? 2014 exar corporation XR81101 universal clock - high frequency lvcmos clock synthesizer exar.comXR81101 rev 1a 1 / 8 general description the XR81101-aa02 is a clock synthesizer operating a t a 3.3v/2.5v sup- ply with integer divider, using a 25mhz parallel re sonant crystal reference input provides a 125mhz lvcmos output. the device i s optimized for use with a 25mhz crystal (or system clock) and gene rates a 125mhz out- put clock for ge applications. the lvcmos output ha s very low phase noise jitter of sub 150fs, while consuming extremely low power. the application diagram below shows a typical synth esizer configuration with any standard crystal oscillating in fundamental mode. internal load capacitors are optionally available to minimize/elim inate external crystal loads. a system clock can also be used to overdrive the oscillator for a synchronous timing system. the typical phase noise plot below shows the jitter integrated over the 1.875mhz to 20mhz range that is widely used in wan systems. these clock devices show a very good high frequency noise floor below -150db. the XR81101 is a family of universal clock synthesize r devices in tssop-8 packages. the devices generate any frequenc y in the range of 10mhz to 200mhz by utilizing a highly flexible delta sigma modulator and a wide ranging vco. these devices can be used with standard crystals or external system clock to support a wide variety of a pplications. this family of products has an extremely low power pll block wit h core power con- sumption 40% less than the equivalent devices from competition. by sec- ond sourcing several of the existing sockets, these devices provides a very compelling power efficiency value benefit acros s all market seg- ments. other clock multiplier and/or driver configurations are possible in this clock family and can be requested from the factory features ? XR81101-aa02: factory configured ? one lvcmos output ? crystal oscillator interface which can also be overdriven using a single-ended reference clock ? output frequency: 125mhz ? crystal/input frequency: 25mhz, parallel resonant crystal ? rms phase jitter @ 125mhz, 1.875mhz - 20mhz: < 150fs ? full 3.3v or 2.5v operating supply ? -40c to 85c ambient operating temperature ? lead-free (rohs 6) package applications ? gigabit ethernet ? low-jitter clock generation ? synchronized clock systems ordering information C page 8 typical application XR81101 phase noise (dbc/hz) 100hz 1khz 10khz 100 khz 1mhz 10mhz -120db -160db -140db -100db -80db -60db -180db -40db rms jitter = 123.6fs int range 1.875mhz to 20mhz v cc 2.5v or 3.3v q 125mhz v e e oe xtal_in xtal_out 25mhz enable XR81101 r aa02
? 2014 exar corporation XR81101 2 / 8 exar.com/XR81101 rev 1a absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any maximum rating condition for extende d periods may affect device reliability and lifetime. supply voltage..................................... .....................+4.2v input voltage...................................... -0.5v to vcc + 0.5v output voltage...................................-0 .5v to vcc + 0.5v reference frequency/input crystal.........10mhz to 60mh z storage temperature................................ -55c to +125c lead temperature (soldering, 10 sec)............... ......300c esd rating (hbm - human body model)................. ...2kv operating conditions operating temperature range.....................-40 c to +85c
? 2014 exar corporation XR81101 3 / 8 exar.com/XR81101 rev 1a electrical characteristics unless otherwise noted: t a = -40c to +85c, v cc = 3.3v5% or 2.5v5%, v ee = 0v symbol parameter conditions * min typ max units 3.3v power supply dc characteristics v cc power supply voltage ? 3.135 3.3 3.465 v i ee power supply current 125mhz with output unloaded. 24 m a 2.5v power supply dc characteristics v cc power supply voltage ? 2.375 2.5 2.625 v i ee power supply current 125mhz with the output unloaded . 21 ma lvcmos/lvttl dc characteristics * limits applying over the full operating temperatu re range are denoted by a ?. v ih input high voltage v cc = 3.465v ? 2.42 v cc + 0.3 v v cc = 2.625v ? 1.83 v cc + 0.3 v v il input low voltage v cc = 3.465v ? -0.3 1.03 v v cc = 2.625v ? -0.3 0.785 v i ih input high current (oe, fsel[1:0]) v in = v cc = 3.465v or 2.625v ? 15 a i il input low current (oe, fsel[1:0]) v in = 0v, v cc = 3.465v or 2.625v ? -10 a lvcmos dc characteristics v oh output high voltage output unloaded ? 0.8 x v cc v v ol output low voltage output unloaded ? 0.1 x v cc v crystal characteristics x mode mode of oscillations fundamental x f frequency 25 mhz esr equivalent series resistance 50 c s shunt capacitance 7 pf ac characteristics f out output frequency 125 mhz t jit ( i ) rms phase jitter 125mhz (int. range 1.875mhz-20mhz) 0.15 ps t jit (cc) cycle-to-cycle jitter using 25mhz, 18pf resonant crystal ? 10 ps t r /t f output rise/fall time 20% to 80% ? 100 550 ps odc output duty cycle ? 48 52 % symbol parameter conditions * min typ max units
? 2014 exar corporation XR81101 4 / 8 exar.com/XR81101 rev 1a pin configuration pin assignments pin no. pin name type description 1 v cc supply power supply pin. 2 oe input (900k : pull-up) output enable pin - lvcmos/lvttl active high input. outputs are enabled when oe = high. outputs are disabled when oe = low. 3 xtal_out output crystal oscillator output. 4 xtal_in input crystal oscillator input. 5 nc no connect unused, do not connect. 6 v ee supply negative supply pin. 7 q output lvcmos output. 8 v cc supply power supply pin. 13 4 5 6 7 8 2 xtal_out xtal_in q v cc v cc v ee oe nc
? 2014 exar corporation XR81101 5 / 8 exar.com/XR81101 rev 1a functional block diagram typical performance characteristics figure 1 shows a typical phase noise performance pl ots for a 125mhz clock output. the data was taken u sing the industry standard agilent e5052b phase noise instrument. the integration range is 1.875mhz to 20mhz. figure 1: 125mhz operation, typical phase noise at 3.3v osc pdf & lpf vco divide by n divide by m q xtal_in xtal_out m/n = 5 oe
? 2014 exar corporation XR81101 6 / 8 exar.com/XR81101 rev 1a application information termination for lvcmos outputs the termination schemes shown in figure 2 and figure 3 are typical for lvcmos outputs. a split supply appro ach can be used utilizing the scopes internal 50 : impedance, as shown in figure 4. figure 2: XR81101 3.3v lvcmos output termination figure 3: XR81101 2.5v lvcmos output termination figure 4: XR81101 split supply lvcmos output termin ation output signal timing definitions the following diagrams clarify the common definitio ns of the ac timing measurements. figure 5: cycle-to-cycle jitter figure 6: output rise/fall time 100 : 100 : z = 50 : high impedance scope probe lvcmos output 3.3v 5% 3.3v 5% 100 : : z = 50 : high impedance scope probe lvcmos output 2.5v 5% 2.5v 5% : z = 50 : lvcmos output +vcc/2 5% scope -vcc/2 5% vcc vss 80% 20% 80% 20% t r t f lvcmos output v cc /2 t pw t period lvcmos output odc = t pw t period 100%
? 2014 exar corporation XR81101 7 / 8 exar.com/XR81101 rev 1a mechanical dimensions 8-pin tssop note: the side, top and landing pattern drawings ar e general to tssop packaging but the table is speci fic to the 8pin tssop. t t t t
? 2014 exar corporation XR81101 8 / 8 exar.com/XR81101 rev 1a for further assistance: email: commtechsupport@exar.com exar technical documentation: http://www.exar.com/techdoc/ exar corporation headquarters and sales offices 48720 kato road tel: +1 (5 10) 668-7000 fremont, ca 95438 - usa fax: +1 (510) 66 8-7001 notice exar corporation reserves the right to make changes to the products contained in this publication in o rder to improve design, performance or reliability. exar corporation assumes no responsibility for the use of any circuit s described herein, conveys no license under any pat ent or other right, and makes no representation tha t the circuits are free of patent infringement. charts and schedules contai ned herein are only for illustration purposes and m ay vary depending upon a users specific application. while the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracie s. exar corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reaso nably be expected to cause failure of the life support system or to signi ficantly affect its safety or effectiveness. products are not authorized for use in such applications un less exar corporation receives, in writing, assurances to its satisfactio n that: (a) the risk of injury or damage has been mi nimized; (b) the user assumes all such risks; (c) p otential liability of exar cor- poration is adequately protected under the circumsta nces. reproduction, in part or whole, without the prior w ritten consent of exar corporation is prohibited. ordering information revision history part number package green operating temperature range shipping packaging marking XR81101-aa02-f 8-pin tssop yes -40c to +85c tube t01 XR81101-aa02tr-f 8-pin tssop yes -40c to +85c tape & reel t01 XR81101evb eval board n/a n/a n/a n/a revision date description 1a april 2014 initial release. [ecn1416-07 l 04/18/2014]
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