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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. LMX2594 snas696 ? march 2017 LMX2594 15 ghz wideband pllatinum ? rf synthesizer with phase synchronization and jesd204b support 1 1 features 1 ? 10-mhz to 15-ghz output frequency ? ? 110 dbc/hz phase noise at 100 khz offset with 15 ghz carrier ? 45-fs rms jitter at 7.5 ghz (100 hz to 100 mhz) ? programmable output power up to 7 dbm at 15 ghz ? pll key specifications ? figure of merit: ? 236 dbc/hz ? normalized 1/f noise: ? 129 dbc/hz ? high phase detector frequency ? 400-mhz integer mode ? 300-mhz fractional mode ? 32-bit fractional-n divider ? remove integer boundary spurs with programmable input multiplier ? synchronize output phase across multiple devices ? support for sysref with 9-ps resolution programmable delay ? frequency ramp and chirp generation ability for fmcw applications ? < 20- s vco calibration speed ? 3.3-v single power supply operation 2 applications ? 5g and mm-wave wireless infrastructure ? test and measurement equipment ? radar ? mimo ? phased array antennas and beam forming ? high speed data converter clocking (supports jesd204b) 3 description the LMX2594 is a high-performance, wideband pll with integrated vcos that can generate any frequency from 10 mhz to 15 ghz without using an internal doubler, thus eliminating the need for sub- harmonic filters. the high performance pll with figure of merit of ? 236 dbc/hz and high phase detector frequency can attain very low in-band noise and integrated jitter. the high speed n-divider has no pre-divider, thus significantly reducing the amplitude and number of spurs. there is also a programmable input multiplier to mitigate integer boundary spurs. the LMX2594 allows users to synchronize the output of multiple devices and also enables applications that need deterministic delay between input and output. a frequency ramp generator can synthesize up to 2 segments of ramp in an automatic ramp generation option or a manual option for maximum flexibility. the fast calibration algorithm allows changing frequencies faster than 20 s. the LMX2594 adds support for generating or repeating sysref (compliant to jesd204b standard) making it an ideal low-noise clock source for high-speed data converters. fine delay adjustment (9 ps resolution) is provided in this configuration to account for delay differences of board traces. the output drivers within LMX2594 delivers output power as high as 7 dbm at 15 ghz carrier frequency. the device runs from a single 3.3 v supply and has integrated ldos that eliminate the need for on-board low noise ldos. device information (1) part number package body size (nom) LMX2594 vqfn (40) 6.00 mm 6.00 mm (1) for all available packages, see the orderable addendum at the end of the data sheet. simplified schematic charge pump vtune cpout rfoutap sigma-delta modulator n divider oscin douber post-r divider multiplier pre-r divider i vcc rfoutam rfoutbp vcc channel divider loop filter phase detector serial interface control sdi sck csb muxout oscinp oscinm input signal rfoutbm mux mux sysref productfolder ordernow technical documents tools & software support &community
2 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table of contents 1 features .................................................................. 1 2 applications ........................................................... 1 3 description ............................................................. 1 4 revision history ..................................................... 2 5 pin configuration and functions ......................... 3 6 specifications ......................................................... 5 6.1 absolute maximum ratings ...................................... 5 6.2 esd ratings .............................................................. 5 6.3 recommended operating conditions ....................... 5 6.4 thermal information .................................................. 5 6.5 electrical characteristics ........................................... 6 6.6 timing requirements ................................................ 8 6.7 typical characteristics ............................................ 10 7 detailed description ............................................ 21 7.1 overview ................................................................. 21 7.2 functional block diagram ....................................... 22 7.3 feature description ................................................. 22 7.4 device functional modes ........................................ 40 7.5 programming ........................................................... 41 7.6 register maps and descriptions ............................ 41 8 application and implementation ........................ 58 8.1 application information ............................................ 58 8.2 typical application ................................................. 60 9 power supply recommendations ...................... 63 10 layout ................................................................... 64 10.1 layout guidelines ................................................. 64 10.2 layout example .................................................... 65 11 device and documentation support ................. 66 11.1 device support ...................................................... 66 11.2 documentation support ........................................ 66 11.3 receiving notification of documentation updates 66 11.4 community resources .......................................... 66 11.5 trademarks ........................................................... 66 11.6 electrostatic discharge caution ............................ 66 11.7 glossary ................................................................ 66 12 mechanical, packaging, and orderable information ........................................................... 67 4 revision history date revision notes march 2017 * initial release
3 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 5 pin configuration and functions rha package 40-pin vqfn top view ce gnd vbiasvco gnd sync gnd vccdig oscinp oscinm vregin vcccp cpout gnd gnd vccmash sck sdi rfoutbm rfoutbp muxout rampclk vrefvco2 sysrefreq vbiasvco2 vccvco2 gnd csb rfoutap rfoutam vccbuf gnd gnd vregvco vccvco vrefvco vtune gnd vbiasvarac rampdir gnd gnd
4 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated pin functions pin i/o description no. name 1 ce input chip enable input. active high powers on the device. 2, 4, 25, 31, 34, 39, 40 gnd ground vco ground 3 vbiasvco bypass vco bias. requires connecting 10 f capacitor to vco ground. place close to pin. 5 sync input phase synchronization pin. has programmable threshold. 6, 14 gnd ground digital ground 7 vccdig supply digital supply. ti recommends bypassing with a 0.1 f capacitor to digital ground. 8 oscinp input reference input clock (+). high-impedance self-biasing pin. requires ac coupling capacitor. (0.1 f recommended) 9 oscinm input reference input clock ( ? ). high impedance self-biasing pin. requires ac coupling capacitor. (0.1 f recommended) 10 vregin bypass input reference path regulator output. requires connecting 1 f capacitor to ground. place close to pin. 11 vcccp supply charge pump supply.ti recommends bypassing with a 0.1 f capacitor to charge pump ground. 12 cpout output charge pump output. ti recommends connecting c1 of loop filter close to pin. 13 gnd ground charge pump ground 15 vccmash supply digital supply. ti recommends bypassing with a 0.1 f and 10 f capacitor to digital ground. 16 sck input spi clock. high impedance cmos input. 1.8 to 3.3 v logic. 17 sdi input spi data. high impedance cmos input. 1.8 to 3.3 v logic. 18 rfoutbm output differential output b ( ? ). requires pullup (typically 50- resistor) to v cc as close as possible to pin. can be used as an output signal or sysref output. 19 rfoutbp output differential output b (+). requires pullup (typically 50- resistor) to v cc as close as possible to pin. can be used as an output signal or sysref output. 20 muxout output multiplexed output pin ? lock detect, readback, diagnostics, ramp status 21 vccbuf supply output buffer supply. ti recommends bypassing with a 0.1 f capacitor to rfout ground. 22 rfoutam output differential output a ( ? ). requires connecting 50- resistor pullup to vcc as close as possible to pin. 23 rfoutap output differential output a (+). requires connecting 50- resistor pullup to vcc as close as possible to pin. 24 csb input spi latch. chip select bar . high-impedance cmos input. 1.8 to 3.3 v logic. 26 vccvco2 supply vco supply. ti recommends bypassing with a 0.1 f and 10 f capacitor to vco ground. 27 vbiasvco2 bypass vco bias. requires connecting 1 f capacitor to vco ground. 28 sysrefreq input sysref request input for jesd204b support 29 vrefvco2 bypass vco supply reference. requires connecting 10 f capacitor to vco ground. 30 rampclk input input pin for ramping mode that can be used to clock the ramp in manual ramping mode or as a trigger input. 32 rampdir input input pin for ramping mode that can be used to change ramp direction in manual ramping mode or as a trigger input. 33 vbiasvarac bypass vco varactor bias. requires connecting 10 f capacitor to vco ground. 35 vtune input vco tuning voltage input. 36 vrefvco bypass vco supply reference. requires connecting 10 f capacitor to ground. 37 vccvco supply vco supply. recommend bypassing with 0.1 f and 10 f capacitor to ground. 38 vregvco bypass vco regulator node. requires connecting 1 f capacitor to ground. dap gnd ground rfout ground
5 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated (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. 6 specifications 6.1 absolute maximum ratings over operating free-air temperature range (unless otherwise noted) (1) min max unit v cc power supply voltage ? 0.3 3.6 v t j junction temperature ? 40 150 c t stg storage temperature ? 65 150 c (1) 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 xxx v may actually have higher performance. (2) 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 yyy v may actually have higher performance. 6.2 esd ratings value unit v (esd) electrostatic discharge human-body model (hbm), per ansi/esda/jedec js-001 (1) 2000 v charged-device model (cdm), per jedec specification jesd22- c101 (2) 750 6.3 recommended operating conditions over operating free-air temperature range (unless otherwise noted) min nom max unit v cc power supply voltage 3.15 3.3 3.45 v t a ambient temperature ? 40 25 85 c t j junction temperature 125 c (1) for more information about traditional and new thermal metrics, see the semiconductor and ic package thermal metrics application report. (2) dap 6.4 thermal information thermal metric (1) LMX2594 unit rha (vqfn) 40 pins r ja junction-to-ambient thermal resistance 30.5 c/w r jc(top) junction-to-case (top) thermal resistance (2) 15.3 c/w r jb junction-to-board thermal resistance 5.4 c/w jt junction-to-top characterization parameter 0.2 c/w jb junction-to-board characterization parameter 5.3 c/w r jc(bot) junction-to-case (bottom) thermal resistance 0.9 c/w
6 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated (1) output power, spurs, and harmonics can vary based on board layout and components. (2) for lower vco frequencies, the n divider minimum value can limit the phase-detector frequency. (3) the pll noise contribution is measured using a clean reference and a wide loop bandwidth and is composed into flicker and flat components. pll_flat = pll_fom + 20 log(fvco/fpd) + 10 log(fpd / 1hz). pll_flicker (offset) = pll_flicker_norm + 20*log(fvco / 1ghz) ? 10*log(offset / 10khz). once these two components are found, the total pll noise can be calculated as pll_noise = 10 log(10 pll_flat / 10 + 10 pll_flicker / 10 ) 6.5 electrical characteristics 3.15 v v cc 3.45 v, ? 40 c t a +85 c. typical values are at v cc = 3.3 v, 25 c (unless otherwise noted). parameter test conditions min typ max unit power supply v cc supply voltage 3.15 3.3 3.45 v i cc supply current outa_pd = 0, outb_pd = 1 outa_mux = outb_mux = 1 outa_pwr = 31, cpg=7 f osc = f pd = 100 mhz, f vco = f out = 14 ghz p out = 3 dbm with 50- resistor pullup 340 ma power on reset current reset=1 170 power down current powerdown=1 5 output characteristics p out single-ended output power (1) 50- resistor pullup outx_pwr = 50 f out = 8 ghz 5 dbm f out = 15 ghz 2 1-nh inductor pullup outx_pwr = 50 f out = 8 ghz 10 f out = 15 ghz 7 xtalk isolation between outputs a and b. measured on output a outa_mux = vco outb_mux = channel divider ? 50 dbc h2 second harmonic (1) outa_mux = vco f vco = 8 ghz -20 dbc h3 third harmonic (1) outa_mux = vco f vco = 8 ghz -50 dbc input signal path f oscin reference input frequency osc_2x = 0 5 1400 mhz osc_2x = 1 5 200 v oscin reference input voltage ac-coupled required (2) 0.2 2 vpp f mult multiplier frequency (only applies when multiplier is enabled) input range 30 70 mhz output range 180 250 phase detector and charge pump f pd phase detector frequency (2) integer mode frac_order = 0 0.125 400 mhz fractional mode frac_order = 1,2,3 5 300 frac_order = 4 5 240 i cpout charge-pump leakage current cpg = 0 15 na effective charge pump current. this is the sum of the up and down currents cpg = 4 3 ma cpg = 1 6 cpg = 5 9 cpg = 3 12 cpg = 7 15 pn pll_1/f normalized pll 1/f noise f pd = 100 mhz, f vco = 12 ghz (3) ? 129 dbc/hz pn pll_flat normalized pll noise floor ? 236 dbc/hz
7 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated electrical characteristics (continued) 3.15 v v cc 3.45 v, ? 40 c t a +85 c. typical values are at v cc = 3.3 v, 25 c (unless otherwise noted). parameter test conditions min typ max unit (4) see application and implementation for more details on the different vco calibration modes. vco characteristics pn vco vco phase noise vco1 f vco = 8.0 ghz 10 khz ? 80 dbc/hz 100 khz ? 107 1 mhz ? 128 10 mhz ? 148 90 mhz ? 157 vco2 f vco = 9.2 ghz 10 khz ? 79 100 khz ? 105 1 mhz ? 127 10 mhz ? 147 90 mhz ? 157 vco3 f vco = 10.3 ghz 10 khz ? 77 100 khz ? 104 1 mhz ? 126 10 mhz ? 147 90 mhz ? 157 vco4 f vco = 11.3 ghz 10 khz ? 76 100 khz ? 103 1 mhz ? 125 10 mhz ? 145 90 mhz ? 158 vco5 f vco = 12.5 ghz 10 khz ? 74 100 khz ? 100 1 mhz ? 123 10 mhz ? 144 90 mhz ? 157 vco6 f vco = 13.3 ghz 10 khz ? 73 100 khz ? 100 1 mhz ? 122 10 mhz ? 143 90 mhz ? 155 vco7 f vco = 14.5 ghz 10 khz ? 73 100 khz ? 99 1 mhz ? 121 10 mhz ? 143 90 mhz ? 152 t vcocal vco calibration speed, switch across the entire frequency band, f osc = 200 mhz, f pd = 100 mhz (4) no assist 50 s partial assist 35 close frequency 20 full assist 5
8 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated electrical characteristics (continued) 3.15 v v cc 3.45 v, ? 40 c t a +85 c. typical values are at v cc = 3.3 v, 25 c (unless otherwise noted). parameter test conditions min typ max unit k vco vco gain 8.0 ghz 73 mhz/v 9.2 ghz 76 10.3 ghz 94 11.3 ghz 86 12.5 ghz 149 13.3 ghz 135 14.5 ghz 154 | t cl | allowable temperature drift when vco is not re-calibrated ramp_en = 0 or ramp_manual= 1 125 c h2 vco second harmonic f vco = 8 ghz, divider disabled ? 20 dbc h3 vco third haromonic f vco = 8 ghz, divider disabled ? 50 sync pin and phase alignment f oscin sy nc maximum usable oscin with sync pin figure 22 category 3 0 100 mhz categories1 and 2 0 1400 digital interface, applies to sclk, sda, csb, rampdir, rampclk, muxout, sync (cmos mode), sysrefreq (cmos mode) v ih high level input voltage 1.4 vcc v v il low level input voltage 0 0.4 v i ih high level input current ? 25 25 a i il low level input current ? 25 25 a v oh high level output voltage muxout pin load current = ? 10 ma v cc ? 0.4 v v ol high level output current load current = 10 ma 0.4 v 6.6 timing requirements (3.15 v v cc 3.45 v, ? 40 c t a +85 c, except as specified. nominal values are at v cc = 3.3 v, t a = 25 c) min nom max unit sync, sysrefreq, rampclk, and rampdir pins t setup setup time for pin relative to oscin rising edge sync pin 2.5 ns sysrefreq pin 2.5 t hold hold time for sync pin relative to oscin rising edge sync pin 2 ns sysrefreq pin 2 digital interface write specifications f spi write spi write speed t cwl + t cwh > 13.333 ns 75 mhz t es clock to enable low time see figure 1 5 ns t cs data to clock setup time 2 ns t ch data to clock hold time 2 ns t cwh clock pulse width high 5 ns t cwl clock pulse width low 5 ns t ces enable to clock setup time 5 ns t ewh enable pulse width high 2 ns
9 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated timing requirements (continued) (3.15 v v cc 3.45 v, ? 40 c t a +85 c, except as specified. nominal values are at v cc = 3.3 v, t a = 25 c) min nom max unit digital interface readback specifications f spi readb ack spi readback speed see figure 2 50 mhz t es clock to enable low time 10 ns t cs clock to data wait time 10 ns t cwh clock pulse width high 10 ns t cwl clock pulse width low 10 ns t ces enable to clock setup time 10 ns t ewh enable pulse width high 10 ns figure 1. serial data input timing diagram there are several other considerations for writing on the spi: ? the r/w bit must be set to 0. ? the data on sda pin is clocked into a shift register on each rising edge on the sck pin. ? the csb must be held low for data to be clocked. device will ignore clock pulses if csb is held high. ? the csb transition from high to low must occur when sck is low. ? when sck and sda lines are shared between devices, ti recommends hold the csb line high on the device that is not to be clocked. figure 2. serial data readback timing diagram there are several other considerations for spi readback: ? the r/w bit must be set to 1. ? the muxout pin will always be low for the address portion of the transaction. ? the data on sda is clocked out on the rising edge of sck. ? the data portion of the transition on the sda line is always ignored. t ces t cs r/w a6 a5 t cwh t cwl a0 msb sda csb t ce t ewh sck rb15 rb14 rb0 lsb muxout t ces t cs r/w sdk a5 t ch t cwh t cwl a0 d15 d14 d0 msb lsb t ce t ewh sda csb
10 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 6.7 typical characteristics figure 3. closed loop phase noise with f osc = 100 mhz and f pd = 200 mhz figure 4. calculation of pll noise metrics of pll f pd =100 mhz, f vco = 12 ghz -120 -115 -110 -105 -100 -95 -90 -85 -80 1.e+02 1.e+03 1.e+04 1.e+05 flicker (pll 1/f =-129.2 dbc/hz) flat (fom = -236.2 dbc/hz) modeled phase noise measurement
11 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 5. output power vs pullup 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 3000 5000 7000 9000 11000 13000 15000 output power (dbm) frequeny (mhz) resistor pull-up (outx_pwr=50) inductor pull-up (outx_pwr=50)
12 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 6. closed loop phase noise at 15 ghz with f osc = 100 mhz and f pd = 200 mhz
13 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 7. closed loop phase noise at 13 ghz with f osc = 100 mhz and f pd = 200 mhz
14 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 8. closed loop phase noise at 11 ghz with f osc = 100 mhz and f pd = 200 mhz
15 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 9. closed loop phase noise at 9 ghz with f osc = 100 mhz and f pd = 200 mhz
16 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 10. closed loop phase noise at 7.5 ghz with f osc = 100 mhz and f pd = 200 mhz
17 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 11. closed loop phase noise at 3.5 ghz with f vco = 100, f osc = 100 mhz, and f pd = 200 mhz
18 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 12. additive vco divider noise floor (adds to the divided far out vco noise when output divider is used.) -180 -175 -170 -165 -160 -155 -150 -145 10 100 1000 additive divider noise (dbc/hz) fout (mhz)
19 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) figure 13. vco ramping 12 - 12.125 ghz without need to calibrate figure 14. vco ramping 7.5 to 15 ghz triangle wave with vco calibration (the glitches in the plot are due to inability of the measurement equipment to track the vco while calibrating.) 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 0 2 4 6 8 10 frequency (mhz) time (ms)
20 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical characteristics (continued) a. figure 15. vco unassisted calibration from 7.5 - 14 ghz in 33.6 s chdiv=2, f osc =200 mhz, f pd =100 mhz a. figure 16. vco calibration with partial assist from 7.5 - 14 ghz in 25.2 s chdiv=2, f osc = 200 mhz, f pd = 100 mhz.
21 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7 detailed description 7.1 overview the LMX2594 is a high-performance, wideband frequency synthesizer with integrated vco and output divider. the vco operates from 7.5 to 15 ghz and this can be combined with the output divider to produce any frequency in the range of 10 mhz to 15 ghz. within the input path there are two dividers and a multiplier for flexible frequency planning. the multiplier also allows reduction of spurs by moving the frequencies away from the integer boundary. the pll is fractional-n pll with programmable delta-sigma modulator up to 4 th order. the fractional denominator is a programmable 32-bit long, which can provide fine frequency steps easily below 1-hz resolution as well as be used to do exact fractions like 1/3, 7/1000, and many others. the phase frequency detector goes up to 300 mhz in fractional mode or 400 mhz in integer mode, although minimum n divider values must also be taken into account. for applications where deterministic or adjustable phase is desired, the sync pin can be used to get the phase relationship between the oscin and rfout pins deterministic. once this is done, the phase can be adjusted in very fine steps of the vco period divided by the fractional denominator. the ultra-fast vco calibration is ideal for applications where the frequency must be swept or abruptly changed. the frequency can be manually programmed, or the device can be set up to do ramps and chirps. the jesd204b support includes using the rfoutb output to create a differential sysref output that can be either a single pulse or a series of pulses that occur at a programmable distance away from the rising edges of the output signal. the LMX2594 device requires only a single 3.3 v power supply. the internal power supplies are provided by integrated ldos, eliminating the need for high performance external ldos. the digital logic for the spi interface and is compatible with voltage levels from 1.8 to 3.3 v. table 1 shows the range of several of the dividers, multipliers, and fractional settings. table 1. range of dividers, multipliers, and fractional settings parameter min max comments outputs enabled 0 2 oscin doubler 0 (1x) 1 (2x) the low noise doubler can be used to increase the phase detector frequency to improve phase noise and avoid spurs. this is in reference to the osc_2x bit. pre-r divider 1 (bypass) 128 only use the pre r divider if the multiplier is used and the input frequency is too high for the multiplier. multiplier 3 7 this is in reference to the mult word. post-r divider 1 (bypass) 255 the maximum input frequency for the post-r divider is 250 mhz. use the pre r divider if necessary. n divider 28 524287 the minimum divide depends on modulator order and vco frequency. see n divider and fractional circuitry for more details. fractional numerator/ denominator 1 (integer mode) 2 32 ? 1 = 4294967295 the fractional denominator is programmable and can assume any value between 1 and 2 32 ? 1; it is not a fixed denominator. fractional order 0 4 order 0 is integer mode and the order can be programmed channel divider 1 (bypass) 768 this is the series of several dividers. also, be aware that above 10 ghz, the maximum allowable channel divider value is 6. output frequency 10 mhz 15 ghz this is implied by the minimum vco frequency divided by the maximum channel divider value.
22 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.2 functional block diagram 7.3 feature description 7.3.1 reference oscillator input the oscin pins are used as a frequency reference input to the device. the input is high impedance and requires ac-coupling caps at the pin. the oscin pins can be driven single-ended with a cmos clock or xo. differential clock input is also supported, making it easier to interface with high-performance system clock devices such as ti ? s lmk series clock devices. as the oscin signal is used as a clock for the vco calibration, a proper reference signal must be applied at the oscin pin at the time of programming fcal_en. 7.3.2 reference path the reference path consists of an oscin doubler (osc_2x), pre-r divider, multiplier (mult) and a post-r divider. figure 17. reference path diagram the oscin doubler (osc_2x) can double up low oscin frequencies. pre-r (pll_r_pre) and post-r (pll_r) dividers both divide frequency down while the multiplier (mult) multiplies frequency up. the purposes of adding a multiplier is to reduce integer boundary spurs or to increase the phase detector frequency. note that the multiplier cannot be used if the oscin doubler is used. the phase detector frequency, f pd , is calculated as follows: f pd = f osc osc_2x mult / (pll_r_pre pll_r) (1) oscin douber post-r divider multiplier pre-r divider phase frequency detector oscin charge pump vtune cpout rfoutap sigma-delta modulator n divider oscin douber post-r divider multiplier pre-r divider i vcc rfoutam rfoutbp vcc channel divider loop filter phase detector serial interface control sdi sck csb muxout oscinp oscinm input signal rfoutbm mux mux sysref
23 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated feature description (continued) 7.3.2.1 oscin doubler (osc_2x) the oscin doubler allows one to double the input reference frequency up to 400 mhz. this doubler adds minimal noise and is useful for raising the phase detector frequency for better phase noise and also to avoid spurs. when the phase-detector frequency is increased, the flat portion of the pll phase noise improves. figure 18. benefit of using the osc_2x doubler at 14 ghz 7.3.2.2 pre-r divider (pll_r_pre) the pre-r divider is useful for reducing the input frequency so that the programmable multiplier (mult) can be used or to help meet the maximum 250 mhz input frequency limitation to the pll-r divider. otherwise, it does not have to be used. 7.3.2.3 programmable multiplier (mult) the mult is useful for shifting the phase-detector frequency to avoid integer boundary spurs. the multiplier allows a multiplication of 3, 4, 5, 6, or 7. be aware that unlike the doubler, the programmable multiplier degrades the pll figure of merit; however, this only would matter for a clean reference and if the loop bandwidth was wide. 7.3.2.4 post-r divider (pll_r) the post-r divider can be used to further divide down the frequency to the phase detector frequency. when it is used (pll_r > 1), the input frequency to this divider is limited to 250 mhz. -120 -115 -110 -105 -100 -95 -90 1.e+03 1.e+04 1.e+05 1.e+06 phase noise (dbc/hz) offset (hz) doubler disabled, fpd=100 mhz doubler enabled, fpd=200 mhz
24 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated feature description (continued) 7.3.3 pll phase detector and charge pump the phase detector compares the outputs of the post-r divider and n divider and generates a correction current corresponding to the phase error until the two signals are aligned in phase. this charge-pump current is software programmable to many different levels, allowing modification of the closed loop bandwidth of the pll. see application section on phase noise due to the charge pump. 7.3.4 n divider and fractional circuitry the n divider includes fractional compensation and can achieve any fractional denominator from 1 to (2 32 ? 1). the integer portion of n is the whole part of the n divider value, and the fractional portion, n frac = num / den, is the remaining fraction. in general, the total n divider value is determined by n + num / den. the n, num and den are software programmable. the higher the denominator, the finer the resolution step of the output. for example, even when using f pd = 200 mhz, the output can increment in steps of 200 mhz / 2 32 = 0.047 hz. equation 2 shows the relationship between the phase detector and vco frequencies. note that in sync mode, there is an extra divider that is not shown in equation 2 . (2) the sigma-delta modulator that controls this fractional division is also programmable from integer mode to fourth order. to make the fractional spurs consistent, the modulator is reset any time that the r0 register is programmed. the n divider has minimum value restrictions based on the modulator order and vco frequency. furthermore, the pfd_dly_sel bit must be programmed in accordance to the table 2 . table 2. minimum n divider restrictions frac_order f vco (mhz) minimum n pfd_dly_sel 0 12500 28 1 > 12500 32 2 1 10000 28 1 10000-12500 32 2 > 12250 36 3 2 10000 32 2 > 10000 36 3 3 10000 36 3 > 10000 40 4 4 10000 44 5 > 10000 48 6 7.3.5 muxout pin the muxout pin can be used to readback programmable states of the device or for lock detect. table 3. muxout pin configurations muxout_sel function 0 readback 1 lock detect vco pd num f f n den u ? ? 1
25 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.5.1 lock detect the muxout pin can be configured for lock detect done in by reading back the rb_ld_vtune field or using the pin as shown in the table 4 . table 4. configuring the muxout pin for lock detect field programming description ld_type 0 = vco calibration status 1 = vtune this determines if the lock detect is based on the vco tuning voltage or at the vco calibration. ld_dly 0 to 65535 only valid for vtune lock detect. this is a delay in state machine cycles. the state machine clock frequency is equal to f osc /cal_clk_div out_mute 0 = disabled 1 = enabled turns off outputs when lock detect is low. vco calibration status lock detect works by indicating a low signal whenever the vco is calibrating or the ld_dly counter is running. vtune lock detect works by checking the vtune voltage. whenever the vtune voltage is within an acceptable range and the vco is not calibrating, then vtune lock detect is high. 7.3.5.2 readback the muxout pin can be configured for to read back useful information from the device. common uses for readback are: 1. read back registers to ensure that they have been programmed to the correct value. 2. read back the lock detect status to determine if the pll is in lock. 3. read back vco calibration information so that it can be used to improve the lock time. 4. read back information to help troubleshoot. vco calibration status lock detect works by indicating a low signal whenever the vco is calibrating or the ld_dly counter is running. the delay from the ld_dly added to the true vco calibration time (t vcocal ) so it can be used to account for the analog lock time of the pll. vtune lock detect works by checking the vtune voltage. whenever the vtune voltage is within an acceptable range and the vco is not calibrating, then vtune lock detect is high. 7.3.6 vco (voltage controlled oscillator) the LMX2594 includes a fully integrated vco. the vco takes the voltage from the loop filter and converts this into a frequency. the vco frequency is related to the other frequencies and as follows: f vco = f pd n divider (3) 7.3.6.1 vco calibration to reduce the vco tuning gain and therefore improve the vco phase-noise performance, the vco frequency range is divided into several different frequency bands. the entire range, 7.5 to 15 ghz, covers an octave that allows the divider to take care of frequencies below the lower bound. this creates the need for frequency calibration to determine the correct frequency band given a desired output frequency. the frequency calibration routine is activated any time that the r0 register is programmed with the fcal_en = 1. it is important that a valid oscin signal must present before vco calibration begins. the vco also has an internal amplitude calibration algorithm to optimize the phase noise which is also activated any time the r0 register is programmed. the optimum internal settings for this are temperature dependent. if the temperature is allowed to drift too much without being re-calibrated, some minor phase noise degradation could result. the maximum allowable drift for continuous lock, t cl , is stated in the electrical specifications. for this device, a number of 125 c means the device never loses lock if the device is operated under recommended operating conditions.
26 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated the LMX2594 allows the user to assist the vco calibration. in general, there are three kinds of assistance, as shown in table 5 : table 5. assisting the vco calibration speed assistance level description programmable settings no assist user does nothing to improve vco calibration speed. quick_recal_en=0 partial assist upon every frequency change, before the fcal_en bit is checked, the user provides the initial starting point for the vco core (vco_sel), band (vco_capctrl_strt), and amplitude (vco_daciset_strt) based on table 6 . quick_recal_en=0 close frequency assist upon initialization of the device, user enables quick_recal_en bit. the vco uses the current vco_capctrl and vco_ampcal settings as the initial starting point. quick_recal_en=1 full assist the user forces the vco core (vco_sel), amplitude settings (vco_daciset), and frequency band (vco_capctrl) and manually sets the value. vco_sel_force=1 vco_daciset_force=1 vco_capctrl_force=1 to do the partial assist for the vco calibration, follow this procedure: 1. determine vco core find a vco core that includes the desired vco frequency. if at the boundary of two cores, choose based on phase noise or performance. 2. calculate the vco capcode as follows vco_capctrl_strt = round (c coremin ? (c coremin ? c coremax ) (f vco ? f coremin ) / (f coremax ? f coremin )) 3. get the ampcal setting from the table vco_ampcal = round (a coremin + (a coremax ? a coremin ) (f vco ? f coremin )/(f coremax ? f coremin )) table 6. vco core ranges vco core f coremin f coremax c coremin c coremax a coremin a coremax vco 1 7500 8600 164 12 299 240 vco 2 8600 9800 165 16 356 247 vco 3 9800 10800 158 19 324 224 vco 4 10800 12000 140 0 383 244 vco 5 12000 12900 183 36 205 146 vco 6 12900 13900 155 6 242 163 vco 7 13900 15000 175 19 323 244 space note in the range of 11900 to 12100 mhz, vco assistance cannot be used, and the settings must be vco_sel = 4, vco_daciset_strt = 300, and vco_capctrl_strt = 1. outside this range, in the partial assist for the vco calibration, the vco calibration is run. this means that if the settings are incorrect, the vco still locks with the correct settings; the only consequence is that the calibration time might be a little longer. the closer the calibration settings are to the true final settings, the faster the vco calibration will be.
27 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.6.2 determining the vco gain the vco gain varies between the seven cores and is the lowest at the lowest end of the band and highest at the highest end of each band. for a more accurate estimation, use table 7 : table 7. vco gain f1 f2 kvco1 kvco2 7500 8600 79 113 8600 9800 81 99 9800 10800 88 130 10800 12000 182 225 12000 12900 195 250 12900 13900 250 250 based in this table, the vco gain can be estimated for an arbitrary vco frequency of f vco as: kvco = kvco1 + (kvco2-kvco1) (f vco ? f1) / (f2 ? f1) (4) 7.3.7 channel divider to go below the vco lower bound of 7.5 ghz, the channel divider can be used. the channel divider consists of four segments, and the total division value is equal to the multiplication of them. therefore, not all values are valid. figure 19. channel divider when the channel divider is used, there are limitations on the values. table 8 shows how these values are implemented and which segments are used. table 8. channel divider segments equivalent division value frequency limitation outmin (mhz) outmax (mhz) chdiv[4:0] seg0 seg1 seg2 seg3 2 none 3750 7500 0 2 1 1 1 4 1875 3750 1 2 2 1 1 6 1250 2500 2 2 3 1 1 divide by 2 or 3 divide by 2,4,6,8 divide by 2,4,6,8,16 mux mux rfouta vco mux rfoutb 1/2
28 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 8. channel divider segments (continued) equivalent division value frequency limitation outmin (mhz) outmax (mhz) chdiv[4:0] seg0 seg1 seg2 seg3 8 f vco 10 ghz 937.5 1250 3 2 2 2 1 12 625 833.333 4 2 3 2 1 16 468.75 625 5 2 2 4 1 24 312.5 416.667 6 2 2 6 1 32 234.375 312.5 7 2 2 8 1 48 125.25 208.333 8 2 3 8 1 64 117.1875 156.25 9 2 2 8 2 72 104.157 138.889 10 2 3 6 2 96 78.125 104.167 11 2 3 8 2 128 58.594 78.125 12 2 2 8 4 192 39.063 52.083 13 2 2 8 6 256 29.297 39.063 14 2 2 8 8 384 19.531 26.042 15 2 3 8 8 512 14.648 19.531 16 2 2 8 16 768 9.766 13.021 17 2 3 8 16 invalid n/a n/a n/a 18-31 n/a n/a n/a n/a the channel divider is powered up whenever an output (outx_mux) is selected to the channel divider or sysref, regardless of whether it is powered down or not. when an output is not used, ti recommends selecting the vco output to ensure that the channel divider is not unnecessarily powered up. table 9. channel divider outa mux outb mux channel divider channel divider x powered up x channel divider or sysref powered up all other cases powered down 7.3.8 output buffer the rf output buffer type is open collector so it requires an external pullup to vcc. this component may be a 50- resistor to give a nice 50- output impedance, or an inductor. the inductor has poor output impedance, but allows higher output power. the output power can be programmed to various levels or disabled while still keeping the pll in lock. if using a resistor, limit outx_pwr setting to 40; higher than this tends to actually reduce power. 7.3.9 powerdown modes the LMX2594 can be powered up and down using the ce pin or the powerdown bit. when the device comes out of the powered down state, either by resuming the powerdown bit to zero or by pulling back ce pin high (if it was powered down by ce pin), register r0 must be programmed with fcal_en high again to re-calibrate the device. 7.3.10 phase synchronization 7.3.10.1 general concept the sync pin allows one to synchronize the LMX2594 such that the delay from the rising edge of the oscin signal to the output signal is deterministic. initially, the devices are locked to the input, but are not synchronized. the user sends a synchronization pulse that is reclocked to the next rising edge of the oscin pulse. after a given time, t 1 , the phase relationship from oscin to f out will be deterministic. this time is dominated by the sum of the vco calibration time, the analog setting time of the pll loop, and the mash_rst_cnt if used in fractional mode.
29 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated figure 20. devices are now synchronized to oscin signal when the sync feature is enabled, part of the channel divide is included in the feedback path. table 10. included divide outa_mux / outb_mux channel divider included divide neither one has the channel divider or sysref selected x none at least one is selecting the channel divider or sysref divisible by 3, but not 24 or 192 seg0 seg1 = 6 all other values seg0 seg1 = 4 figure 21. phase sync diagram 7.3.10.2 categories of applications for sync the requirements for sync depend on certain setup conditions. in cases that the sync is not timing critical, it can be done through software by toggling the vco_phase_sync bit from 0 to 1. when it is timing critical, then it must be done through the pin and the setup and hold times for the oscin pin are critical. the figure 22 gives the different categories. charge pump n divider doubler r divider x m pre-r divider i external loop filter oscin rfouta mux mux seg0 seg1 seg3 seg4 rfoutb device 1 device 2 sync f osc ... ... ... ... t 1 t 2
30 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated figure 22. determining the sync category f out % f osc = 0 ? start category 1 x sync mode not required at all x no limitations on f osc category 2 x sync required x sync timing not critical x no limitations on f osc category 3 x sync required x sync timing critical x limitations on f osc chdiv <512 ? yes category 4 device can not be reliably used in sync mode m = 1 ? chdiv = 1,2,4, 6 ? yes yes yes yes no no no no no chdiv<512 this means the channel divider after the vco is less than 512 m = 1 m is the product of any input path multiplication due to the osc_2x bit and mult word. if neither of these are used, m=1. f out % f osc = 0 this means that the output frequency (f out ) is an integer multiple of the input frequency (f osc ) chdiv = 1,2,4,6 this means the channel divider after the vco is either bypassed,2,4, or 6. in this case, sync mode will put it in the loop. chdiv = 1,2,4,6 ? f out %( d | ( osc )=0 yes chdiv = 1,2,4,6 this means the channel divider after the vco is either bypassed,2,4, or 6. in this case, sync mode will put it in the loop. no f out % ( d | ( osc )= 0 m is the product of any input multiplication. this requirement is testing if the output frequency is a multiple of the highest frequency in the input path. integer mode ? no yes integer mode this is asking if the device is in integer mode, which would mean the fractional numerator is zero. chdiv=1? no category 1 x sync mode required x no software/pin sync pulse required
31 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.10.3 procedure for using sync this procedure must be used to put the device in sync mode. 1. use the flowchart to determine the sync category. 2. make determinations for oscin and using sync based on the category ( a) if category 4, sync cannot be performed in this setup. ( b) if category 3, ensure that the maximum f osc frequency for sync is not violated and there are hardware accommodations to use the sync pin. 3. if the channel divide is used, determine the included channel divide value which will be 2 seg0 of the channel divide: ( a) if neither outa_mux nor outb_mux is selected to channel divider, then the included divide is one. ( b) if one of them is, then the included channel divide value will be 2 seg0. 4. if not done already, divide the n divider and fractional values by the included channel divide to account for the included channel divide. 5. program the device with the vco_phase_sync = 1. note that this does not count as applying a sync to device (for category 2). 6. apply the sync, if required ( a) if category 2, vco_phase_sync can be toggled from 0 to 1. alternatively, a rising edge can be sent to the sync pin and the timing of this is not critical. ( b) if category 3, the sync pin must be used, and the timing must be away from the rising edge of the oscin signal. 7.3.10.4 sync input pin the sync input pin can be driven either in cmos or lvds mode. however, if not using sync mode (vco_phase_sync = 0), then the inpin_ignore bit must be set to one, otherwise it causes issues with lock detect. if the pin is desired for to be used and vco_phase_sync=1, then set inpin_ignore = 0. lvds or cmos mode may be used. lvds works to 250 mvpp, but is not ensured in production. 7.3.11 phase adjust the LMX2594 can use the sigma-delta modulator to adjust the output signal phase with respect to the input reference. the phase shift every time you write the value of mash seed is: phase shift in degrees = 360 ( mash_seed / pll_den) ( includeddivide/chdiv ) (5) example: mash seed = 1 denominator = 12 channel divider = 16 phase shift ( vco_phase_sync=1) = 360 (1/12) (1/16) = 1.875 degrees phase shift (vco_phase_sync=1) = 360 (1/12) (4/16) = 7.5 degrees phase shift can be done with a frac_num=0, but frac_order must be greater than zero. in the case of one output being set to the vco and the other output unused, the unused output can powered down but directed to the channel divider to put part of this in the loop, which can sometimes be used to create a fraction. for the phase adjust, the condition pll_den > pll_num + mash_seed must be satisfied. 7.3.12 ramping function the LMX2594 supports the ability to make ramping waveforms using manual mode or automatic mode. in manual mode, the user defines a step and uses the rampclk and rampdir pins to create the ramp. in automatic mode, the user sets up the ramp with up to two linear segments in advance and the device automatically creates this ramp. table 11 fields apply in both automatic mode and manual pin mode.
32 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 11. ramping field descriptions field programming description general commands ramp_en 0 = disabled 1 = enabled ramp_en must be 1 for any ramping functions to work. ramp_manual 0 = automatic ramping mode 1 = manual pin ramping mode in automatic ramping mode, the ramping is automatic and the clock is based on the phase detector. in manual pin ramping mode, the clock is based on rising edges on the rampclk pin. rampx_inc 0 to 2 30 ? 1 this is the amount the fractional numerator is increased for each phase detector cycle in the ramp. rampx_dly 0 to 65535 this is the length of the ramp in phase detector cycles. dealing with vco calibration ramp_thresh 0 to 2 32 whenever the fractional numerator changes this much (either positive or negative) because the vco was last calibrated, the vco is forced to recalibrate. ramp_trig_cal 0 = disabled 1 = enabled when enabled, the vco is forced to re-calibrate at the beginning each ramp. this only applies in automatic ramping mode. pll_den 4294967295 in ramping mode, the denominator must be fixed to this forced value of 2 32 ? 1. however, the effective denominator in ramping mode is 2 24 . ld_dly 0 this must be zero to avoid interfering with calibration. ramp limits ramp_limit_low ramp_limit_high 0 to 2 31 2 ? s complement of the total value of the ramp low and high limits can never go beyond. if this value is exceeded, then the frequency is limited. table 12. general restrictions for ramping rule restriction explanation phase detector frequency f osc / 2 cal_clk_div f pd 125 mhz minimum phase detector frequency when ramping the phase detector frequency cannot be less than the state machine clock frequency. the state machine clock frequency is calculated from expression on the left-hand side of the inequality. this is satisfied provided there is no division in the input path. however, if the pll r divider is used, it is necessary to adjust cal_clk_div to satisfy this constraint. also, this implies a maximum total division in the input path of 8. maximum phase detector frequency ti recommends that phase-detector frequency be less or equal than 125 mhz because if the phase detector frequency is too high, it can lead to distortion in the ramp. higher phase-detector frequency frequencies may be possible, but this distortion is application specific. 7.3.12.1 manual pin ramping manual pin ramping is enabled by setting ramp_en = 1 and ramp_mode = 1. in this mode, the ramp is clocked by rising edges applied to the rampclk pin, and the rampdir pin controls the size of the change. if a rising edge is seen on the rampclk pin while the vco is calibrating, then this rising edge is ignored. the frequency for the rampclk must be limited to a frequency of 250 khz or less, and the rising edge of the rampdir signal must be targeted to the falling edge of the rampclk pin. table 13. ramp_inc rampdir pin step size low add ramp0_inc high add ramp1_inc
33 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.12.1.1 manual pin ramping example in this ramping example, assume that we want to use the pins for up/down control of the ramp for 10 mhz steps and the phase detector is 100 mhz. table 14. step ramping example field programming description ramp_en 1 = enabled ramp_manual 1 = manual pin ramping mode ramp0_inc 1677722 (10 mhz )/ (100 mhz) 16777216 = 1677722 2 ? s complement = 1677722 ramp1_inc 1072064102 ( ? 10 mhz )/ (100 mhz) 16777216 = ? 1677722 2 ? s complement = 2^30 ? 1677722 = 1072064102 ramp_trig_cal 1 re-calibrate at every clock cycle figure 23. step ramping example output frequency time time time rampclk/trig1 pin rampdir/trig2 pin
34 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.12.2 automatic ramping automatic ramping is enabled when ramp_en=1 and ramp_mode = 0. the action of programming fcal = 1 starts the ramping. in this mode, there are two ramps that one can set the length and frequency change. in addition to this, there are ramp limits that can be used to create more complicated waveforms. automatic ramping can really be divided into two classes depending on if the vco must calibrate in the middle of the ramping waveform or not. if the vco can go the entire range without calibrating, this is calibration-free ramping, which is shown in typical characteristics . note that this range is less at hot temperatures and for lower frequency vcos. this range is not ensured, so margin must be built into the design. for waveforms that are not calibration free, the slew rate of the ramp must be kept less than 250 khz/ s. also, for all automatic ramping waveforms, be aware that there is a very small phase disturbance as the vco crosses over the integer boundary, so one might consider using the input multiplier to avoid these or timing the vco calibrations at integer boundaries. table 15. automatic ramping field descriptions field programming description ramp_dly 0 = one clock cycle 1 = two clock cycles normally the ramp clock is equal to the phase detector frequency. when this feature is enabled, it reduces the ramp clock by a factor of 2. ramp0_len ramp1_len 0 to 65535 this is the length of the ramp in clock cycles. note that the time that the vco is calibrating is added to this time. ramp0_inc ramp1_inc 0 to 2 30 2 ? s complement of the value for the ramp increment. ramp0_next ramp1_next 0 = ramp0 1 = ramp1 defines which ramp comes after the current ramp. ramp0_next_trig ramp1_next_trig 0 = timeout counter 1 = trigger a 2 = trigger b 3 = reserved determines what triggers the action of the next ramp occurring. ramp_trig_a ramp_trig_b 0 = disabled 1 = rampclk rising edge 2 = rampdir rising edge 4 = always triggered 9 = rampclk falling edge 10 = rampdir falling edge all other states = invalid this field defines what the ramp trigger is. ramp0_rst ramp1_rst 0 = disabled 1 = enabled enabling this bit causes the ramp to reset to the original value when the ramping started. this is useful for roundoff errors. ramp_burst_count 0 to 8191 this is the number the ramping pattern repeats and only applies for a terminating ramping pattern. ramp_burst_trig 0 = ramp transition 1 = trigger a 2 = trigger b 3 = reserved this defines what causes the ramp_count to increment.
35 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.12.2.1 automatic ramping example (triangle wave) suppose user wants to generate a sawtooth ramp that goes from 8 to 10 ghz in 2 ms (including calibration breaks) with a phase-detector frequency of 50 mhz. divide this into segments of 50 mhz where the vco ramps for 25 s, then calibrates for 25 s, for a total of 50 s. there would therefore be 40 such segments which span over a 2-ghz range and would take 2 ms, including calibration time. table 16. sawtooth ramping example field programming description ramp_en 1 = enabled ramp_manual 0 = automatic ramping mode ramp_trig_cal 0 = disabled ramp_thresh 8388608 50 mhz / 50 mhz 2 24 = 16777216 ramp_dly 0 = 1 clock cycle rampx_len 13422 1000 s 50 mhz = 50000 ramp0_inc 13422 (2000 mhz) / (50 mhz) 2 24 / 50000 = 13422 ramp1_inc 1073740146 ( ? 2000 mhz) / (50 mhz) 2 24 / 50000 = ? 13422 2 ? s complement = 2 30 ? 13422 = 1073728402 ramp0_next 1 = ramp1 ramp1_next 0 = ramp0 rampx_next_trig 0 = timeout counter ramp_trig_x 0 = disabled ramp0_rst 1 = enabled not necessary, but good practice to reset. ramp1_rst 0 = disabled do not reset this, or ramp does not work. ramp_burst_count 0 ramp_burst_trig 0 = ramp transition figure 24. triangle waveform example time 10 ghz 8 ghz ramp 0 2 ms ramp0 ramp 1 1 ms
36 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.13 sysref the LMX2594 can used to a sysref output signal that synchronized to the output with a programmable delay. this output can be a single pulse, series of pulse, or a continuous stream of pulses. to use the sysref capability, the pll must be in sync mode with vco_phase_sync = 1. figure 25. sysref setup as figure 25 shows, the sysref feature shares parts of the channel divide and puts a pre-divider in front of the n divider; this must be taken into consideration when using the sysref feature. when configured for this mode, a rising edge is sent to the sysrefreq pin, which causes the device to output either a single pulse or a series of pulses to the rfoutb pins. these pulses are synchronous with the rfouta signal with an adjustable delay. table 17. sysref setup parameter min typ max unit f vco 7.5 15 ghz f interpolator 0.8 1.5 ghz sysref_div_ch (part of channel divider) 2, 4, or 6 sysref_div_pre 1, 2, or 4 sysref_div 1 to 2047, but maybe not all values can be used f interpolator f presysref = f vco /(sysref_div_ch sysref_div_pre) f sysref f sysref = f interpolator / (2 sysref_div) delay step size 9 ps pulses for pulsed mode (sysref_pulse_cnt) 0 15 n/a the delay can be programmed using the jesd_dac1_ctrl, jesd_dac2_ctrl, jesd_dac3_ctrl, and jesd_dac4_ctrl words. by concatenating these words into a larger word called "sysrefphaseshift", the relative delay can be found. the sum of these words should always be 63. part of channel divider (sysref_div_ch) rest of channel divider rfouta divider (sysref_div) rfoutb to phase detector delay circuit f vco f out f sysref divider (sysref_div_pre) f presysref f sysref mux n divider
37 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 18. sysref delay sysref delay delay jesd_dac1 jesd_dac2 jesd_dac3 jesd_dac4 0 minimum 36 27 0 0 ... 0 0 36 0 63 0 0 37 62 1 0 0 ... 99 0 0 63 0 100 0 0 62 1 ... 161 0 0 1 62 162 0 0 0 63 163 1 0 0 62 224 63 0 0 0 225 62 1 0 0 247 maximum 41 22 0 0 > 247 invalid invalid invalid invalid invalid 7.3.13.1 programmable fields table 19 has the programmable fields for the sysref functionality. table 19. sysref programming fields field programming default description sysref_en 0 = disabled 1 = enabled 0 enables the sysref mode sysref_div_pre 1: div1 2: div2 4: div4 other states: invalid the output of this divider is the f presysref . sysref_repeat 0 = generator 1 = repeater 0 in generator mode, the device creates a series of sysref pulses. in repeater mode, sysref pulses are generated with the sysrefreq pin. sysref_pulse 0 = continuous mode 1 = pulsed mode 0 continuous mode continuously makes sysref pulses, where pulsed mode makes a series of sysref_pulse_cnt pulses sysref_pulse_cnt 0 to 15 4 in the case of using pulsed mode, this is the number of pulses. setting this to zero is an allowable, but not practical state. sysref_div 170 to 2047 0 the sysref frequency is at the vco frequency divided by this value.
38 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.13.2 input and output pin formats 7.3.13.2.1 input format for sync and sysref pins these pins are single-ended but a differential signal can be converted to drive them. in the lvds mode, if the inpin_fmt is set to lvds mode, then the bias level can be adjusted with inpin_lvl and the hysteresis can be adjusted with inpin_hyst. figure 26. driving sync/sysref with differential signal 7.3.13.2.2 sysref output format the sysref output comes in differential format through rfoutb. this will have a minimum voltage of about 2.3 v and a maximum of 3.3 v. if dc coupling cannot be used, there are two strategies for ac coupling. figure 27. sysref output 1. send a series of pulses to establish a dc-bias level across the ac-coupling capacitor. 2. establish a bias voltage at the data converter that is below the threshold voltage by using a resistive divider. 7.3.13.3 examples the sysref can be used in a repeater mode, which just echos the input, after being reclocked to oscin and then rfout, or it can be used in a repeater. in either mode, there is a phase adjustment with resolution of 1/16 of the output phase up to a maximum of 1 ns. in repeater mode, it can repeat 1,2,4,8, or infinite (continuous) pulses. the frequency for repeater mode is equal to the rfout frequency divided by the sysref divider. data converter LMX2594 sysrefoutp sysrefoutn 3.3 v 3.3 v LMX2594 sync v min v max
39 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated figure 28. sysref out in repeater mode figure 29. figure 1. sysref out in pulsed/continuous mode LMX2594 rfoutap rfoutan rfoutbp/sysrefoutp rfoutbp/sysrefoutn sync oscinp oscinn sysrefreq LMX2594 rfoutap rfoutan rfoutbp/sysrefoutp rfoutbp/sysrefoutn sync oscinp oscinn sysrefreq t t t 1 LMX2594 rfoutap rfoutan rfoutbp/sysrefoutp rfoutbp/sysrefoutn sync oscinp oscinn sysrefreq LMX2594 rfoutap rfoutan rfoutbp/sysrefoutp rfoutbp/sysrefoutn sync oscinp oscinn sysrefreq t 2 t 2 t 1
40 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.3.13.4 sysref procedure to use sysref, do the these steps: 1. put the device in sync mode using the procedure already outlined. 2. figure out the included channel divide the same way it is done for sync mode. 3. calculate the sysref_div_pre value such that the interpolator frequency (f interpolator ) is in the range of 800 to 1500 mhz. f interpolator = f vco /includeddivide/sysref_div_pre 4. if using master mode (sysref_repeat=0), ensure sysrefreq pin is high, ensure the sysrefreq pin is high. 5. if using repeater mode (sysref_repeat=1), set up the pulse count if desired. pulses are created by toggling the sysrefreq pin. 6. adjust the delay between the rfouta and rfoutb signal using the jesd_dacx_ctl fields. 7.3.14 sysrefreq pin the sysrefreq pin can be used in cmos all the time, or lvds mode is also optional if sysref_repeat = 1. lvds mode cannot be used in master mode. 7.4 device functional modes although there is a vast number of ways to configure this device, there is really only one functional. table 20. device functional modes mode description software settings reset registers are held in their reset state. this device does have a power on reset, but it is good practice to also do a software reset if there is any possibility of noise on the programming lines, especially if there is sharing with other devices. also realize that there are registers not disclosed in the data sheet that are reset as well. reset = 1, powerdown = 0 powerdown device is powered down. powerdown = 1 or ce pin = low normal operating mode this is used with at least one output on as a frequency synthesizer. sync mode this is used where part of the channel divider is in the feedback path to ensure deterministic phase. vco_phase_sync = 1 sysref mode in this mode, rfoutb is used to generate pulses for sysref. vco_phase_sync =1, sysref_en = 1
41 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.5 programming the LMX2594 is programmed using 24-bit shift registers. the shift register consists of a r/w bit (msb), followed by a 7-bit address field and a 16-bit data field. for the r/w bit, 0 is for write, and 1 is for read. the address field address[6:0] is used to decode the internal register address. the remaining 16 bits form the data field data[15:0]. while csb is low, serial data is clocked into the shift register upon the rising edge of clock (data is programmed msb first). when csb goes high, data is transferred from the data field into the selected register bank. see figure 1 for timing details. 7.5.1 recommended initial power-up sequence for the most reliable programming, ti recommends this procedure: 1. apply power to device. 2. program reset = 1 to reset registers. 3. program reset = 0 to remove reset. 4. program registers as shown in the register map in reverse order from highest to lowest. 5. program register r0 one additional time with fcal_en = 1 to ensure that the vco calibration runs from a stable state. 7.5.2 recommended sequence for changing frequencies the recommended sequence for changing frequencies is as follows: 1. change the n divider value. 2. program the pll numerator and denominator. 3. program fcal_en (r0[3]) = 1. 7.6 register maps and descriptions note that for registers that have numbers, but defined programmable bits, it is necessary to program these values just as shown in the register map. registers must be programmed from highest to lowest (r0 last)
LMX2594 snas696 ? march 2017 www.ti.com 42 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 21. full register map r/w a6 a5 a4 a3 a2 a1 a0 d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r0 0 0 0 0 0 0 0 0 ramp _en vco _ph ase _sy nc_ en 1 0 0 1 out _mu te fcal_hpf d_adj fcal_lpfd _adj 1 fca l _en mux out _ld_ sel res et pow erd own r1 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 1 cal_clk_div r2 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 r3 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 1 0 0 0 0 1 0 r4 0 0 0 0 0 1 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 0 1 1 r5 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 1 1 0 0 1 0 0 0 r6 0 0 0 0 0 1 1 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0 1 0 r7 0 0 0 0 0 1 1 1 0 out _fo rce 0 0 0 0 0 0 1 0 1 1 0 0 1 0 r8 0 0 0 0 1 0 0 0 0 vco _da cise t_f orc e 1 0 vco _ca pct rl_f orc e 0 0 0 0 0 0 0 0 0 0 0 r9 0 0 0 0 1 0 0 1 0 0 0 osc _2x 0 1 1 0 0 0 0 0 0 1 0 0 r10 0 0 0 0 1 0 1 0 0 0 0 1 mult 1 0 1 1 0 0 0 r11 0 0 0 0 1 0 1 1 0 0 0 0 pll_r 1 0 0 0 r12 0 0 0 0 1 1 0 0 0 1 0 1 pll_r_pre r13 0 0 0 0 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r14 0 0 0 0 1 1 1 0 0 0 0 1 1 1 1 0 0 cpg 0 0 0 0 r15 0 0 0 0 1 1 1 1 0 0 0 0 0 1 1 0 0 1 0 0 1 1 1 1 r16 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 vco_daciset r17 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 vco_daciset_strt r18 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 1 0 0 r19 0 0 0 1 0 0 1 1 0 0 1 0 0 1 1 1 vco_capctrl r20 0 0 0 1 0 1 0 0 1 0 vco_sel vco _sel _fo rce 0 0 0 1 0 0 1 0 0 0 r21 0 0 0 1 0 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 r22 0 0 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
LMX2594 www.ti.com snas696 ? march 2017 43 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 21. full register map (continued) r/w a6 a5 a4 a3 a2 a1 a0 d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r23 0 0 0 1 0 1 1 1 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 r24 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 0 0 0 1 1 0 1 0 r25 0 0 0 1 1 0 0 1 0 0 0 0 0 1 1 0 0 0 1 0 0 1 0 0 r26 0 0 0 1 1 0 1 0 0 0 0 0 1 1 0 1 1 0 1 1 0 0 0 0 r27 0 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 r28 0 0 0 1 1 1 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 0 0 r29 0 0 0 1 1 1 0 1 0 0 1 1 0 0 0 1 1 0 0 0 1 1 0 0 r30 0 0 0 1 1 1 1 0 0 0 1 1 0 0 0 1 1 0 0 0 1 1 0 0 r31 0 0 0 1 1 1 1 1 0 1 0 0 0 0 1 1 1 1 1 0 1 1 0 0 r32 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 1 0 0 1 1 r33 0 0 1 0 0 0 0 1 0 0 0 1 1 1 1 0 0 0 1 0 0 0 0 1 r34 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pll_n[18:16] r35 0 0 1 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 r36 0 0 1 0 0 1 0 0 pll_n r37 0 0 1 0 0 1 0 1 mash_see d_en 0 pfd_dly_sel 0 0 0 0 0 1 0 0 r38 0 0 1 0 0 1 1 0 pll_den[31:16] r39 0 0 1 0 0 1 1 1 pll_den[15:0] r40 0 0 1 0 1 0 0 0 mash_seed[31:16] r41 0 0 1 0 1 0 0 1 mash_seed[15:0] r42 0 0 1 0 1 0 1 0 pll_num[31:16] r43 0 0 1 0 1 0 1 1 pll_num[15:0] r44 0 0 1 0 1 1 0 0 0 0 outa_pwr out b_p d out a_p d mas h_r ese t_n 0 0 mash_order r45 0 0 1 0 1 1 0 1 1 1 0 outa_mux out_iset 0 1 1 outb_pwr r46 0 0 1 0 1 1 1 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 outb_mux r47 0 0 1 0 1 1 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 r48 0 0 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 r49 0 0 1 1 0 0 0 1 0 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 r50 0 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r51 0 0 1 1 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 r52 0 0 1 1 0 1 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 r53 0 0 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
LMX2594 snas696 ? march 2017 www.ti.com 44 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 21. full register map (continued) r/w a6 a5 a4 a3 a2 a1 a0 d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r54 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r55 0 0 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r56 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r57 0 0 1 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 r58 0 0 1 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 r59 0 0 1 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ld_t ype r60 0 0 1 1 1 1 0 0 ld_dly r61 0 0 1 1 1 1 0 1 0 0 0 0 0 0 0 0 1 0 1 0 1 0 0 0 r62 0 0 1 1 1 1 1 0 0 0 0 0 0 0 1 1 0 0 1 0 0 0 1 0 r63 0 0 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r64 0 1 0 0 0 0 0 0 0 0 0 1 0 0 1 1 1 0 0 0 1 0 0 0 r65 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r66 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 1 1 1 1 1 0 1 0 0 r67 0 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r68 0 1 0 0 0 1 0 0 0 0 0 0 0 0 1 1 1 1 1 0 1 0 0 0 r69 0 1 0 0 0 1 0 1 mash_rst_count[31:16] r70 0 1 0 0 0 1 1 0 mash_rst_count[15:0] r71 0 1 0 0 0 1 1 1 0 0 0 0 0 0 0 0 sysref_div_pre sys ref _pul se sys ref _en sys ref _re pea t 0 1 r72 0 1 0 0 1 0 0 0 0 0 0 0 0 sysref_div r73 0 1 0 0 1 0 0 1 0 0 0 0 jesd_dac2_ctrl jesd_dac1_ctrl r74 0 1 0 0 1 0 1 0 sysref_pulse_cnt jesd_dac4_ctrl jesd_dac3_ctrl r75 0 1 0 0 1 0 1 1 0 0 0 0 1 chdiv 0 0 0 0 0 0 r76 0 1 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 r77 0 1 0 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r78 0 1 0 0 1 1 1 0 0 0 0 0 ram p_t hre sh[3 2] 0 quic k_r eca l_en vco_capctrl_strt 1 r79 0 1 0 0 1 1 1 1 ramp_thresh[31:16] r80 0 1 0 1 0 0 0 0 ramp_thresh[15:0]
LMX2594 www.ti.com snas696 ? march 2017 45 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 21. full register map (continued) r/w a6 a5 a4 a3 a2 a1 a0 d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r81 0 1 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ram p_li mit_ high [32] r82 0 1 0 1 0 0 1 0 ramp_limit_high[31:16] r83 0 1 0 1 0 0 1 1 ramp_limit_high[15:0] r84 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ram p_li mit_ low [32] r85 0 1 0 1 0 1 0 1 ramp_limit_low[31:16] r86 0 1 0 1 0 1 1 0 ramp_limit_low[15:0] r87 0 1 0 1 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r88 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r89 0 1 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r90 0 1 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r91 0 1 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r92 0 1 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r93 0 1 0 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r94 0 1 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r95 0 1 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r96 0 1 1 0 0 0 0 0 ramp_bur st_en ramp_burst_count 0 0 r97 0 1 1 0 0 0 0 1 ramp0_rs t 0 0 0 1 ramp_trigb ramp_triga 0 ramp_bur st_trig r98 0 1 1 0 0 0 1 0 ramp0_inc[29:16] ram p0_f l ram p0_d ly r99 0 1 1 0 0 0 1 1 ramp0_inc[15:0] r100 0 1 1 0 0 1 0 0 ramp0_len r101 0 1 1 0 0 1 0 1 0 0 0 0 0 0 0 0 0 ram p1 _dly ram p1 _rs t ram p0 _ne xt 0 0 ramp0 _next _trig r102 0 1 1 0 0 1 1 0 0 0 ramp1_inc[29:16] r103 0 1 1 0 0 1 1 1 ramp1_inc[15:0]
LMX2594 snas696 ? march 2017 www.ti.com 46 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 21. full register map (continued) r/w a6 a5 a4 a3 a2 a1 a0 d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r104 0 1 1 0 1 0 0 0 ramp1_len r105 0 1 1 0 1 0 0 1 ramp_dly_cnt ram p_m anu al ram p1_n ext 0 0 ramp1_ne xt_trig r106 0 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 ram p_t rig_ cal 0 ramp_scale_co unt r107 0 1 1 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r108 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r109 0 1 1 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r110 0 1 1 0 1 1 1 0 0 0 0 0 0 rb_ld_vtu ne 0 rb_vco_sel 0 0 0 0 0 r111 0 1 1 0 1 1 1 1 0 0 0 0 0 0 0 0 rb_vco_capctrl r112 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 rb_vco_daciset
47 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.1 general registers r0, r1, & r7 figure 30. registers excluding address addre ss d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r0 ramp _en vco_ phas e_sy nc_e n 1 0 0 1 out_ mute fcal_hpfd_ adj fcal_lpfd_ adj 1 fcal _en mux out_ ld_s el rese t pow erdo wn r1 0 0 0 0 1 0 0 0 0 0 0 0 1 cal_clk_div r7 0 out_ forc e 0 0 0 0 0 0 1 0 1 1 0 0 1 0 legend: r/w = read/write; r = read only; -n = value after reset table 22. field descriptions location field type reset description r0[15] ramp_en r/w 0 0 : disable frequency ramping mode 1 : enable frequency ramping mode r0[14] vco_phase_sync r/w 0 0 : disable phase sync mode 1 : enable phase sync mode r0[9] out_mute r/w 0 mute the outputs when the vco is calibrating. 0 : disabled. if disabled, also be sure to enable out_force 1 : enabled. if enabled, also be sure to disable out_force r0[8:7] fcal_hpfd_adj r/w set this field in accordance to the phase-detector frequency for optimal vco calibration. 0 : f pd 100 mhz 1: 100 mhz < f pd 150 mhz 2 : 150 mhz < f pd 200 mhz 3: f pd > 200 mhz r0[6:5] fcal_lpfd_adj r/w 0 set this field in accordance to the phase detector frequency for optimal vco calibration. 0: f pd 10 mhz 1: 10 mhz > f pd 5 mhz 2: 5 mhz > f pd 2.5 mhz 3: f pd < 2.5 mhz r0[3] fcal_en r/w 0 enablie the vco frequency calibration. also note that the action of programming this bit to a 1 activates the vco calibration r0[2] muxout_ld_sel r/w 0 selects the state of the function of the muxout pin 0: readback 1: lock detect r0[1] reset r/w 0 resets and holds all state machines and registers to default value. 0: normal operation 1: reset r0[0] powerdown r/w 0 powers down entire device 0: normal operation 1: powered down r1[2:0] cal_clk_div r/w 3 sets divider for vco calibration state machine clock based on input frequency. 0: f osc 200 mhz 1: 200 mhz < f osc 400 mhz 2: 400 mhz < f osc 800 mhz 3: f osc > 800 mhz r7[14] out_force r/w 0 works with out_mute in disabling outputs when vco calibrating.
48 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.2 input path registers figure 31. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r9 0 0 0 osc_ 2x 0 1 1 0 0 0 0 0 0 1 0 0 r10 0 0 0 1 mult 1 0 1 1 0 0 0 r11 0 0 0 0 pll_r 1 0 0 0 r12 0 1 0 1 pll_r_pre legend: r/w = read/write; r = read only; -n = value after reset table 23. field descriptions location field type reset description r9[12] osc_2x r/w 0 low=noise oscin frequency doubler. 0: disabled 1: enabled r10[11:7] mult r/w 1 programmable input frequency multiplier 0,2,,8-31: reserved 1: byapss 3: 3x ... 7: 7x r11[11:4] pll_r r/w 1 programmable input path divider after the programmable input frequency multiplier. r12[11:0] pll_r_pre r/w 1 programmable input path divider before the programmable input frequency multiplier. 7.6.3 charge pump registers (r13, r14) figure 32. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r14 0 0 0 1 1 1 1 0 0 cpg 0 0 0 0 legend: r/w = read/write; r = read only; -n = value after reset table 24. field descriptions location field type reset description r14[6:4] cpg r/w 7 effective charge-pump current. this is the sum of up and down currents. 0: 0 ma 1: 6 ma 2: reserved 3: 12 ma 4: 3 ma 5: 9 ma 6: reserved 7: 15 ma
49 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.4 vco calibration registers figure 33. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r8 0 vco_ daci set_ forc e 1 0 vco_ capc trl_ forc e 0 0 0 0 0 0 0 0 0 0 0 r16 0 0 0 0 0 0 0 vco_daciset r17 0 0 0 0 0 0 0 vco_ daci set_ strt 0 0 1 1 0 0 r19 0 0 1 0 0 1 1 1 vco_capctrl r20 1 vco_ sel_ strt _en vco_sel vco_ sel_ forc e 0 0 0 1 0 0 1 0 0 0 legend: r/w = read/write; r = read only; -n = value after reset table 25. field descriptions location field type reset description r8[14] vco_daciset_force r/w 0 this forces the vco_daciset value r8[11] vco_capctrl_force r/w 0 this forces the vco_capctrl value r16[8:0] vco_daciset r/w 128 this sets the final amplitude for the vco calibration in the case that amplitude calibration is forced. r17[8:0] vco_daciset_strt r/w 250 this sets the initial starting point for the vco amplitude calibration. r19[7:0] vco_capctrl r/w 183 this sets the final vco band when vco_capctrl is forced. r20[13:11] vco_sel r/w 7 this sets the vco that is used when vco_sel_strt_en=1 or vco_sel_force=1 0: not used 1: vco1 2: vco2 3: vco3 4: vco4 5: vco5 6: vco6 7: vco7 r20[10] vco_sel_force r/w 0 this forces the vco to use the core specified by vco_sel. it is intended mainly for diagnostic purposes. 0: disabled (recommended) 1: enabled
50 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.5 n divider, mash, and output registers figure 34. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r34 0 0 0 0 0 0 0 0 0 0 0 0 0 pll_n[18:16] r36 pll_n r37 mash _see d_en 0 pfd_dly_sel 0 0 0 0 0 1 0 0 r38 pll_den[31:16] r39 pll_den[15:0] r40 mash_seed[31:16] r41 mash_seed[15:0] r42 pll_num[31:16] r43 pll_num[15:0] r44 0 0 outa_pwr outb _pd outa _pd mash _res et_n 0 0 mash_order r45 1 1 0 outa_mux out_iset 0 1 1 outb_pwr r46 0 0 0 0 0 1 1 1 1 1 1 1 1 1 outb_mux legend: r/w = read/write; r = read only; -n = value after reset table 26. field descriptions location field type reset description r34[2:0] r36[15:0] pll_n r/w 100 the pll_n divider value is in the feedback path and divides the vco frequency. 0: disabled 1: enabled r37[15] mash_seed_en r/w 0 enabling this bit allows the mash_seed to be applied to shift the phase at the output or optimize spurs. r37[13:8] pfd_dly_sel r/w 2 the pfd_dly_sel must be adjusted in accordance to the n divider value. this is with the functional description for the n divider. r38[15:0] r39[15:0] pll_den r/w 42949672 95 the fractional denominator. r40[15:0] r41[15:0] mash_seed r/w 0 the initial state of the mash engine first accumulator. can be used to shift phase or optimize fractional spurs. every time the mash_seed field is programmed, it adds this mash seed to the existing one. to reset it, use the mash_reset_n bit. r42[15:0] r43[15:0] pll_num r/w 0 the fractional numerator r44[13:8] outa_pwr r/w 31 adjusts output power. higher numbers give more output power to a point, depending on the pullup component used. r44[7] outb_pd r/w 1 powers down output b 0: output b active 1: output b powered down r44[6] outa_pd r/w 0 powers down output a 0: output a active 1: output a powered down r44[5] mash_reset_n r/w 1 resets mash circuitry to an initial state 0: disabled. fractional mode enabled. 1: enabled. all fractions are ignored and mash engine is reset. r44[2:0] mash_order r/w 0 sets the mash order 0: integer mode 1: first order modulator 2: second order modulator 3: third order modulator 4: fourth order modulator 5-7: reserved
51 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 26. field descriptions (continued) location field type reset description r45[12:11] outa_mux r/w 1 selects what signal goes to rfouta 0: channel divider 1: vco 2: reserved 3: high impedance r45[10:9] out_isel r/w 0 setting to a lower value allows slightly higher output power at higher frequencies at the expense of higher current consumption. 0: maximum output power boost ... 3: no output power boost r45[5:0] outb_pwr r/w 31 output power setting for rfoutb. r46[1:0] outb_mux r/w 1 selects what signal goes to rfoutb 0: channel divider 1: vco 2: sysref 3: high impedance 7.6.6 lock detect registers figure 35. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r59 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ld_t ype r60 ld_dly legend: r/w = read/write; r = read only; -n = value after reset table 27. field descriptions location field type reset description r59[0] ld_type r/w 1 lock detect type 0: vco calibration status 1: vco calibration status and vtune r60[15:0] ld_dly r/w 1000 this is the delay added to the lock detect after the vco calibration is successful. it is in phase-detector cycles. 7.6.7 mash_reset figure 36. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r69 mash_rst_count[31:16] r70 mash_rst_count[15:0] legend: r/w = read/write; r = read only; -n = value after reset table 28. field descriptions location field type reset description r69[15:0] r70[15:0] mash_rst_count r/w 50000 if not using this device in fractional mode with vco_phase_sync=1, then this field can be set to 0. in phase- sync mode with fractions, this bit is used so that there is a delay for the vco divider after the mash is reset. this delay must be set to greater than the lock time of the pll. it does impact the latency time of the sync feature.
52 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.8 sysref registers figure 37. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r71 0 0 0 0 0 0 0 0 sysref_div_pre sysr ef_p ulse sysr ef_e n sysr ef_r epea t 0 1 r72 0 0 0 0 0 sysref_div r73 0 0 0 0 jesd_dac2_ctrl jesd_dac1_ctrl r74 sysref_pulse_cnt jesd_dac4_ctrl jesd_dac3_ctrl legend: r/w = read/write; r = read only; -n = value after reset table 29. field descriptions location field type reset description r71[7:5] stsref_div_pre r/w 4 pre divider for sysref 2: divide by 2 4: divide by 4 all other states: invalid r71[4] sysref_pulse r/w 0 enable pulser mode in master mode 0: disabled 1: enabled r71[3] sysref_en r/w 0 enable sysref r71[2] sysref_repeat r/w 0 enable repeater mode 0: master mode 1: repeater mode r72[10:0] sysref_div r/w 0 divider for the sysref fout = fin / (2 sysref_div + 4) r73[5:0] jesd_dac1_ctrl r/w 63 these are the adjustments for the delay for the sysref. two of these must be zero and the other two values must sum to 63. r73[11:6] jesd_dac2_ctrl r/w 0 r74[5:0] jesd_dac3_ctrl r/w 0 r74[11:6] jesd_dac4_ctrl r/w 0 r74[15:12] sysref_pulse_cnt r/w 0 number of pulses in pulse mode in master mode
53 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.9 channel divider registers figure 38. registers excluding address reg 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 r75 0 0 0 0 1 chdiv 0 0 0 0 0 0 legend: r/w = read/write; r = read only; -n = value after reset table 30. field descriptions location field type reset description r75[10:6] chdiv r/w 0 vco divider value 0: 2 1: 4 2: 6 3: 8 4: 12 5: 16 6: 24 7: 32 8: 48 9: 64 10: 72 11: 96 12: 128 13: 192 14: 256 15: 384 16: 512 17: 768 18-31: reserved 7.6.10 ramping and calibration fields figure 39. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r78 0 0 0 0 ramp _thr esh[3 2] 0 quic k_re cal_ en vco_capctrl_strt 1 r79 ramp_thresh[31:16] r80 ramp_thresh[15:0] legend: r/w = read/write; r = read only; -n = value after reset table 31. field descriptions location field type reset description r78[11] r79[15:0] r80[15:0] ramp_thresh r/w 0 this sets how much the ramp can change the vco frequency before calibrating. if this frequency is chosen to be f, then it is calculated as follows: ramp_thresh = ( f / f pd ) 16777216 r78[9] quick_recal_en r/w 0 causes the initial vco_core, vco_capctrl, and vco_daciset to be based on the last value. useful if the frequency change is small, as is often the case for ramping. 0: disabled 1: enabled r78[8:1] vco_capctrl_strt r/w 0 this is the capcode that is used for the calibration when vco_capctrl_strt_en = 1. smaller values yield a higher frequency band within a vco core. valid number range is 0 to 183.
54 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.11 ramping registers these registers are only relevant for ramping functions and are enabled if and only if ramp_en (r0[15]) = 1. 7.6.11.1 ramp limits figure 40. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r81 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ramp _limi t_hig h[32] r82 ramp_limit_high[31:16] r83 ramp_limit_high[15:0] r84 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ramp _limi t_lo w[32] r85 ramp_limit_low[31:16] r86 ramp_limit_low[15:0] legend: r/w = read/write; r = read only; -n = value after reset table 32. field descriptions location field type reset description r81[0] r82[15:0] r83[15:0] ramp_limit_high r/w 0 this sets a maximum frequency that the ramp can not exceed so that the vco does not get set beyond a valid frequency range. suppose f high is this frequency and f vco is the starting vco frequency then: for f max f vco : ramp_limit_high = (f high - f vco )/f pd 16777216 for f max < f vco this is not a valid condition to choose. r84[0] r85[15:0] r86[15:0] ramp_limit_low r/w 0 this sets a minimum frequency that the ramp can not exceed so that the vco does not get set beyond a valid frequency range. suppose f low is this frequency and f vco is the starting vco frequency then: for f low f vco : ramp_limit_low =2 32 - (f low - f vco ) / f pd 16777216 for f low > f vco this is not a valid condition to choose. 7.6.11.2
55 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 7.6.11.3 ramping triggers, burst mode, and ramp0_rst figure 41. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r96 ramp _bur st_e n ramp_burst_count 0 0 r97 ramp 0_rs t 0 0 0 1 ramp_trigb ramp_triga 0 ramp_burs t_trig legend: r/w = read/write; r = read only; -n = value after reset table 33. field descriptions location field type reset description r96[15] ramp_burst_en r/w 0 enables burst ramping mode. in this mode, a ramp_burst_count ramps are sent out when ramp_en is set from 0 to 1. 0: disabled 1: enabled ramp96[1 4:2] ramp_burst_count r/w 0 sets how many ramps are run in burst ramping mode. r97[15] ramp0_rst r/w 0 resets ramp0 at start of ramp to eliminate round-off errors. must only be used in automatic ramping mode. 0: disabled 1: enabled r97[6:3] ramp_triga r/w 0 multipurpose trigger a definition: 0: disabled 1: rampclk pin rising edge 2: rampdir pin rising edge 4: always triggered 9: rampclk pin falling edge 10: rampdir pin falling edge all other states: reserved r97[10:7] ramp_trigb r/w 0 multipurpose trigger b definition: 0: disabled 1: rampclk pin rising edge 2: rampdir pin rising edge 4: always triggered 9: rampclk pin falling edge 10: rampdir pin falling edge all other states: reserved r97[1:0] ramp_burst_trig r/w 0 ramp burst trigger definition that triggers the next ramp in the count. note that ramp_en starts the count, not this word. 0: disabled 1: rampclk pin rising edge 5: cmp0 detected 8: always triggered all other states: reserved 7.6.11.4 ramping configuration
56 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated figure 42. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r98 ramp0_inc[29:16] 0 ramp 0_dl y r99 ramp0_inc[15:0] r100 ramp0_len r101 0 0 0 0 0 0 0 0 0 ramp 1 _dly ramp 1 _rst ramp 0 _nex t 0 ramp 0_ next _trig ramp0_ next_trig r102 0 0 ramp1_inc[29:16] r103 ramp1_inc[15:0] r104 ramp1_len r105 ramp_dly_cnt ramp _man ual ramp 1 _nex t 0 0 ramp1_ next_trig r106 0 0 0 0 0 0 0 0 0 0 0 ramp _trig _cal 0 ramp_scale_coun t legend: r/w = read/write; r = read only; -n = value after reset table 34. field descriptions location field type reset description r98[15:2] r99[15:0] ramp0_inc r/w 0 2's complement of the amount the ramp0 is incremented in phase detector cycles. r98[0] ramp0_dly r/w 0 enabling this bit uses two clocks instead of one to clock the ramp. effectively doubling the length. 0: normal ramp length 1: double ramp length r100[15:0] ramp0_len r/w 0 length of ramp0 in phase detector cycles r101[6] ramp1_dly r/w 0 enabling this bit uses two clocks instead of one to clock the ramp. effectively doubling the length. 0: normal ramp length 1: double ramp length r101[5] ramp1_rst r/w 0 resets ramp1 to eliminate rounding errors. must be used in automatic ramping mode. 0: disabled 1: enabled r101[4] ramp0_next r/w 0 defines what ramp comes after ramp0 0: ramp0 1: ramp1 r101[1:0] ramp0_next_trig r/w 0 defines what triggers the next ramp 0: ramp0_len timeout counter 1: trigger a 2: trigger b 3: reserved r102[13:0] r103[15:0] ramp1_inc r/w 0 2's complement of the amount the ramp0 is incremented in phase detector cycles. r104[15:0] ramp1_len r/w 0 length of ramp1 in phase detector cycles r105[15:6] ramp_dly_cnt r/w 0 this is the amount of time for the vco calibration in automatic mode. if the vco calibration is less, then it is this time. if it is more then the time is the vco caliabration time. r105[5] ramp_manual r/w 0 enables manual ramping mode, otherwise automatic mode 0: automatic ramping mode 1: manual ramping mode r105[4] ramp1_next r/w 0 determines what ramp comes after ramp1: 0: ramp0 1: ramp1
57 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 34. field descriptions (continued) location field type reset description r105[1:0] ramp_next_trig r/w 0 defines what triggers the next ramp 0: ramp1_len timeout counter 1: trigger a 2: trigger b 3: reserved r106[4] ramp_trig_cal r/w 0 enabling this bit forces the vco to calibrate after the ramp. r106[2:0] ramp_scale_count r/w 7 multiplies ramp_dly count by 2 ramp_scale_count 7.6.12 readback registers figure 43. registers excluding address d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r110 0 0 0 0 0 rb_ld_ vtune 0 rb_vco_sel 0 0 0 0 0 r111 0 0 0 0 0 0 0 0 rb_vco_capctrl r112 0 0 0 0 0 0 0 rb_vco_daciset legend: r/w = read/write; r = read only; -n = value after reset table 35. field descriptions location field type reset description r110[10:9] rb_ld_vtune r 0 readback of vtune lock detect 0: unlocked (vtune low) 1: unlocked (vtune high) 2: locked 3: invalid state r110[7:5] rb_vco_sel r 0 reads back the actual vco that the calibration has selected. 0: invalid 1: vco1 ... 7: vco7 r111[7:0] rb_vco_capctrl r 183 reads back the actual capctrl capcode value the vco calibration has chosen. r112[8:0] rb_vco_daciset r 170 reads back the actual amplitude (daciset) value that the vco calibration has chosen.
58 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 8 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. 8.1 application information 8.1.1 oscin configuration oscin supports single or differential-ended clock. table 36. oscin configuration oscin type single-ended clock differential clock connection diagram input clock definitions are shown in figure 44 : figure 44. input clock definitions 8.1.2 oscin slew rate the slew rate of the oscin signal can have an impact on the spurs and phase noise of the LMX2594 if it is too low. in general, the best performance is for a high slew rate, but lower amplitude signal, such as lvds. 8.1.3 rf output buffer power control the outa_pwr and outb_pwr registers can be used to control the output power of the output buffers. the setting for optimal power may depend on the pullup component, but typically is around 50. the higher the setting, the higher the current consumption of the output buffer. 8.1.4 rf output buffer pullup the choice of output buffer components is very important and can have a profound impact on the output power. table 37 shows how to treat each pin. if using single-ended, the pullup is still needed, and user puts a 50- resistor after the capacitor. cmos sine wave differential v oscin v oscin v oscin oscin oscin* 0.1 f v t v t 50 ? 50 ? oscin oscin*
59 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated table 37. different methods for pullup on outputs pullup style diagram comments inductor potentially higher output power, but output impedance is far from 50 . consider also using with a resistive pad. resistor more consistent matching table 38. output pullup configuration component value part number inductor varies with frequency resistor 50 vishay fc0402e50r0bst1 capacitor varies with frequency atc 520l103kt16t atc 504l50r0ftncft +v cc r rfoutap c +v cc l rfoutap c
60 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 8.2 typical application figure 45. typical application schematic 8.2.1 design requirements the design of the loop filter is complex and is typically done with software. the pllatinum sim software is an excellent resource for doing this and the design is shown in the figure 46 . for those interested in the equations involved, the pll performance, simulation, and design handbook listed in the end of this document goes into great detail as to theory and design of pll loop filters.
61 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical application (continued) figure 46. pllatinum sim design screen 8.2.2 detailed design procedure the integration of phase noise over a certain bandwidth (jitter) is an performance specification that translates to signal-to-noise ratio. phase noise inside the loop bandwidth is dominated by the pll, while the phase noise outside the loop bandwidth is dominated by the vco. generally, jitter is lowest if loop bandwidth is designed to the point where the two intersect. a higher phase margin loop filter design has less peaking at the loop bandwidth and thus lower jitter. the tradeoff with this is longer lock times and spurs must be considered in design as well.
62 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated typical application (continued) 8.2.3 application curves figure 47. typical jitter
63 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 9 power supply recommendations ti recommends placement of 100 nf close to each of the power supply pins. if fractional spurs are a large concern, using a ferrite bead to each of these power supply pins can reduce spurs to a small degree. this device has integrated ldos, which improves the resistance to power supply noise. however, the pullup components on the rfouta and rfoutb pins on the outputs have a direct connection to the power supply, so extra care must be made to ensure that the voltage is clean for these pins. figure 48 is a typical application example. this device can be powered by an external dc-dc buck converter, such as the tps62150. note that although rtps, rtps1, and rtps2 are 0 in the schematic, they could be potentially replaced with a larger resistor value or inductor value for better power supply filtering. figure 48. using the tps62150 as a power supply
64 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 10 layout 10.1 layout guidelines in general, the layout guidelines are similar to most other pll devices. here are some specific guidelines. ? gnd pins may be routed on the package back to the dap. ? the oscin pins, these are internally biased and must be ac coupled. ? if not used, rampclk, rampdir, and sysrefreq can be grounded to the dap. ? for the vtune pin, try to get a loop filter capacitor as close to this as possible. this may mean separating it from the rest of the loop filter. ? for the outputs, keep the pullup component as close as possible to the pin and use the same component on each side of the differential pair. ? if a single-ended output is needed, the other side must have the same loading and pullup. however, the routing for the used side can be optimized by routing the complementary side through a via to the other side of the board. on this side, use the same pullup and make the load look equivalent to the side that is used. ? ensure dap on device is well-grounded with many vias, preferably copper filled. ? have a thermal pad that is as large as the LMX2594 exposed pad. add vias to the thermal pad to maximize thermal performance. ? use a low loss dielectric material, such as rogers 4003, for optimal output power. ? see instructions for the LMX2594evm ( LMX2594 evm instructions, 15 ghz wideband low noise pll with integrated vco ) for more details on layout.
65 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 10.2 layout example figure 49. LMX2594 pcb layout
66 LMX2594 snas696 ? march 2017 www.ti.com product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 11 device and documentation support 11.1 device support 11.1.1 third-party products disclaimer ti's publication of information regarding third-party products or services does not constitute an endorsement regarding the suitability of such products or services or a warranty, representation or endorsement of such products or services, either alone or in combination with any ti product or service. 11.1.2 development support texas instruments has several software tools to aid in the development at www.ti.com . among these tools are: ? evm software to understand how to program the LMX2594 and for programming the evm board. ? evm board instructions for seeing typical measured data with detailed measurement conditions and a complete design. ? pllatinum sim program for designing loop filters, simulating phase noise, and simulating spurs on the LMX2594. 11.2 documentation support 11.2.1 related documentation for related documentation see the following: ? an-1879 fractional n frequency synthesis ? pll performance, simulation, and design handbook ? LMX2594 evm instructions, 15 ghz wideband low noise pll with integrated vco 11.3 receiving notification of documentation updates to receive notification of documentation updates, navigate to the device product folder on ti.com. in the upper right corner, click on alert me to register and receive a weekly digest of any product information that has changed. for change details, review the revision history included in any revised document. 11.4 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. 11.5 trademarks e2e is a trademark of texas instruments. 11.6 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. 11.7 glossary slyz022 ? ti glossary . this glossary lists and explains terms, acronyms, and definitions.
67 LMX2594 www.ti.com snas696 ? march 2017 product folder links: LMX2594 submit documentation feedback copyright ? 2017, texas instruments incorporated 12 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.
package option addendum www.ti.com 30-mar-2017 addendum-page 1 packaging information orderable device status (1) package type package drawing pins package qty eco plan (2) lead/ball finish (6) msl peak temp (3) op temp (c) device marking (4/5) samples LMX2594rhar active vqfn rha 40 2500 green (rohs & no sb/br) cu nipdauag level-3-260c-168 hr -40 to 85 LMX2594 LMX2594rhat active vqfn rha 40 250 green (rohs & no sb/br) cu nipdauag level-3-260c-168 hr -40 to 85 LMX2594 (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. only one device marking contained in parentheses and separated by a "~" will appear on a device. if a line is indented then it is a continuation of the previous line and the two combined represent the entire device marking for that device. (6) lead/ball finish - orderable devices may have multiple material finish options. finish options are separated by a vertical ruled line. lead/ball finish values may wrap to two lines if the finish value exceeds the maximum column width. important information and disclaimer: the information provided on this page represents ti's knowledge and belief as of the date that it is provided. ti bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. efforts are underway to better integrate information from third parties. ti has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. ti and ti suppliers consider certain information to be proprietary, and thus cas numbers and other limited information may not be available for release.
package option addendum www.ti.com 30-mar-2017 addendum-page 2 in no event shall ti's liability arising out of such information exceed the total purchase price of the ti part(s) at issue in this document sold by ti to customer on an annual basis.
tape and reel information *all dimensions are nominal device package type package drawing pins spq reel diameter (mm) reel width w1 (mm) a0 (mm) b0 (mm) k0 (mm) p1 (mm) w (mm) pin1 quadrant LMX2594rhar vqfn rha 40 2500 330.0 16.4 6.3 6.3 1.5 12.0 16.0 q1 LMX2594rhat vqfn rha 40 250 178.0 16.4 6.3 6.3 1.5 12.0 16.0 q1 package materials information www.ti.com 31-mar-2017 pack materials-page 1
*all dimensions are nominal device package type package drawing pins spq length (mm) width (mm) height (mm) LMX2594rhar vqfn rha 40 2500 367.0 367.0 38.0 LMX2594rhat vqfn rha 40 250 210.0 185.0 35.0 package materials information www.ti.com 31-mar-2017 pack materials-page 2

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