ltc6905-xxx series 1 6905xf , ltc and lt are registered trademarks of linear technology corporation. no external components to set frequency frequency error 0.5% typical fast start-up time: 100 s typical 20ppm/ c temperature stability output enable provided includes divide by 1, 2 or 4 rise time: 0.5ns, c l = 5pf timing jitter: <0.8% typical 50% 2.5% duty cycle i s = 8ma typical (f osc = 100mhz, c l = 5pf) cmos output drives 600 ? load single supply 2.7v to 5.5v low profile (1mm) thinsot tm package fixed frequency sot-23 oscillator data clocks for high reliability applications high vibration, high acceleration environments replacement for fixed crystal and ceramic oscillators the ltc 6905-xxx series of parts are precision, fixed frequency, silicon oscillators designed to minimize board space while maximizing accuracy and ease of use. programmed at the factory to a fixed frequency, the ltc6905-xxx series of parts need no external trim com- ponents. an internal three-state divider allows for division of the master clock by 1, 2 or 4, providing 3 frequencies (for each device). the ltc6905-xxx series operate with a single 2.7v to 5.5v power supply and provide a rail-to-rail, 50% duty cycle, square wave output. the oe pin will disable the output when brought low and synchronously enable the output when brought high, avoiding pulse slivers. the four products of the ltc6905-xxx family are: LTC6905-133: f osc = 133mhz, 66.7mhz, 33.3mhz ltc6905-100: f osc = 100mhz, 50mhz, 25mhz ltc6905-96: f osc = 96mhz, 48mhz, 24mhz ltc6905-80: f osc = 80mhz, 40mhz, 20mhz the ltc6905-xxx series of parts are designed with a factory trim option to modify the divider ratios from 1, 2, 4 to 8, 16, 32. a second trim option allows for additional master clock frequencies. for the alternate divider ratios and unlisted frequencies, contact ltc marketing. basic connection typical distribution of frequency error, t a = 25 c descriptio u features applicatio s u typical applicatio u thinsot is a trademark of linear technology corporation. all other trademarks are the property of their respective owners. protected by u.s. patents, including 6614313, 6342817. v + 1 2 3 5 f osc = 133mhz 3v 3v 0.1 f 6905x ta01 4 gnd LTC6905-133 oe out div open 2 1 4 % frequency error ? 0 units 10 20 30 40 v s = 3v 0.5 0.0 0.5 6905x ta02 1
ltc6905-xxx series 2 6905xf supply voltage (v + ) to gnd ........................ 0.3v to 6v div to gnd .................................... 0.3v to (v + + 0.3v) oe to gnd ..................................... 0.3v to (v + + 0.3v) output short-circuit duration (note 6) ........... indefinite operating temperature range (note 8) ltc6905c .......................................... 40 c to 85 c ltc6905i ............................................ 40 c to 85 c ltc6905h ........................................ 40 c to 125 c specified temperature range (note 8) ltc6905c ............................................... 0 c to 70 c ltc6905i ............................................ 40 c to 85 c ltc6905h ........................................ 40 c to 125 c storage temperature range ................. 65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c order part number t jmax = 125 c, ja = 150 c/w ltc6905cs5-133 ltc6905is5-133 ltc6905hs5-133 ltc6905cs5-100 ltc6905is5-100 ltc6905hs5-100 ltc6905cs5-96 ltc6905is5-96 ltc6905hs5-96 ltc6905cs5-80 ltc6905is5-80 ltc6905hs5-80 (note 1) top view s5 package 5-lead plastic sot-23 1 2 3 v + gnd oe 5 4 out div s5 part marking* ltbpm absolute axi u rati gs w ww u package/order i for atio uu w *the temperature grade is identified by a label on the shipping container. the denotes the specifications which apply over the full specified temperature range, otherwise specifications are at t a = 25 c or as noted. oe = div = v + , v + = 2.7v to 3.6v, r l = 15k, c l = 5pf, unless otherwise noted. all voltages are with respect to gnd. symbol parameter conditions min typ max units ? f frequency accuracy (notes 2, 7) ltc6905c-xxx t a = 25 c, v + = 3v 0.5 1.0 % 0 c < t a < 70 c 1.5 % ltc6905i-xxx 25 c < t a < 85 c 1.8 % ?0 c < t a < 85 c 2.9 % ltc6905h-xxx 25 c < t a < 125 c 2.3 % ?0 c < t a < 125 c 2.9 % v + = 5v 1.5 % ? f/ ? t freq drift over temp (note 2) 20 ppm/ c ? f/ ? v freq drift over supply (notes 2, 7) v + = 2.7v to 3.6v 0.5 %/v timing jitter (note 3) 0.8 % long-term stability of output frequency 300 ppm/ khr duty cycle 47.5 50 52.5 % v + operating supply range 2.7 5.5 v electrical characteristics ltbpk ltbpj ltbph
ltc6905-xxx series 3 6905xf the denotes the specifications which apply over the full specified temperature range, otherwise specifications are at t a = 25 c or as noted. oe = div = v + , v + = 2.7v to 3.6v, r l = 15k, c l = 5pf, unless otherwise noted. all voltages are with respect to gnd. electrical characteristics symbol parameter conditions min typ max units i s power supply current div = v + ( 1), v + = 3.6v LTC6905-133 10 15 ma ltc6905-100 812 ma ltc6905-96 812 ma ltc6905-80 711 ma div = 0 ( 4), v + = 3.6v LTC6905-133 58 ma ltc6905-100 47 ma ltc6905-96 47 ma ltc6905-80 3.5 6 ma v ih high level div or oe pins input voltage v + ?0.15 v v il low level div or oe pins input voltage 0.2 v i div div input current (note 4) div = v + v + = 5.5v 15 40 a div = 0v v + = 5.5v ?0 11 a i oe oe input current (note 4) oe = v + v + = 5.5v 15 a oe = 0v v + = 5.5v 11 a v oh high level output voltage (note 4) v + = 5.5v i oh = 1ma 5.25 5.45 v i oh = 4ma 5.20 5.30 v v + = 2.7v i oh = 1ma 2.5 2.6 v i oh = 4ma 2.3 2.5 v v ol low level output voltage (note 4) v + = 5.5v i ol = 1ma 0.05 0.25 v i ol = 4ma 0.2 0.3 v v + = 2.7v i ol = 1ma 0.1 0.3 v i ol = 4ma 0.4 0.5 v t r , t f out rise/fall time (note 5) 0.5 ns note 1: absolute maximum ratings are those values beyond which the life of the device may be impaired. note 2: frequency accuracy is tested with div = v + ( 1). other divide ratios are guaranteed by design. note 3: jitter is the ratio of the peak-to-peak distribution of the period to the mean of the period. this specification is based on characterization and is not 100% tested. note 4: to conform with the logic ic standard convention, current out of a pin is arbitrarily given as a negative value. note 5: output rise and fall times are measured between the 10% and 90% power supply levels. note 6: a heat sink may be required to keep the junction temperature below the absolute maximum when the output is shorted indefinitely. note 7: the ltc6905 is optimized for the performance with a 3v power supply voltage. refer to typical performance characteristics curves in this data sheet for additional information regarding the ltc6905 voltage coefficient, especially between 4.5v and 5.5v. please consult ltc marketing for parts optimized for 5v operation. note 8: the ltc6905c-xxx is guaranteed functional over the operating temperature range and is guaranteed to meet specified performance from 0 c to 70 c. the ltc6905c-xxx is designed, characterized and expected to meet specified performance from ?0 c to 85 c but is not tested or qa sampled at these temperatures. the ltc6905i-xxx is guaranteed to meet specified performance from ?0 c to 85 c.
ltc6905-xxx series 4 6905xf ltc6905-80 output operating at 20mhz, v s = 3v LTC6905-133 output operating at 133mhz, v s = 3v r out vs v + jitter vs frequency supply voltage (v) 2.5 0 output resistance ( ? ) 5 15 20 25 4.5 45 6905x g04 10 3.5 3 5 4 5.5 30 35 40 frequency (mhz) 0 0 jitter (%) 0.20 0.60 4 2 1 0.80 1.00 40 80 100 180 6905x g05 0.40 20 60 120 140 160 1.20 typical perfor a ce characteristics uw frequency vs temperature temperature ( c) ?0 ?.0 percentage error (%) ?.8 ?.4 ?.2 0 1.0 0.4 0 40 60 6905x g08 ?.6 0.6 0.8 0.2 ?0 20 80 100 120 supply current vs frequency frequency (mhz) 0 supply current (ma) 10 12 14 200 6905x g01 8 4 4 1 1 6 0 2 50 100 150 4 18 16 5.5v 2.7v 2 2 frequency error vs supply voltage supply voltage (v) 2.5 ?.50 frequency error (%) o 0.50 1.00 1.50 2.50 3 3.5 4 4.5 6905x g09 5 5.5 2.00 LTC6905-133 ltc6905-100 ltc6905-96 ltc6905-80 0.75v/div 10ns/div 6905x g06 0.75v/div 2.5ns/div 6905x g07
ltc6905-xxx series 5 6905xf block diagra w + + + 1 3 gain = 1 v + v bias i res i res r set gnd master oscillator programmable divider (n = 1, 2 or 4) v res = 1v 5% (v + ?v set ) three-state input detect gnd v + 15 a 6905x bd 15 a out oe f mo divider select 5 div 4 2 f osc = f mo n uu u pi fu ctio s v + (pin 1): voltage supply (2.7v v + 5.5v). this supply must be kept free from noise and ripple. it should be bypassed directly to the gnd (pin 2) with a 0.1 f capacitor or higher. gnd (pin 2): ground. should be tied to a ground plane for best performance. oe (pin 3): output enable. pull to v+ or leave floating to enable the output driver (pin 5). pull low to disable the output. the output is disabled asynchronously. pulling oe pin low will immediately disable the output. pulling the oe pin high will bring the output high on the next low to high transition of the clock. this eliminates pulse slivers. div (pin 4): divider-setting input. this three-state input selects among three divider settings. pin 4 should be tied to v + for the 1 setting, the highest frequency range. float- ing pin 4 divides the master oscillator by 2. pin 4 should be tied to gnd for the 4 setting, the lowest frequency range. to detect a floating div pin, the ltc6905 attempts to pull the pin toward midsupply. this is realized with two internal current sources, one tied to v + and pin 4 and the other one tied to ground and pin 4. therefore, driving the div pin high requires sourcing approximately 15 a. likewise, driving div low requires sinking 15 a. when pin 4 is floated, it should be bypassed by a 1nf capacitor to ground or it should be surrounded by a ground shield to prevent excessive cou- pling from other pcb traces. out (pin 5): oscillator output. this pin can drive 5k ? and/or 5pf loads. for heavier loads, refer to the applica- tions information section. table 1. ltc6905-xxx frequency settings div setting LTC6905-133 ltc6905-100 ltc6905-96 ltc6905-80 v+ 133.33mhz 100mhz 96mhz 80mhz open 66.66mhz 50mhz 48mhz 40mhz gnd 33.33mhz 25mhz 24mhz 20mhz
ltc6905-xxx series 6 6905xf applicatio s i for atio wu uu start-up time the start-up and settling time to within 1% of the final frequency is typically 100 s. maximum output load the ltc6905 output (pin 5) can drive a capacitive load (c load ) of 5pf or more. performance driving a c load greater than 5pf depends on the oscillator? frequency (f osc ) and output resistance (r out ). the output rise time or fall time due to r out and c load is equal to 2.2 r out c load (from 10% to 90% of the rise or fall transition). if the total output rise time plus fall time is arbitrarily specified to be equal to or less than 20% of the oscillator? period (1/ f osc ), then the maximum output c load in picofarads (pf) should be equal to or less than [45454/(r out f osc )] (r out in ohms and f osc in mhz). example: an ltc6905-100 is operating with a 3v power supply and is set for a f osc = 50mhz. r out with v + = 3v is 27 ? (using the r out vs v + graph in the typical performance characteristics). the maximum output c load should be equal to or less than [45454/(27 ?50)] = 33.6pf. the lowest resistive load pin 5 can drive can be calculated using the minimum high level output voltage in the elec- trical characteristics. with a v + equal to 5.5v and 4ma output current, the minimum high level output voltage is 5.2v and the lowest resistive load pin 5 can drive is 1.30k (5.2v/4ma). with a v + equal to 2.7v and 4ma output current, the minimum high level output voltage is 2.4v and the lowest resistive load pin 5 can drive is 600 ? (2.4v/4ma). frequency accuracy and power supply noise the frequency accuracy of the ltc6905 may be affected when its power supply generates noise with frequency contents equal to f mo /64 or its multiples. f mo is the highest frequency for an ltc6905-xxx which is with div = v + ( 1). this is also the frequency indicated in the part number (i.e., ltc6905-100, f mo = 100mhz). f mo /64 is the master oscillator control loop frequency. for ex- ample, if the ltc6905-80 with a master oscillator fre- quency of 80mhz is powered by a switching regulator, then the oscillator frequency may show an additional error if the switching frequency is 1.4mhz (80mhz/64). the magnitude of this effect is heavily dependent on supply bypass and routing. jitter and power supply noise if the ltc6905 is powered by a supply that has frequency content equal to the output frequency then the output jitter may increase. in addition, power supply ripple in excess of 20mv at any frequency may increase jitter. higher divide ratios will result in lower percentage jitter. for example, jitter percentage of the ltc6905-80 operat- ing at 20mhz is lower than for the same part operating at 80mhz. please consult the jitter vs frequency graph showing jitter at various divider ratios. ltc6905 suggested critical component layout in order to provide the specified performance, it is re- quired that the supply bypass capacitor be placed as close as possible to the ltc6905. the following additional rules should be followed for best performance: 1) the bypass capacitor must be placed as close as possible to the ltc6905, and no vias should be placed between the capacitor and the ltc6905. the bypass capacitor must be on the same side of the circuit board as the ltc6905. 2) if a ground plane is used, the connection of the ltc6905 to the ground plane should be as close as possible to the ltc6905 gnd pin and should be composed of multiple, high current capacity vias. figure 2. ltc6905 suggested critical component layout ltc6905 6905x f02 c
ltc6905-xxx series 7 6905xf information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. package descriptio u s5 package 5-lead plastic tsot-23 (reference ltc dwg # 05-08-1635) 1.50 ?1.75 (note 4) 2.80 bsc 0.30 ?0.45 typ 5 plcs (note 3) datum ? 0.09 ?0.20 (note 3) s5 tsot-23 0302 pin one 2.90 bsc (note 4) 0.95 bsc 1.90 bsc 0.80 ?0.90 1.00 max 0.01 ?0.10 0.20 bsc 0.30 ?0.50 ref note: 1. dimensions are in millimeters 2. drawing not to scale 3. dimensions are inclusive of plating 4. dimensions are exclusive of mold flash and metal burr 5. mold flash shall not exceed 0.254mm 6. jedec package reference is mo-193 3.85 max 0.62 max 0.95 ref recommended solder pad layout per ipc calculator 1.4 min 2.62 ref 1.22 ref
ltc6905-xxx series 8 6905xf linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2005 lt/tp 0205 1k ? printed in usa related parts part number description comments ltc1799 1khz to 33mhz thinsot oscillator single output, high frequency operation ltc6900 1khz to 20mhz thinsot oscillator single output lower power ltc6902 multiphase oscillator with spread spectrum modulation 2-, 3- or 4-phase outputs ltc6903/ltc6904 1khz to 68mhz serial port programmable oscillator 3-wire or i 2 c tm programmable ltc6905 17mhz to 170mhz resistor set thinsot oscillator single resistor sets frequency ltc6906 micropower, 10khz to 1mhz resistor set thinsot oscillator ultralow power, resistor sets frequency typical applicatio s u driving a 50 ? cable with the ltc6905 v + 1 2 3 5 950 ? 50 ? 50 ? cable 3v 3v 0.1 f 6905x ta02 4 gnd ltc6905-xxx oe out div v out 20 driving the div pin without three-state buffers v + 1 2 a b 3 5 3v 3v 3v 0.1 f 6905x ta04 4 10k 10k gnd ltc6905-xxx oe out div a 0 0 1 1 b 0 1 0 1 div 1 2 2 4
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