sm843251-156 clockworks ? 10-gigabit ethernet, 156.25mhz, ultra-low ji tter lvpecl clock frequency synthesizer clockworks is a trademark of micrel, inc. rotarywave is a registered trademark of multigig, inc. femtoclocks is a registered trademark of idt, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 ( 408 ) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com general description the sm843251-156 is a 10-gigabit ethernet, 156.25mhz lvpecl clock frequency synthes izer and a member of the clockworks ? family of devices from micrel. it provides a low-noise timing solution for high-speed, high-accuracy synthesis of clock signals. it includes a patented rotarywave ? architecture that provides a very stable clock with very low noise. power supplies of either 2.5v or 3.3v are supported, with superior jitter and phase noise performance. the device synthesizes a 156.25mhz, low-noise, lvpecl output for ethernet applications. the crystal reference frequency is 25mhz. the sm843251-156 is an excellent replacement for idt femtoclocks?, with improved waveform integrity, and jitter. data sheets and support documentation can be found on micrel?s web site at: www.micrel.com . features ? generates a low-noise 156.25mhz lvpecl output ? 2.5v or 3.3v operating voltage ? typical phase jitter @156.25mhz~110fs (1.875mhz ? 20mhz) ? crystal frequency: 25mhz ? 156.25mhz output frequency ? phase noise @ 156.25mhz: ? 1khz: ? 123dbc/hz ? 10khz: ? 130dbc/hz ? 100khz: ? 135dbc/hz ? 1mhz: ? 140dbc/hz ? 10mhz: ? 161dbc/hz ? 20mhz: ? 166/dbc/hz ? industrial temperature range ? green-, rohs-, and pfos-compliant ? available in 8-pin tssop applications ? gigabit ethernet ? 10-gigabit ethernet _______________________________________________________________________________________________________ block diagram october 2010 m9999-100110-a hbwhelp@micrel.com or (408) 955-1690
micrel, inc. sm843251-156 october 2010 2 m9999-100110-a hbwhelp@micrel.com ordering information (1) part number package type operating range package marking SM843251-156KA k-8 industrial 843251-156 SM843251-156KA tr (2) k-8 industrial 843251-156 notes: 1. devices are green-, rohs-, and pfos-compliant. 2. tape and reel. pin configuration 8-pin tssop (k-8) pin description pin number pin name type level pin function 1 v dda pwr analog 2.5v or 3.3v power s upply. no filter resistor needed. 2 v ee pwr ground. 3 xtal_out o, (se) 12pf crystal crystal reference output, no load caps needed. 4 xtal_in i, (se) 12pf crystal crystal reference input, no load caps needed. 5 nc ? no connect 6 /q0 o, (dif) lvpecl differential clock output 7 q0 o, (dif) lvpecl differential clock output 8 v dd pwr 2.5v or 3.3v power supply or (408) 955-1690
micrel, inc. sm843251-156 october 2010 3 m9999-100110-a hbwhelp@micrel.com or (408) 955-1690 absolute maximum ratings (1) supply voltage (v dda , v dd ,) ........................................+4.6v input voltage (v in ) ............................... ? 0.50v to v dd + 0.5v lvpecl output current (i out ) continuous............................................................50ma surge ..................................................................100ma lead temperature (solde ring, 20sec .) ....................... 260c case temper ature ..................................................... 115c storage temperature (t s ) ......................... ? 65c to +150c operating ratings (2) supply voltage (v dd, v dda ) ........................ +2.375 to +3.465 ambient temperature (t a ) .......................... ?40c to +85c junction thermal resistance tssop ( ja )(still air) .......................................141c/w dc electrical characteristics (3) v dd = v dda = 3.3v 5%; t a = ?40c to +85c, unless noted. symbol parameter condition min. typ. max. units v dd core supply voltage 3.135 3.30 3.465 v v dda analog supply voltage 3.135 3.30 3.465 v i dda analog supply current included in i ee 50 60 ma i ee total supply current no load 88 110 ma v dd = v dda = 2.5v 5%; t a = ?40c to +85c, unless noted. symbol parameter condition min. typ. max. units v dd core supply voltage 2.375 2.50 2.625 v v dda analog supply voltage 2.375 2.50 2.625 v i dda analog supply current included in i ee 50 60 ma i ee total supply current no load 80 100 ma lvpecl dc electrical characteristics (3, 4) v dd = v dda = 2.5v 5% or 3.3v 5%, t a = ?40c to +85c, unless noted. symbol parameter condition min. typ. max. units v oh output high voltage 50? to v dd ? 2v v dd ? 1.145 v dd ? 0.97 v dd ? 0.845 v v ol output low voltage 50? to v dd ? 2v v dd ? 1.945 v dd ? 1.77 v dd ? 1.645 v v swing peak-to-peak output voltage swing 0.6 0.8 1.0 v notes: 1. permanent device damage may occur if absolute maximum ratings are exceeded. this is a stress rating only and functional oper ation is not implied at conditions other than those detailed in the operational sections of this data shee t. exposure to absolute maximum rating con ditions for extended periods may affect device reliability. 2. the data sheet limits are not guaranteed if t he device is operated beyond the operating ratings. 3. the circuit is designed to meet the dc specifications shown in the above table after thermal equilibrium has been establishe d with a transverse airflow greater than 500 lfpm. 4. see figure 4 for load test circuit example.
micrel, inc. sm843251-156 october 2010 4 m9999-100110-a hbwhelp@micrel.com ac electrical characteristics (5) v dd = v dda = 2.5v 5% or 3.3v 5% , t a = ?40c to +85c, unless noted. symbol parameter condition min. typ. max. units f out output frequency 25mhz crystal 156.25 mhz t jitter rms phase jitter (output = 156.25 mhz) integration range: 1.875m hz to 20mhz 110 fs t r / t f output rise/fall time 20% to 80% 80 175 350 ps o dc output duty cycle 48 50 52 % note: 5. the circuit is designed to meet the ac specifications shown in the above table( s) after thermal equilibrium has been establi shed with a transverse airflow greater than 500 lfpm. crystal characteristics parameter condition min. typ. max. units mode of oscillation 12pf load f undamental, parallel resonant frequency 25 mhz equivalent series resistance (esr) 50 ? shunt capacitor, c0 3 7 pf correlation drive level 100 300 uw or (408) 955-1690
micrel, inc. sm843251-156 october 2010 5 m9999-100110-a hbwhelp@micrel.com figure 1. duty cycle timing figure 2. all outputs rise/fall time figure 3. rms phase noise/jitter or (408) 955-1690
micrel, inc. sm843251-156 october 2010 6 m9999-100110-a hbwhelp@micrel.com figure 4. lvpecl output load and test circuit figure 5. crystal input interface or (408) 955-1690
micrel, inc. sm843251-156 october 2010 7 m9999-100110-a hbwhelp@micrel.com package information 8-pin tssop (k-8) micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944-0800 fax +1 (408) 474-1000 web http://www.micrel.com micrel makes no representations or warranties with respect to t he accuracy or completeness of the information furnished in this data sheet. this information is not intended as a warranty and micrel does not assume responsibility for it s use. micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. no license, whether expre ss, implied, arising by estoppel or other wise, to any intellectual property rights is granted by this document. except as provided in micrel?s terms and conditions of sale for such products, mi crel assumes no liability whatsoever, and micrel disclaims any express or implied warranty relating to the sale and/or use of micrel products including l iability or warranties relating to fitness for a particular purpose, merchantability, or infringement of an y patent, copyright or other intellectual p roperty right micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended for surgical impla into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. can nt ? 2010 micrel, incorporated. or (408) 955-1690
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