (5) OSCin driven single-ended, OSCout floating FXTAL Crystal Frequency Range Fundamental mode crystal ESR ≤ 200 Ω (10 to 30 MHz) ESR ≤ 125 Ω (30 to 40 MHz) CIN OSCin Input Capacitance (5) (6) (7) (8) (9) 8 (9) 10 4 250 MHz 40 MHz pF Specification is ensured by characterization and is not tested in production. See Differential Voltage Measurement Terminology for definition of VID and VOD voltages. Parameter is specified by design, not tested in production. For clock input frequency ≥ 100 MHz, CLKinX can be driven with single-ended (LVCMOS) input swing up to 3.3 Vpp. For clock input frequency < 100 MHz, the single-ended input swing should be limited to 2 Vpp max to prevent input saturation (refer to Driving the Clock Inputs for interfacing 2.5 V/3.3 V LVCMOS clock input < 100 MHz to CLKinX). The ESR requirements stated must be met to ensure that the oscillator circuitry has no startup issues. However, lower ESR values for the crystal may be necessary to stay below the maximum power dissipation (drive level) specification of the crystal. Refer to Crystal Interface for crystal drive level considerations. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Electrical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN TYP Vcco = 3.3 V ± 5%, RT = 160 Ω to GND 1.0 1.2 Vcco = 2.5 V ± 5%, RT = 91 Ω to GND 0.75 1.0 Vcco = 3.3 V ± 5%, RT = 160 Ω to GND 1.5 3.1 Vcco = 2.5 V ± 5%, RT = 91 Ω to GND 1.5 2.3 MAX UNIT LVPECL OUTPUTS (CLKoutAn/CLKoutAn*, CLKoutBn/CLKoutBn*) fCLKout_FS fCLKout_RS JitterADD JitterADD JitterADD Noise Floor DUTY Maximum Output Frequency Full VOD Swing (5) (10) VOD ≥ 600 mV, RL = 100 Ω differential Maximum Output Frequency Reduced VOD Swing (5) (10) VOD ≥ 400 mV, RL = 100 Ω differential Additive RMS Jitter, Integration Bandwidth 10 kHz to 20 MHz (5) (11) (12) Vcco = 2.5 V ± 5%: RT = 91 Ω to GND, Vcco = 3.3 V ± 5%: RT = 160 to GND, RL = 100 Ω differential Additive RMS Jitter Integration Bandwidth 1 MHz to 20 MHz (11) Additive RMS Jitter with LVPECL clock source from LMK03806 (11) (13) Noise Floor fOFFSET ≥ 10 MHz (14) (15) Duty Cycle (5) VOH Output High Voltage VOL Output Low Voltage VOD Vcco = 3.3 V, RT = 160 Ω to GND, RL = 100 Ω differential Output Voltage Swing Vcco = 3.3 V, RT = 160 Ω to GND, RL = 100 Ω differential Vcco = 3.3 V, RT = 160 Ω to GND, RL = 100 Ω differential GHz GHz CLKin: 100 MHz, Slew rate ≥ 3 V/ns 77 98 CLKin: 156.25 MHz, Slew rate ≥ 3 V/ns 54 78 fs CLKin: 100 MHz, Slew rate ≥ 3 V/ns 59 CLKin: 156.25 MHz, Slew rate ≥ 2.7 V/ns 64 CLKin: 625 MHz, Slew rate ≥ 3 V/ns 30 fs CLKin: 156.25 MHz, JSOURCE = 190 fs RMS (10 kHz to 1 MHz) 20 CLKin: 156.25 MHz, JSOURCE = 195 fs RMS (12 kHz to 20 MHz) 51 fs CLKin: 100 MHz, Slew rate ≥ 3 V/ns -162.5 CLKin: 156.25 MHz, Slew rate ≥ 2.7 V/ns -158.1 CLKin: 625 MHz, Slew rate ≥ 3 V/ns -154.4 50% input clock duty cycle TA = 25 °C, DC Measurement, RT = 50 Ω to Vcco - 2 V (6) 45% dBc/Hz 55% Vcco 1.2 Vcco 0.9 Vcco 0.7 V Vcco 2.0 Vcco 1.75 Vcco 1.5 V 600 830 1000 mV (10) See Typical Characteristics for output operation over frequency. (11) For the 100 MHz and 156.25 MHz clock input conditions, Additive RMS Jitter (JADD) is calculated using Method #1: JADD = SQRT(JOUT2 - JSOURCE2), where JOUT is the total RMS jitter measured at the output driver and JSOURCE is the RMS jitter of the clock source applied to CLKin. For the 625 MHz clock input condition, Additive RMS Jitter is approximated using Method #2: JADD = SQRT(2*10dBc/10) / (2*π*fCLK), where dBc is the phase noise power of the Output Noise Floor integrated from 1 to 20 MHz bandwidth. The phase noise power can be calculated as: dBc = Noise Floor + 10*log10(20 MHz - 1 MHz). The additive RMS jitter was approximated for 625 MHz using Method #2 because the RMS jitter of the clock source was not sufficiently low enough to allow practical use of Method #1. Refer to the “Noise Floor vs. CLKin Slew Rate” and “RMS Jitter vs. CLKin Slew Rate” plots in Typical Characteristics. (12) 100 MHz and 156.25 MHz input source from Rohde & Schwarz SMA100A Low-Noise Signal Generator and Sine-to-Square-wave Conversion block. (13) 156.25 MHz LVPECL clock source from LMK03806 with 20 MHz crystal reference (crystal part number: ECS-200-20-30BU-DU). JSOURCE = 190 fs RMS (10 kHz to 1 MHz) and 195 fs RMS (12 kHz to 20 MHz). Refer to the LMK03806 datasheet for more information. (14) The noise floor of the output buffer is measured as the far-out phase noise of the buffer. Typically this offset is ≥ 10 MHz, but for lower frequencies this measurement offset can be as low as 5 MHz due to measurement equipment limitations. (15) Phase noise floor will degrade as the clock input slew rate is reduced. Compared to a single-ended clock, a differential clock input (LVPECL, LVDS) will be less susceptible to degradation in noise floor at lower slew rates due to its common mode noise rejection. However, it is recommended to use the highest possible input slew rate for differential clocks to achieve optimal noise floor performance at the device outputs. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 9 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Electrical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN Output Rise Time 20% to 80% (7) tR RT = 160 Ω to GND, Uniform transmission line up to 10 in. with 50-Ω characteristic impedance, RL = Output Fall Time 80% to 100 Ω differential CL ≤ 5 pF (7) 20% tF TYP MAX UNIT 175 300 ps 175 300 ps LVDS OUTPUTS (CLKoutAn/CLKoutAn*, CLKoutBn/CLKoutBn*) fCLKout_FS Maximum Output Frequency Full VOD Swing (5) (10) VOD ≥ 250 mV, RL = 100 Ω differential 1.0 1.6 GHz fCLKout_RS Maximum Output Frequency Reduced VOD Swing (5) (10) VOD ≥ 200 mV, RL = 100 Ω differential 1.5 2.1 GHz JitterADD Additive RMS Jitter, Integration Bandwidth 10 kHz to 20 MHz RL = 100 Ω differential (5) (11) (12) JitterADD Noise Floor Additive RMS Jitter Integration Bandwidth 1 MHz to 20 MHz (11) Noise Floor fOFFSET ≥ 10 MHz (14) (15) DUTY Duty Cycle (5) VOD Output Voltage Swing (6) ΔVOD Change in Magnitude of VOD for Complementary Output States VOS Output Offset Voltage ΔVOS Change in Magnitude of VOS for Complementary Output States ISA ISB Output Short Circuit Current Single Ended ISAB Output Short Circuit Current Differential tR Output Rise Time 20% to 80% (7) tF Output Fall Time 80% to 20% (7) 10 Vcco = 3.3 V, RL = 100 Ω differential Vcco = 3.3 V, RL = 100 Ω differential CLKin: 100 MHz, Slew rate ≥ 3 V/ns 94 115 CLKin: 156.25 MHz, Slew rate ≥ 3 V/ns 70 90 CLKin: 100 MHz, Slew rate ≥ 3 V/ns 89 CLKin: 156.25 MHz, Slew rate ≥ 2.7 V/ns 77 CLKin: 625 MHz, Slew rate ≥ 3 V/ns 37 CLKin: 100 MHz, Slew rate ≥ 3 V/ns -159.5 CLKin: 156.25 MHz, Slew rate ≥ 2.7 V/ns -157.0 CLKin: 625 MHz, Slew rate ≥ 3 V/ns -152.7 fs 50% input clock duty cycle 45% 250 fs dBc/Hz 55% 400 450 mV 50 mV -50 TA = 25 °C, DC Measurement, RL = 100 Ω differential 1.125 1.25 1.375 V -35 35 mV TA = 25 °C, Single ended outputs shorted to GND -24 24 mA Complementary outputs tied together -12 12 mA Uniform transmission line up to 10 inches with 50Ω characteristic impedance, RL = 100 Ω differential, CL ≤ 5 pF Submit Documentation Feedback 175 300 ps 175 300 ps Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Electrical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN TYP MAX UNIT 400 MHz 0.15 ps HCSL OUTPUTS (CLKoutAn/CLKoutAn*, CLKoutBn/CLKoutBn*) fCLKout Output Frequency Range (5) RL = 50 Ω to GND, CL ≤ 5 pF JitterADD_PCIe Additive RMS Phase Jitter for PCIe 3.0 (5) PCIe Gen 3, PLL BW = 2–5 MHz, CDR = 10 MHz JitterADD Additive RMS Jitter Integration Bandwidth 1 MHz to 20 MHz (11) Vcco = 3.3 V, RT = 50 Ω to GND Noise Floor fOFFSET ≥ 10 MHz (14) (15) Vcco = 3.3 V, RT = 50 Ω to GND DUTY Duty Cycle (5) 50% input clock duty cycle VOH Output High Voltage VOL Output Low Voltage VCROSS Absolute Crossing Voltage (5) (16) Noise Floor ΔVCROSS Total Variation of VCROSS (5) (16) tR Output Rise Time 20% to 80% (7) (16) tF Output Fall Time 80% to 20% (7) (16) DC CLKin: 100 MHz, Slew rate ≥ 0.6 V/ns 0.03 CLKin: 100 MHz, Slew rate ≥ 3 V/ns 77 CLKin: 156.25 MHz, Slew rate ≥ 2.7 V/ns 86 fs CLKin: 100 MHz, Slew rate ≥ 3 V/ns -161.3 CLKin: 156.25 MHz, Slew rate ≥ 2.7 V/ns -156.3 TA = 25 °C, DC Measurement, RT = 50 Ω to GND dBc/Hz 45% 55% 520 810 920 mV -150 0.5 150 mV 250 350 460 mV 140 mV 300 500 ps 300 500 ps RL = 50 Ω to GND, CL ≤ 5 pF 250 MHz, Unifrom transmission line up to 10 inches with 50-Ω characteristic impedance, RL = 50 Ω to GND, CL ≤ 5 pF (16) AC timing parameters for HCSL or CMOS are dependent on output capacitive loading. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 11 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Electrical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN TYP MAX UNIT 250 MHz LVCMOS OUTPUT (REFout) fCLKout Output Frequency Range (5) CL ≤ 5 pF JitterADD Additive RMS Jitter Integration Bandwidth 1 MHz to 20 MHz (11) Vcco = 3.3 V, CL ≤ 5 pF 100 MHz, Input Slew rate ≥ 3 V/ns 95 Noise Floor Noise Floor fOFFSET ≥ 10 MHz (14) (15) Vcco = 3.3 V, CL ≤ 5 pF 100 MHz, Input Slew rate ≥ 3 V/ns -159.3 DUTY Duty Cycle (5) 50% input clock duty cycle VOH Output High Voltage VOL Output Low Voltage IOH DC tR Output Rise Time 20% to 80% (7) (16) tF Output Fall Time 80% to 20% (7) (16) tEN Output Enable Time (17) tDIS Output Disable Time (17) 55% V 0.1 Vo = Vcco / 2 Output Low Current (Sink) dBc/Hz Vcco 0.1 1 mA load Output High Current (Source) IOL 45% fs Vcco = 3.3 V 28 Vcco = 2.5 V 20 Vcco = 3.3 V 28 Vcco = 2.5 V 20 250 MHz, Uniform transmission line up to 10 inches with 50-Ω characteristic impedance, RL = 50 Ω to GND, CL ≤ 5 pF CL ≤ 5 pF V mA mA 225 400 ps 225 400 ps 3 cycles 3 cycles (17) Output Enable Time is the number of input clock cycles it takes for the output to be enabled after REFout_EN is pulled high. Similarly, Output Disable Time is the number of input clock cycles it takes for the output to be disabled after REFout_EN is pulled low. The REFout_EN signal should have an edge transition much faster than that of the input clock period for accurate measurement. 12 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Electrical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V ± 5%, Vcco = 3.3 V ± 5%, 2.5 V ± 5%, -40 °C ≤ TA ≤ 85 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Typical values represent most likely parametric norms at Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, and at the Recommended Operation Conditions at the time of product characterization and are not ensured. (1) (2) TEST CONDITIONS MIN TYP MAX UNIT PROPAGATION DELAY and OUTPUT SKEW tPD_PECL Propagation Delay CLKin-to-LVPECL (7) RT = 160 Ω to GND, RL = 100 Ω differential, CL ≤ 5 pF 180 360 540 ps tPD_LVDS Propagation Delay CLKin-to-LVDS (7) RL = 100 Ω differential, CL ≤ 5 pF 200 400 600 ps tPD_HCSL Propagation Delay CLKin-to-HCSL (7) (16) RT = 50 Ω to GND, CL ≤ 5 pF 295 590 885 ps tPD_CMOS Propagation Delay CL ≤ 5 pF CLKin-to-LVCMOS (7) (16) Vcco = 3.3 V 900 1475 2300 Vcco = 2.5 V 1000 1550 2700 tSK(O) Output Skew LVPECL/LVDS/HCSL 30 50 ps 80 120 ps tSK(PP) (5) (16) (18) Part-to-Part Output Skew LVPECL/LVDS/HCSL Skew specified between any two CLKouts with the same buffer type. Load conditions per output type are the same as propagation delay specifications. ps (7) (16) (18) (18) Output skew is the propagation delay difference between any two outputs with identical output buffer type and equal loading while operating at the same supply voltage and temperature conditions. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 13 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com 7.6 Typical Characteristics Unless otherwise specified: Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Consult Table 1 at the end of the Typical Characteristics section for graph notes. 1.0 0.45 Vcco=2.5 V, Rterm=91 Vcco=3.3 V, Rterm=160 0.40 0.8 OUTPUT SWING (V) OUTPUT SWING (V) 0.9 0.7 0.6 0.5 0.4 0.3 0.20 0.15 0.10 0.05 0.00 1000 FREQUENCY (MHz) 10000 Figure 1. LVPECL Output Swing (VOD) vs. Frequency 100 0.4 0.6 0.3 0.4 0.2 0.2 0.0 -0.2 -0.4 -0.6 0.1 0.0 -0.1 -0.2 -0.4 2.5 5.0 TIME (ns) 7.5 10.0 Figure 3. LVPECL Output Swing @ 156.25 MHz 0.0 0.3 0.3 OUTPUT SWING (V) 0.4 0.2 0.1 0.0 -0.1 -0.2 2.5 5.0 TIME (ns) 7.5 10.0 Figure 4. LVDS Output Swing @ 156.25 MHz 0.4 -0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 0.00 10000 -0.3 -0.8 0.0 1000 FREQUENCY (MHz) Figure 2. LVDS Output Swing (VOD) vs. Frequency 0.8 OUTPUT SWING (V) OUTPUT SWING (V) 0.25 0.1 100 OUTPUT SWING (V) 0.30 0.2 0.0 -0.4 0.25 0.50 TIME (ns) 0.75 1.00 Figure 5. LVPECL Output Swing @ 1.5 GHz 14 0.35 Submit Documentation Feedback 0.00 0.25 0.50 TIME (ns) 0.75 1.00 Figure 6. LVDS Output Swing @ 1.5 GHz Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Typical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Consult Table 1 at the end of the Typical Characteristics section for graph notes. 1.0 1.00 OUTPUT SWING (V) OUTPUT SWING (V) 0.8 0.6 0.4 0.2 0.0 1 2 3 TIME (ns) 4 LVPECL LVDS HCSL LVCMOS CLKin Source -135 Fclk=100 MHz Foffset=20 MHz NOISE FLOOR (dBc/Hz) NOISE FLOOR (dBc/Hz) -0.50 -155 -160 -165 1 2 3 4 TIME (ns) 5 6 Figure 8. LVCMOS Output Swing @ 250 MHz -170 -140 LVPECL LVDS HCSL CLKin Source Fclk=156.25 MHz Foffset=20 MHz -145 -150 -155 -160 -165 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT SLEW RATE (V/ns) Figure 9. Noise Floor vs. CLKin Slew Rate @ 100 MHz LVPECL LVDS CLKin Source 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT SLEW RATE (V/ns) Figure 10. Noise Floor vs. CLKin Slew Rate @ 156.25 MHz 400 Fclk=625 MHz Foffset=20 MHz 350 RMS JITTER (fs) NOISE FLOOR (dBc/Hz) 0.00 -0.25 0 -150 -140 0.25 5 Figure 7. HCSL Output Swing @ 250 MHz -135 0.50 -1.00 0 -145 load load -0.75 -0.2 -140 Vcco=3.3 V, AC coupled, 50 Vcco=2.5 V, AC coupled, 50 0.75 -145 -150 -155 300 LVPECL LVDS HCSL LVCMOS CLKin Source Fclk=100 MHz Int. BW=1-20 MHz 250 200 150 100 -160 50 -165 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT SLEW RATE (V/ns) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT SLEW RATE (V/ns) See Note 1 in Graph Notes table Figure 11. Noise Floor vs. CLKin Slew Rate @ 625 MHz Figure 12. RMS Jitter vs. CLKin Slew Rate @ 100 MHz Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 15 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Typical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Consult Table 1 at the end of the Typical Characteristics section for graph notes. 450 RMS JITTER (fs) 400 LVPECL LVDS HCSL CLKin Source 200 Fclk=156.25 MHz Int. BW=1-20 MHz LVPECL LVDS CLKin Source 175 RMS JITTER (fs) 500 350 300 250 200 150 Fclk=625 MHz Int. BW=1-20 MHz 150 125 100 75 50 100 50 25 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT SLEW RATE (V/ns) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT SLEW RATE (V/ns) See Note 1 in Graph Notes table -50 LVPECL LVDS HCSL -55 Fclk=156.25 MHz Vcco Ripple=100 mVpp -60 -65 -70 -75 -80 -85 -90 .1 1 RIPPLE FREQUENCY (MHz) 10 Figure 15. PSRR vs. Ripple Frequency @ 156.25 MHz 750 650 LVPECL (0.35 ps/°C) LVDS (0.35 ps/°C) HCSL (0.35 ps/°C) LVCMOS (2.2 ps/°C) Right Y-axis plot 1850 1750 1650 450 1550 350 1450 -50 1350 -25 0 25 50 75 TEMPERATURE (°C) LVPECL LVDS HCSL -55 Fclk=312.5 MHz Vcco Ripple=100 mVpp -60 -65 -70 -75 -80 -85 -90 .1 1 RIPPLE FREQUENCY (MHz) 10 Figure 16. PSRR vs. Ripple Frequency @ 312.5 MHz 1950 550 250 -50 REFout PROPAGATION DELAY (ps) CLKout PROPAGATION DELAY (ps) 850 Figure 14. RMS Jitter vs. CLKin Slew Rate @ 625 MHz RIPPLE INDUCED SPUR LEVEL (dBc) RIPPLE INDUCED SPUR LEVEL (dBc) Figure 13. RMS Jitter vs. CLKin Slew Rate @ 156.25 MHz 100 See Note 1 in Graph Notes table Figure 17. Propagation Delay vs. Temperature 16 Figure 18. LVPECL Phase Noise @ 100 MHz Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Typical Characteristics (continued) Unless otherwise specified: Vcc = 3.3 V, Vcco = 3.3 V, TA = 25 °C, CLKin driven differentially, input slew rate ≥ 3 V/ns. Consult Table 1 at the end of the Typical Characteristics section for graph notes. See Note 1 in Graph Notes table See Note 1 in Graph Notes table 200 Figure 20. HCSL Phase Noise @ 100 MHz -60 20 MHz Crystal 40 MHz Crystal 175 PHASE NOISE (dBc/Hz) CRYSTAL POWER DISSIPATION ( W) Figure 19. LVDS Phase Noise @ 100 MHz 150 125 100 75 50 25 0 20 MHz Crystal, Rlim = 1.5 k 40 MHz Crystal, Rlim = 1.0 k -80 -100 -120 -140 -160 -180 0 500 1k 1.5k 2k 2.5k 3k 3.5k 4k RLIM( ) 10 See Notes 2 and 3 in Graph Notes table 100 1k 10k 100k 1M OFFSET FREQUENCY (Hz) 10M See Notes 2 and 3 in Graph Notes table Figure 21. Crystal Power Dissipation vs. RLIM Figure 22. LVDS Phase Noise in Crystal Mode Table 1. Graph Notes NOTE (1) The typical RMS jitter values in the plots show the total output RMS jitter (JOUT) for each output buffer type and the source clock RMS jitter (JSOURCE). From these values, the Additive RMS Jitter can be calculated as: JADD = SQRT(JOUT2 - JSOURCE2). (2) 20 MHz crystal characteristics: Abracon ABL series, AT cut, CL = 18 pF , C0 = 4.4 pF measured (7 pF max), ESR = 8.5 Ω measured (40 Ω max), and Drive Level = 1 mW max (100 µW typical). (3) 40 MHz crystal characteristics: Abracon ABLS2 series, AT cut, CL = 18 pF , C0 = 5 pF measured (7 pF max), ESR = 5 Ω measured (40 Ω max), and Drive Level = 1 mW max (100 µW typical). Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 17 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com 8 Parameter Measurement Information 8.1 Differential Voltage Measurement Terminology The differential voltage of a differential signal can be described by two different definitions causing confusion when reading datasheets or communicating with other engineers. This section will address the measurement and description of a differential signal so that the reader will be able to understand and discern between the two different definitions when used. The first definition used to describe a differential signal is the absolute value of the voltage potential between the inverting and non-inverting signal. The symbol for this first measurement is typically VID or VOD depending on if an input or output voltage is being described. The second definition used to describe a differential signal is to measure the potential of the non-inverting signal with respect to the inverting signal. The symbol for this second measurement is VSS and is a calculated parameter. Nowhere in the IC does this signal exist with respect to ground, it only exists in reference to its differential pair. VSS can be measured directly by oscilloscopes with floating references, otherwise this value can be calculated as twice the value of VOD as described in the first description. Figure 23 illustrates the two different definitions side-by-side for inputs and Figure 24 illustrates the two different definitions side-by-side for outputs. The VID (or VOD) definition show the DC levels, VIH and VOL (or VOH and VOL), that the non-inverting and inverting signals toggle between with respect to ground. VSS input and output definitions show that if the inverting signal is considered the voltage potential reference, the non-inverting signal voltage potential is now increasing and decreasing above and below the non-inverting reference. Thus the peakto-peak voltage of the differential signal can be measured. VID and VOD are often defined as volts (V) and VSS is often defined as volts peak-to-peak (VPP). VID Definition VSS Definition for Input Non-Inverting Clock VIH VCM VSS VID VIL Inverting Clock VSS = 2· VID VID = | VIH ± VIL | GND Figure 23. Two Different Definitions for Differential Input Signals VOD Definition VSS Definition for Output Non-Inverting Clock VOH VOS VOL VSS VOD Inverting Clock VOD = | VOH - VOL | VSS = 2· VOD GND Figure 24. Two Different Definitions for Differential Output Signals Refer to Application Note AN-912 (SNLA036), Common Data Transmission Parameters and their Definitions, for more information. 18 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 9 Detailed Description 9.1 Overview The LMK00304 is a 4-output differential clock fanout buffer with low additive jitter that can operate up to 3.1 GHz. It features a 3:1 input multiplexer with an optional crystal oscillator input, two banks of 2 differential outputs with multi-mode buffers (LVPECL, LVDS, HCSL, or Hi-Z), one LVCMOS output, and 3 independent output buffer supplies. The input selection and output buffer modes are controlled via pin strapping. The device is offered in a 32-pin WQFN package and leverages much of the high-speed, low-noise circuit design employed in the LMK04800 family of clock conditioners. 9.2 Functional Block Diagram VCC CLKout_TYPE[1:0] CLKin_SEL[1:0] VCCOA VCCOB VCCOC 2 2 VCCOA CLKoutA0 CLKoutA0* CLKin0 Universal Inputs (Differential/ Single-Ended) CLKoutA1 CLKoutA1* CLKin0* Output Bank A (LVPECL, LVDS, HCSL, or Hi-Z) CLKin1 MUX CLKin1* Crystal VCCOB CLKoutB0 OSCin CLKoutB0* CLKoutB1 CLKoutB1* OSCout CLKout_TYPE[1:0] Output Bank B (LVPECL, LVDS, HCSL, or Hi-Z) VCCOC REFout_EN REFout (LVCMOS) SYNC GND Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 19 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com 9.3 Feature Description 9.3.1 VCC and VCCO Power Supplies The LMK00304 has separate 3.3 V core supply (VCC) and 3 independent 3.3 V/2.5 V output power supplies (VCCOA, VCCOB, VCCOC). Output supply operation at 2.5 V enables lower power consumption and output-level compatibility with 2.5 V receiver devices. The output levels for LVPECL (VOH, VOL) and LVCMOS (VOH) are referenced to its respective Vcco supply, while the output levels for LVDS and HCSL are relatively constant over the specified Vcco range. Refer to Power Supply Recommendations for additional supply related considerations, such as power dissipation, power supply bypassing, and power supply ripple rejection (PSRR). NOTE Care should be taken to ensure the Vcco voltages do not exceed the Vcc voltage to prevent turning-on the internal ESD protection circuitry. 9.3.2 Clock Inputs The input clock can be selected from CLKin0/CLKin0*, CLKin1/CLKin1*, or OSCin. Clock input selection is controlled using the CLKin_SEL[1:0] inputs as shown in Table 2. Refer to Driving the Clock Inputs for clock input requirements. When CLKin0 or CLKin1 is selected, the crystal circuit is powered down. When OSCin is selected, the crystal oscillator circuit will start-up and its clock will be distributed to all outputs. Refer to Crystal Interface for more information. Alternatively, OSCin may be driven by a single-ended clock (up to 250 MHz) instead of a crystal. Table 2. Input Selection CLKin_SEL1 CLKin_SEL0 SELECTED INPUT 0 0 CLKin0, CLKin0* 0 1 CLKin1, CLKin1* 1 X OSCin Table 3 shows the output logic state vs. input state when either CLKin0/CLKin0* or CLKin1/CLKin1* is selected. When OSCin is selected, the output state will be an inverted copy of the OSCin input state. Table 3. CLKin Input vs. Output States 20 STATE of SELECTED CLKin STATE of ENABLED OUTPUTS CLKinX and CLKinX* inputs floating Logic low CLKinX and CLKinX* inputs shorted together Logic low CLKin logic low Logic low CLKin logic high Logic high Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 9.3.3 Clock Outputs The differential output buffer type for both Bank A and B outputs are configured using the CLKout_TYPE[1:0] as shown in Table 4. For applications where all differential outputs are not needed, any unused output pin should be left floating with a minimum copper length (see note below) to minimize capacitance and potential coupling and reduce power consumption. If all differential outputs are not used, it is recommended to disable (Hi-Z) the banks to reduce power. Refer to Termination and Use of Clock Drivers for more information on output interface and termination techniques. NOTE For best soldering practices, the minimum trace length for any unused pin should extend to include the pin solder mask. This way during reflow, the solder has the same copper area as connected pins. This allows for good, uniform fillet solder joints helping to keep the IC level during reflow. Table 4. Differential Output Buffer Type Selection CLKout_ TYPE1 CLKout_ TYPE0 CLKoutX BUFFER TYPE (BANK A and B) 0 0 LVPECL 0 1 LVDS 1 0 HCSL 1 1 Disabled (Hi-Z) 9.3.3.1 Reference Output The reference output (REFout) provides a LVCMOS copy of the selected input clock. The LVCMOS output high level is referenced to the Vcco voltage. REFout can be enabled or disabled using the enable input pin, REFout_EN, as shown in Table 5. Table 5. Reference Output Enable REFout_EN REFout STATE 0 Disabled (Hi-Z) 1 Enabled The REFout_EN input is internally synchronized with the selected input clock by the SYNC block. This synchronizing function prevents glitches and runt pulses from occurring on the REFout clock when enabled or disabled. REFout will be enabled within 3 cycles (tEN) of the input clock after REFout_EN is toggled high. REFout will be disabled within 3 cycles (tDIS) of the input clock after REFout_EN is toggled low. When REFout is disabled, the use of a resistive loading can be used to set the output to a predetermined level. For example, if REFout is configured with a 1 kΩ load to ground, then the output will be pulled to low when disabled. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 21 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com 10 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 10.1 Driving the Clock Inputs The LMK00304 has two universal inputs (CLKin0/CLKin0* and CLKin1/CLKin1*) that can accept DC-coupled 3.3V/2.5V LVPECL, LVDS, CML, SSTL, and other differential and single-ended signals that meet the input requirements specified in Electrical Characteristics . The device can accept a wide range of signals due to its wide input common mode voltage range (VCM ) and input voltage swing (VID) / dynamic range. For 50% duty cycle and DC-balanced signals, AC coupling may also be employed to shift the input signal to within the VCM range. Refer to Termination and Use of Clock Drivers for signal interfacing and termination techniques. To achieve the best possible phase noise and jitter performance, it is mandatory for the input to have high slew rate of 3 V/ns (differential) or higher. Driving the input with a lower slew rate will degrade the noise floor and jitter. For this reason, a differential signal input is recommended over single-ended because it typically provides higher slew rate and common-mode-rejection. Refer to the “Noise Floor vs. CLKin Slew Rate” and “RMS Jitter vs. CLKin Slew Rate” plots in Typical Characteristics. While it is recommended to drive the CLKin/CLKin* pair with a differential signal input, it is possible to drive it with a single-ended clock provided it conforms to the Single-Ended Input specifications for CLKin pins listed in the Electrical Characteristics. For large single-ended input signals, such as 3.3V or 2.5V LVCMOS, a 50 Ω load resistor should be placed near the input for signal attenuation to prevent input overdrive as well as for line termination to minimize reflections. Again, the single-ended input slew rate should be as high as possible to minimize performance degradation. The CLKin input has an internal bias voltage of about 1.4 V, so the input can be AC coupled as shown in Figure 25. The output impedance of the LVCMOS driver plus Rs should be close to 50 Ω to match the characteristic impedance of the transmission line and load termination. RS 0.1 PF 0.1 PF 50: Trace 50: CMOS Driver LMK Input 0.1 PF Figure 25. Single-Ended LVCMOS Input, AC Coupling A single-ended clock may also be DC coupled to CLKinX as shown in Figure 26. A 50-Ω load resistor should be placed near the CLKin input for signal attenuation and line termination. Because half of the single-ended swing of the driver (VO,PP / 2) drives CLKinX, CLKinX* should be externally biased to the midpoint voltage of the attenuated input swing ((VO,PP / 2) × 0.5). The external bias voltage should be within the specified input common voltage (VCM) range. This can be achieved using external biasing resistors in the kΩ range (RB1 and RB2) or another low-noise voltage reference. This will ensure the input swing crosses the threshold voltage at a point where the input slew rate is the highest. If the LVCMOS driver cannot achieve sufficient swing with a DC-terminated 50Ω load at the CLKinX input as shown in Figure 26, then consider connecting the 50Ω load termination to ground through a capacitor (CAC). This AC termination blocks the DC load current on the driver, so the voltage swing at the input is determined by the voltage divider formed by the source (Ro+Rs) and 50Ω load resistors. The value for CAC depends on the trace delay, Td, of the 50Ω transmission line, where CAC >= 3*Td/50Ω. 22 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Driving the Clock Inputs (continued) CMOS Driver VO,PP Rs VO,PP/2 VCC 50: Trace VBB ~ (VO,PP/2) x 0.5 50: LMK Input RB1 VCC RB2 0.1 PF Figure 26. Single-Ended LVCMOS Input, DC Coupling with Common Mode Biasing If the crystal oscillator circuit is not used, it is possible to drive the OSCin input with an single-ended external clock as shown in Figure 27. The input clock should be AC coupled to the OSCin pin, which has an internallygenerated input bias voltage, and the OSCout pin should be left floating. While OSCin provides an alternative input to multiplex an external clock, it is recommended to use either universal input (CLKinX) since it offers higher operating frequency, better common mode and power supply noise rejection, and greater performance over supply voltage and temperature variations. 0.1 PF 50: Trace OSCin OSCout LMK00304 RS 0.1 PF 50: CMOS Driver Figure 27. Driving OSCin with a Single-Ended Input 10.2 Crystal Interface C1 XTAL RLIM OSCin OSCout LMK00304 The LMK00304 has an integrated crystal oscillator circuit that supports a fundamental mode, AT-cut crystal. The crystal interface is shown in Figure 28. C2 Figure 28. Crystal Interface The load capacitance (CL) is specific to the crystal, but usually on the order of 18 - 20 pF. While CL is specified for the crystal, the OSCin input capacitance (CIN = 4 pF typical) of the device and PCB stray capacitance (CSTRAY ~ 1~3 pF) can affect the discrete load capacitor values, C1 and C2. For the parallel resonant circuit, the discrete capacitor values can be calculated as follows: CL = (C1 * C2) / (C1 + C2) + CIN + CSTRAY (1) Typically, C1 = C2 for optimum symmetry, so Equation 1 can be rewritten in terms of C1 only: CL = C12 / (2 * C1) + CIN + CSTRAY (2) Finally, solve for C1: C1 = (CL - CIN - CSTRAY)*2 (3) Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 23 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Crystal Interface (continued) Electrical Characteristics provides crystal interface specifications with conditions that ensure start-up of the crystal, but it does not specify crystal power dissipation. The designer will need to ensure the crystal power dissipation does not exceed the maximum drive level specified by the crystal manufacturer. Overdriving the crystal can cause premature aging, frequency shift, and eventual failure. Drive level should be held at a sufficient level necessary to start-up and maintain steady-state operation. The power dissipated in the crystal, PXTAL, can be computed by: PXTAL = IRMS2 * RESR*(1 + C0/CL)2 where • • • • IRMS is the RMS current through the crystal. RESR is the max. equivalent series resistance specified for the crystal CL is the load capacitance specified for the crystal C0 is the min. shunt capacitance specified for the crystal (4) IRMS can be measured using a current probe (e.g. Tektronix CT-6 or equivalent) placed on the leg of the crystal connected to OSCout with the oscillation circuit active. As shown in Figure 28, an external resistor, RLIM, can be used to limit the crystal drive level, if necessary. If the power dissipated in the selected crystal is higher than the drive level specified for the crystal with RLIM shorted, then a larger resistor value is mandatory to avoid overdriving the crystal. However, if the power dissipated in the crystal is less than the drive level with RLIM shorted, then a zero value for RLIM can be used. As a starting point, a suggested value for RLIM is 1.5 kΩ. 10.3 Termination and Use of Clock Drivers When terminating clock drivers keep in mind these guidelines for optimum phase noise and jitter performance: • Transmission line theory should be followed for good impedance matching to prevent reflections. • Clock drivers should be presented with the proper loads. – LVDS outputs are current drivers and require a closed current loop. – HCSL drivers are switched current outputs and require a DC path to ground via 50 Ω termination. – LVPECL outputs are open emitter and require a DC path to ground. • Receivers should be presented with a signal biased to their specified DC bias level (common mode voltage) for proper operation. Some receivers have self-biasing inputs that automatically bias to the proper voltage level; in this case, the signal should normally be AC coupled. It is possible to drive a non-LVPECL or non-LVDS receiver with a LVDS or LVPECL driver as long as the above guidelines are followed. Check the datasheet of the receiver or input being driven to determine the best termination and coupling method to be sure the receiver is biased at the optimum DC voltage (common mode voltage). 10.3.1 Termination for DC Coupled Differential Operation For DC coupled operation of an LVDS driver, terminate with 100 Ω as close as possible to the LVDS receiver as shown in Figure 29. 100: Trace (Differential) LVDS Driver 100: CLKoutX LVDS Receiver CLKoutX* Figure 29. Differential LVDS Operation, DC Coupling, No Biasing by the Receiver 24 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Termination and Use of Clock Drivers (continued) 50: For DC coupled operation of an HCSL driver, terminate with 50 Ω to ground near the driver output as shown in Figure 30. Series resistors, Rs, may be used to limit overshoot due to the fast transient current. Because HCSL drivers require a DC path to ground, AC coupling is not allowed between the output drivers and the 50 Ω termination resistors. Rs CLKoutX HCSL Driver HCSL Receiver 50: Traces Rs 50: CLKoutX* Figure 30. HCSL Operation, DC Coupling For DC coupled operation of an LVPECL driver, terminate with 50 Ω to Vcco - 2 V as shown in Figure 31. Alternatively terminate with a Thevenin equivalent circuit as shown in Figure 32 for Vcco (output driver supply voltage) = 3.3 V and 2.5 V. In the Thevenin equivalent circuit, the resistor dividers set the output termination voltage (VTT) to Vcco – 2 V. 50: Vcco - 2V CLKoutX 100: Trace (Differential) LVPECL Driver LVPECL Receiver 50: CLKoutX* Vcco - 2V Figure 31. Differential LVPECL Operation, DC Coupling RPD RPU Vcco CLKoutX 100: Trace (Differential) LVPECL Driver LVPECL Receiver RPD VTT 120: 82: ~1.3V 2.5V 250: 62.5: 0.5V RPD RPU 3.3V RPU CLKoutX* Vcco Vcco Figure 32. Differential LVPECL Operation, DC Coupling, Thevenin Equivalent Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 25 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Termination and Use of Clock Drivers (continued) 10.3.2 Termination for AC Coupled Differential Operation AC coupling allows for shifting the DC bias level (common mode voltage) when driving different receiver standards. Since AC coupling prevents the driver from providing a DC bias voltage at the receiver, it is important to ensure the receiver is biased to its ideal DC level. When driving differential receivers with an LVDS driver, the signal may be AC coupled by adding DC blocking capacitors; however the proper DC bias point needs to be established at both the driver side and the receiver side. The recommended termination scheme depends on whether the differential receiver has integrated termination resistors or not. When driving a differential receiver without internal 100 Ω differential termination, the AC coupling capacitors should be placed between the load termination resistor and the receiver to allow a DC path for proper biasing of the LVDS driver. This is shown in Figure 33. The load termination resistor and AC coupling capacitors should be placed as close as possible to the receiver inputs to minimize stub length. The receiver can be biased internally or externally to a reference voltage within the receiver’s common mode input range through resistors in the kiloohm range. When driving a differential receiver with internal 100 Ω differential termination, a source termination resistor should be placed before the AC coupling capacitors for proper DC biasing of the driver as shown in Figure 34. However, with a 100 Ω resistor at the source and the load (i.e. double terminated), the equivalent resistance seen by the LVDS driver is 50 Ω which causes the effective signal swing at the input to be reduced by half. If a self-terminated receiver requires input swing greater than 250 mVpp (differential) as well as AC coupling to its inputs, then the LVDS driver with the double-terminated arrangement in Figure 34 may not meet the minimum input swing requirement; alternatively, the LVPECL or HCSL output driver format with AC coupling is recommended to meet the minimum input swing required by the self-terminated receiver. When using AC coupling with LVDS outputs, there may be a startup delay observed in the clock output due to capacitor charging. The examples in Figure 33 and Figure 34 use 0.1 μF capacitors, but this value may be adjusted to meet the startup requirements for the particular application. 0.1 PF CLKoutX LVDS Driver 100: Trace (Differential) 100: 0.1 PF CLKoutX K: Vbias K: CLKoutX* Receiver biasing can be internal or external through resistors in K: range LVDS Driver 0.1 PF 100: CLKoutX* 0.1 PF Source termination for proper DC bias of the driver 100: Trace (Differential) 50: Vbias 50: Receiver with internal termination and biasing through 50: resistors (b) LVDS DC termination with AC coupling at source and internal termination at load. Double termination at source and load will reduce swing by half. (a) LVDS DC termination with AC coupling at load Figure 33. Differential LVDS Operation with AC Coupling to Receivers (a) Without Internal 100 Ω Termination Figure 34. Differential LVDS Operation with AC Coupling to Receivers (b) With Internal 100 Ω Termination LVPECL drivers require a DC path to ground. When AC coupling an LVPECL signal use 160 Ω emitter resistors (or 91 Ω for Vcco = 2.5 V) close to the LVPECL driver to provide a DC path to ground as shown in Figure 38. For proper receiver operation, the signal should be biased to the DC bias level (common mode voltage) specified by the receiver. The typical DC bias voltage (common mode voltage) for LVPECL receivers is 2 V. Alternatively, a Thevenin equivalent circuit forms a valid termination as shown in Figure 35 for Vcco = 3.3 V and 2.5 V. Note: this Thevenin circuit is different from the DC coupled example in Figure 32, since the voltage divider is setting the input common mode voltage of the receiver. 26 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 RT RPU RPD VBB 3.3V 160: 82: 120: 2V 2.5V 91: 62.5: 250: 2V Vcco RPD Vcco RPU RT Termination and Use of Clock Drivers (continued) CLKoutX 0.1 PF LVPECL Driver 100: Trace (Differential) 0.1 PF LVPECL Reciever RPD RT RPU CLKoutX* Vcco Figure 35. Differential LVPECL Operation, AC Coupling, Thevenin Equivalent 10.3.3 Termination for Single-Ended Operation A balun can be used with either LVDS or LVPECL drivers to convert the balanced, differential signal into an unbalanced, single-ended signal. It is possible to use an LVPECL driver as one or two separate 800 mV p-p signals. When DC coupling one of the LMK00304 LVPECL driver of a CLKoutX/CLKoutX* pair, be sure to properly terminate the unused driver. When DC coupling on of the LMK00304 LVPECL drivers, the termination should be 50 Ω to Vcco - 2 V as shown in Figure 36. The Thevenin equivalent circuit is also a valid termination as shown in Figure 37 for Vcco = 3.3 V. 50: Vcco - 2V CLKoutX 50: Trace LVPECL Driver Vcco - 2V CLKoutX* Load 50: Figure 36. Single-Ended LVPECL Operation, DC Coupling RPU Vcco CLKoutX Vcco RPD 50: Trace CLKoutX* (unused) RPD RPU LVPECL Driver Vcco RPU RPD VTT 3.3V 120: 82: ~1.3V 2.5V 250: 62.5: 0.5V Load Figure 37. Single-Ended LVPECL Operation, DC Coupling, Thevenin Equivalent Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 27 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Termination and Use of Clock Drivers (continued) RT When AC coupling an LVPECL driver use a 160 Ω emitter resistor (or 91 Ω for Vcco = 2.5 V) to provide a DC path to ground and ensure a 50 Ω termination with the proper DC bias level for the receiver. The typical DC bias voltage for LVPECL receivers is 2 V. If the companion driver is not used, it should be terminated with either a proper AC or DC termination. This latter example of AC coupling a single-ended LVPECL signal can be used to measure single-ended LVPECL performance using a spectrum analyzer or phase noise analyzer. When using most RF test equipment no DC bias point (0 VDC) is required for safe and proper operation. The internal 50 Ω termination the test equipment correctly terminates the LVPECL driver being measured as shown in Figure 38. When using only one LVPECL driver of a CLKoutX/CLKoutX* pair, be sure to properly terminated the unused driver. 50: Trace 0.1 PF LVPECL Driver RT CLKoutX* 50: 0.1 PF Vcco RT 3.3V 160: 2.5V 91: 50: CLKoutX Load Figure 38. Single-Ended LVPECL Operation, AC Coupling 28 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 11 Power Supply Recommendations 11.1 Power Supply Sequencing When powering the Vcc and Vcco pins from separate supply rails, it is recommended for the supplies to reach their regulation point at approximately the same time while ramping up, or reach ground potential at the same time while ramping down. Using simultaneous or ratiometric power supply sequencing prevents internal current flow from Vcc to Vcco pins that could occur when Vcc is powered before Vcco. 11.2 Current Consumption and Power Dissipation Calculations The current consumption values specified in Electrical Characteristics can be used to calculate the total power dissipation and IC power dissipation for any device configuration. The total VCC core supply current (ICC_TOTAL) can be calculated using Equation 5: ICC_TOTAL = ICC_CORE + ICC_BANKS + ICC_CMOS where • • • ICC_CORE is the VCC current for core logic and input blocks and depends on selected input (CLKinX or OSCin). ICC_BANKS is the VCC current for Banks A & B and depends on the selected output type (ICC_PECL, ICC_LVDS, ICC_HCSL, or 0 mA if disabled). ICC_CMOS is the VCC current for the LVCMOS output (or 0 mA if REFout is disabled). (5) Since the output supplies (VCCOA, VCCOB, VCCOC) can be powered from 3 independent voltages, the respective output supply currents (ICCO_BANK_A, ICCO_BANK_B, and ICCO_CMOS) should be calculated separately. ICCO_BANK for either Bank A or B may be taken as 50% of the corresponding output supply current specified for two banks (ICCO_PECL, ICCO_LVDS, or ICCO_HCSL) provided the output loading matches the specified conditions. Otherwise, ICCO_BANK should be calculated per bank as follows: ICCO_BANK = IBANK_BIAS + (N * IOUT_LOAD) where • • • IBANK_BIAS is the output bank bias current (fixed value). IOUT_LOAD is the DC load current per loaded output pair. N is the number of loaded output pairs (N = 0 to 2). (6) Table 6 shows the typical IBANK_BIAS values and IOUT_LOAD expressions for LVPECL, LVDS, and HCSL. For LVPECL, it is possible to use a larger termination resistor (RT) to ground instead of terminating with 50 Ω to VTT = Vcco - 2 V; this technique is commonly used to eliminate the extra termination voltage supply (VTT) and potentially reduce device power dissipation at the expense of lower output swing. For example, when Vcco is 3.3 V, a RT value of 160 Ω to ground will eliminate the 1.3 V termination supply without sacrificing much output swing. In this case, the typical IOUT_LOAD is 25 mA, so ICCO_BANK for one LVPECL bank reduces to 63 mA (vs. 67.5 mA with 50 Ω resistors to Vcco - 2 V). Table 6. Typical Output Bank Bias and Load Currents CURRENT PARAMETER LVPECL LVDS HCSL IBANK_BIAS 13 mA 11.6 mA 2.4 mA IOUT_LOAD (VOH - VTT)/RT + (VOL - VTT)/RT 0 mA (No DC load current) VOH/RT Once the current consumption is known for each supply, the total power dissipation (PTOTAL) can be calculated: PTOTAL = (VCC*ICC_TOTAL) + (VCCOA*ICCO_BANK) + (VCCOB*ICCO_BANK) + (VCCOC*ICCO_CMOS) (7) If the device is configured with LVPECL and/or HCSL outputs, then it is also necessary to calculate the power dissipated in any termination resistors (PRT_ PECL and PRT_HCSL) and in any LVPECL termination voltages (PVTT_PECL). The external power dissipation values can be calculated as follows: PRT_PECL (per LVPECL pair) = (VOH - VTT)2/RT + (VOL - VTT)2/RT PVTT_PECL (per LVPECL pair) = VTT * [(VOH - VTT)/RT + (VOL - VTT)/RT] PRT_HCSL (per HCSL pair) = VOH2 / RT (8) (9) (10) Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 29 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Finally, the IC power dissipation (PDEVICE) can be computed by subtracting the external power dissipation values from PTOTAL as follows: PDEVICE = PTOTAL - N1*(PRT_PECL + PVTT_PECL) - N2*PRT_HCSL where • • N1 is the number of LVPECL output pairs with termination resistors to VTT (usually Vcco - 2 V or GND). N2 is the number of HCSL output pairs with termination resistors to GND. (11) 11.2.1 Power Dissipation Example: Worst-Case Dissipation This example shows how to calculate IC power dissipation for a configuration to estimate worst-case power dissipation. In this case, the maximum supply voltage and supply current values specified in Electrical Characteristics are used. • Max VCC = VCCO = 3.465 V. Max ICC and ICCO values. • CLKin0/CLKin0* input is selected. • Banks A and B are configured for LVPECL: all outputs terminated with 50 Ω to VT = Vcco - 2 V. • REFout is enabled with 5 pF load. • TA = 85 °C Using the power calculations from the previous section and maximum supply current specifications, we can compute PTOTAL and PDEVICE. • From Equation 5: ICC_TOTAL = 10.5 mA + 48 mA + 5.5 mA = 64 mA • From ICCO_PECL max spec: ICCO_BANK = 50% of ICCO_PECL = 81.5 mA • From Equation 7: PTOTAL = (3.465 V * 64 mA) + (3.465 V * 81.5 mA)+ (3.465 V * 81.5 mA) + (3.465 V * 10 mA) = 821 mW • From Equation 8: PRT_PECL = ((2.57 V - 1.47 V)2/50 Ω) + ((1.72 V - 1.47 V)2/50 Ω) = 25.5 mW (per output pair) • From Equation 9: PVTT_PECL = 1.47 V * [ ((2.57 V - 1.47 V) / 50 Ω) + ((1.72 V - 1.47 V) / 50 Ω) ] = 39.5 mW (per output pair) • From Equation 10: PRT_HCSL = 0 mW (no HCSL outputs) • From Equation 11: PDEVICE = 821 mW - (4 * (25.5 mW + 39.5 mW)) - 0 mW = 561 mW In this worst-case example, the IC device will dissipate about 561 mW or 68% of the total power (821 mW), while the remaining 32% will be dissipated in the emitter resistors (102 mW for 4 pairs) and termination voltage (158 mW into Vcco - 2 V). Based on θJA of 38.1 °C/W, the estimate die junction temperature would be about 21.4 °C above ambient, or 106.4 °C when TA = 85 °C. 11.3 Power Supply Bypassing The Vcc and Vcco power supplies should have a high-frequency bypass capacitor, such as 0.1 uF or 0.01 uF, placed very close to each supply pin. 1 uF to 10 uF decoupling capacitors should also be placed nearby the device between the supply and ground planes. All bypass and decoupling capacitors should have short connections to the supply and ground plane through a short trace or via to minimize series inductance. 11.3.1 Power Supply Ripple Rejection In practical system applications, power supply noise (ripple) can be generated from switching power supplies, digital ASICs or FPGAs, etc. While power supply bypassing will help filter out some of this noise, it is important to understand the effect of power supply ripple on the device performance. When a single-tone sinusoidal signal is applied to the power supply of a clock distribution device, such as LMK00304, it can produce narrow-band phase modulation as well as amplitude modulation on the clock output (carrier). In the single-side band phase noise spectrum, the ripple-induced phase modulation appears as a phase spur level relative to the carrier (measured in dBc). 30 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 Power Supply Bypassing (continued) For the LMK00304, power supply ripple rejection, or PSRR, was measured as the single-sideband phase spur level (in dBc) modulated onto the clock output when a ripple signal was injected onto the Vcco supply. The PSRR test setup is shown in Figure 39. Ripple Source Vcco Clock Source Power Supplies Bias-Tee Vcc OUT+ IN+ Limiting Amp IC IN- OUTDUT Board OUT Phase Noise Analyzer Scope Measure 100 mVPP ripple on Vcco at IC Measure single sideband phase spur power in dBc Figure 39. PSRR Test Setup A signal generator was used to inject a sinusoidal signal onto the Vcco supply of the DUT board, and the peakto-peak ripple amplitude was measured at the Vcco pins of the device. A limiting amplifier was used to remove amplitude modulation on the differential output clock and convert it to a single-ended signal for the phase noise analyzer. The phase spur level measurements were taken for clock frequencies of 156.25 MHz and 312.5 MHz under the following power supply ripple conditions: • Ripple amplitude: 100 mVpp on Vcco = 2.5 V • Ripple frequencies: 100 kHz, 1 MHz, and 10 MHz Assuming no amplitude modulation effects and small index modulation, the peak-to-peak deterministic jitter (DJ) can be calculated using the measured single-sideband phase spur level (PSRR) as follows: DJ (ps pk-pk) = [(2*10(PSRR / 20)) / (π*fCLK)] * 1012 (12) The “PSRR vs. Ripple Frequency” plots in Typical Characteristics show the ripple-induced phase spur levels for the differential output types at 156.25 MHz and 312.5 MHz . The LMK00304 exhibits very good and well-behaved PSRR characteristics across the ripple frequency range for all differential output types. The phase spur levels for LVPECL are below -64 dBc at 156.25 MHz and below -62 dBc at 312.5 MHz. Using Equation 12, these phase spur levels translate to Deterministic Jitter values of 2.57 ps pk-pk at 156.25 MHz and 1.62 ps pk-pk at 312.5 MHz. Testing has shown that the PSRR performance of the device improves for Vcco = 3.3 V under the same ripple amplitude and frequency conditions. 11.4 Thermal Management Power dissipation in the LMK00304 device can be high enough to require attention to thermal management. For reliability and performance reasons the die temperature should be limited to a maximum of 125 °C. That is, as an estimate, TA (ambient temperature) plus device power dissipation times θJA should not exceed 125 °C. The package of the device has an exposed pad that provides the primary heat removal path as well as excellent electrical grounding to the printed circuit board. To maximize the removal of heat from the package a thermal land pattern including multiple vias to a ground plane must be incorporated on the PCB within the footprint of the package. The exposed pad must be soldered down to ensure adequate heat conduction out of the package. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 31 LMK00304 SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 www.ti.com Thermal Management (continued) A recommended land and via pattern is shown in Figure 40. More information on soldering WQFN packages can be obtained at: http://www.ti.com/packaging. 3.1 mm, min 0.2 mm, typ 1.27 mm, typ Figure 40. Recommended Land and Via Pattern To minimize junction temperature it is recommended that a simple heat sink be built into the PCB (if the ground plane layer is not exposed). This is done by including a copper area of about 2 square inches on the opposite side of the PCB from the device. This copper area may be plated or solder coated to prevent corrosion but should not have conformal coating (if possible), which could provide thermal insulation. The vias shown in Figure 40 should connect these top and bottom copper layers and to the ground layer. These vias act as “heat pipes” to carry the thermal energy away from the device side of the board to where it can be more effectively dissipated. 32 Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 LMK00304 www.ti.com SNAS577F – FEBRUARY 2012 – REVISED MARCH 2016 12 Device and Documentation Support 12.1 Documentation Support 12.1.1 Related Documentation Common Data Transmission Parameters and their Definitions, Application Note AN-912 (SNLA036) 12.2 Community Resources The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 12.3 Trademarks E2E is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. 12.4 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 12.5 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Submit Documentation Feedback Copyright © 2012–2016, Texas Instruments Incorporated Product Folder Links: LMK00304 33 PACKAGE OPTION ADDENDUM www.ti.com 6-Mar-2015 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LMK00304SQ/NOPB ACTIVE WQFN RTV 32 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 85 K00304 LMK00304SQE/NOPB ACTIVE WQFN RTV 32 250 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 85 K00304 LMK00304SQX/NOPB ACTIVE WQFN RTV 32 2500 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 85 K00304 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 13-Jul-2016 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LMK00304SQ/NOPB WQFN RTV 32 LMK00304SQE/NOPB WQFN RTV LMK00304SQX/NOPB WQFN RTV SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1000 178.0 12.4 5.3 5.3 1.3 8.0 12.0 Q1 32 250 178.0 12.4 5.3 5.3 1.3 8.0 12.0 Q1 32 2500 330.0 12.4 5.3 5.3 1.3 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 13-Jul-2016 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMK00304SQ/NOPB WQFN RTV 32 1000 213.0 191.0 55.0 LMK00304SQE/NOPB WQFN RTV 32 250 213.0 191.0 55.0 LMK00304SQX/NOPB WQFN RTV 32 2500 367.0 367.0 35.0 Pack Materials-Page 2 MECHANICAL DATA RTV0032A SQA32A (Rev B) www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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