datasheet spread spectrum clock generator ics7151 idt? / ics? spread spectrum clock generator 1 ics7151 rev g 022107 description the ics7151-10, -20, -40, and -50 are clock generators for emi (electro magnetic interference) reduction (see below for frequency ranges and multiplier ratios). spectral peaks can be attenuat ed by slightly modu lating the oscillation frequency. both down and center spread profiles are selectable. down spread maintains an average frequency less than an unspread cloc k, and will not exceed the maximum frequency of an unspread clock. features ? operating voltage of 3.3 v 0.3 v ? packaged in 8-pin soic ? available in pb (lead) free package ? input frequency range of 16.5 to 33.4 mhz ? output frequency ranges of 8.3 to 16.7 mhz, 16.5 to 33.4 mhz, 33.3 to 66.7 mhz, 66.6 to 133.4 mhz ? provides a spread spectrum clock output (0.5%, 1.5% center spread; -1.0%, -3.0% down spread) ? multiplication rates of x1/2, x1, x2, and x4 ? advanced, low-power cmos process block diagram product lineup product input frequency range multiplier ratio output frequency range ics7151m-10, ics7151mi-10 16.5 mhz to 33.4 mhz x1 16.5 mhz to 33.4 mhz ics7151m-20, ics7151mi-20 16.5 mhz to 33.4 mhz x2 33.3 mhz to 66.7 mhz ics7151m-40, ics7151mi-40 16.5 mhz to 33.4 mhz x4 66.6 mhz to 133.4 mhz ics7151M-50, ics7151mi-50 16.5 mhz to 33.4 mhz x1/2 8.3 mhz to 16.7 mhz pll clock synthesis and spread spectrum circuitry s1:0 ens ckout 2 gnd vdd clock buffer/ crystal ocsillator xin xout external caps required with crystal for accurate tuning of the clock
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 2 ics7151 rev g 022107 pin assignment spread di rection and percentage select table notes: 1. the modulation rate varies with input frequency. 2. spread will default to on when ens pin is left open. pin descriptions xout gnd s0 vdd s1 ckout ens xin 1 2 3 4 8 7 6 5 8 pin (150 mil) soic s1 pin 4 (note1) s0 pin 3 (note1) spread direction spread percentage (%) 0 0 center 1.5 0 1 center 0.5 10 down -1.0 1 1 down -3.0 ens (note 2) spread spectrum 0 off 1 on pin number pin name pin type pin description 1 xin input resonator connection pin/clock input pin. 2 gnd power connect to ground. 3 s0 input select pin 0. modulation rate setting pin. 4 s1 input select pin 1. modulation rate setting pin. 5 ckout output modulated clock output pin. 6 ens input modulation enable setting pin. internal pull-up resistor. 7 vdd power connect to +3.3 v. 8 xout output resonator connection pin.
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 3 ics7151 rev g 022107 external components the ics7151 requires a minimum number of external components for proper operation. decoupling capacitor a decoupling capacitor of 0.01f must be connected between gnd and vdd on pin 7, as close to this pin as possible. for optimum device performance, the decoupling capacitor should be mounted on the component side of the pcb. avoid the use of vias in the decoupling circuit. series termination resistor series termination should be used on the clock output. to series terminate a 50 ? trace (a commonly used trace impedance) place a 27 ? resistor in series with the clock line, as close to the clock output pin as possible. the nominal impedance of the clock output is 25 ? . pcb layout recommendations for optimum device performance and lowest output phase noise, the following guidelin es should be observed. 1) the 0.01f decoupling capacitor should be mounted on the component side of the board as close to the vdd pin as possible. no vias should be used between the decoupling capacitor and vdd pin. the pcb trace to vdd pin should be kept as short as possible, as should the pcb trace to the ground via. 2) to minimize emi, the 27 ? series termination resistor (if needed) should be placed close to the clock output. 3) an optimum layout is one with all components on the same side of the board, minimizing vias through other signal layers. other signal traces should be routed away from the ics7151. this includes signal traces just underneath the device, or on layers adjacent to the ground plane layer used by the device. crystal information the crystal used should be a fundamental mode (do not use third overtone), parallel resonant. crystal capacitors should be connected from pins x1 to ground and x2 to ground to optimize the initial accuracy. the value of these capacitors is given by the following equation: crystal caps (pf) = (c l - 6) x 2 in the equation, c l is the crystal load capacitance. so, for a crystal with a 16 pf load capacitance, two 20 pf [(16-6) x 2] capacitors should be used. spread spectrum profile the ics7151 low emi clock generator uses a triangular frequency modulation profile for optimal down stream tracking of zero delay buffers and other pll devices. the frequency modulation amplitude is constant with variations of the input frequency. time frequency modulation rate
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 4 ics7151 rev g 022107 absolute maximum ratings stresses above the ratings listed below can cause perm anent damage to the ics7151. these ratings, which are standard values for ics commercially rated parts, are stress ratings only. functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for exte nded periods can affect product reliability. electrical parameters are guaranteed only over the recommended operating temperature range. overshoot/undershoot recommended operation conditions item rating supply voltage, vdd 7 v all inputs and outputs (referenced to gnd) -0.5 v to vdd+0.5 v ambient operating temperature -40 to +85 c storage temperature -55 to +125 c junction temperature -40 to +125 c soldering temperature 260 c overshoot (v iover ) vdd + 1.0 v (t over < 50 ns) undershoot (v iunder ) gnd - 1.0 v (t under < 50 ns) parameter min. typ. max. units ambient operating temperature -40 +85 c power supply voltage (measured in respect to gnd) +3.0 3.3 3.6 v input pin v iover < v dd + 1.0 v v iunder < gnd - 1.0 v t over < 50 ns t under < 50 ns v dd gnd
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 5 ics7151 rev g 022107 dc electrical characteristics unless stated otherwise, vdd = 3.3 v 0.3 v , ambient temperature -40 to +85 c ac electrical characteristics unless stated otherwise, vdd = 3.3 v 0.3 v , ambient temperature -40 to +85 c parameter symbol conditions min. typ. max. units operating voltage vdd 3.0 3.3 3.6 v supply current idd no load, at 3.3 v 10 20 ma input high voltage v ih xin, s0, s1, ens vddx0.8 vdd + 0.3 v input low voltage v il xin, s0, s1, ens 0.0 vddx0.20 v output high voltage v oh ckout, i oh = -4 ma vdd-0.5 v output low voltage v ol ckout, i ol = 4 ma 0.4 v input capacitance c in xin, s0, s1, ens 16 pf load capacitance c l ckout, 8.3 to 66.7 mhz 15 pf ckout, 66.7 to 100 mhz 10 pf ckout, 100 to 133.4 mhz 7pf input pull-up resistor r pu ens 100 240 400 k ? parameter symbol conditions min. typ. max. units input crystal frequency 16.5 33.4 mhz input clock frequency f in 16.5 33.4 mhz output frequency f out ckout, multiply by 1 (ics7151-10) 16.5 33.4 mhz ckout, multiply by 2 (ics7151-20) 33.3 66.7 mhz ckout, multiply by 4 (ics7151-40) 66.6 133.4 mhz ckout, 2-frequency division (ics7151-50) 8.3 16.7 mhz input clock duty cycle xin, 16.5 to 33.4 mhz 40 50 60 % output clock duty cycle t dcc ckout, 1.5 v 40 60 % output slew rate ckout, 0.4 to 2.4 v, cl = 15 pf 0.5 3.0 v/ns
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 6 ics7151 rev g 022107 input frequency (f in = 1/t in ) output slew rate thermal characteristics 8 soic cycle to cycle jitter t jc no load, spread off (ics7151-10, -20) 100 ps no load, spread off (ics7151-40) 150 ps no load, spread off (ics7151-50) 200 ps power-up time pll lock-time from power-up to 1% of final value 25ms modulation frequency f mod ckout 33 khz parameter symbol conditions min. typ. max. units thermal resistance junction to ambient ja still air 150 c/w ja 1 m/s air flow 140 c/w ja 3 m/s air flow 120 c/w thermal resistance junction to case jc 40 c/w parameter symbol conditions min. typ. max. units xin t in 0.8 v dd ckout sr = (2.4 - 0.4) /t r , sr = (2.4 - 0.4) /t f t r 2.4 v t f 0.4 v
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 7 ics7151 rev g 022107 package outline and package dimensions (8-pin soic, 150 mil. body) package dimensions are kept current with jedec publication no. 95 index area 1 2 8 d e seating plane a1 a e - c - b .10 (.004) c c l h h x 45 millimeters inches symbol min max min max a 1.35 1.75 .0532 .0688 a1 0.10 0.25 .0040 .0098 b 0.330.51.013.020 c 0.19 0.25 .0075 .0098 d 4.80 5.00 .1890 .1968 e 3.80 4.00 .1497 .1574 e 1.27 basic 0.050 basic h 5.80 6.20 .2284 .2440 h 0.250.50.010.020 l 0.401.27.016.050 0 8 0 8
ics7151 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 8 ics7151 rev g 022107 ordering information parts that are ordered with a ?lf? suffix to the part nu mber are the pb-free configur ation and are rohs compliant. while the information presented herein has been checked for both accuracy and reliability, integrated device technology (idt) a ssumes no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would resul t from its use. no other circuits, patents, or licenses are implied. this product is intended for use in normal commercial applications. any other applications such as those requiring extended temperature range, high reliab ility, or other extraordinary environmental requirements are not recommended without additional processing by idt. idt reserves the right to change any circuitry or specifications without noti ce. idt does not authorize or warrant any idt product for use in life support devices or critical medical instruments. part / order number marking shipping packaging package temperature 7151m-10 7151m-10 tubes 8-pin soic 0 to +70 c 7151m-10t 7151m-10 tape and reel 8-pin soic 0 to +70 c 7151m-10lf 51m-10lf tubes 8-pin soic 0 to +70 c 7151m-10lft 51m-10lf tape and reel 8-pin soic 0 to +70 c 7151m-20 7151m-20 tubes 8-pin soic 0 to +70 c 7151m-20t 7151m-20 tape and reel 8-pin soic 0 to +70 c 7151m-20lf 51m-20lf tubes 8-pin soic 0 to +70 c 7151m-20lft 51m-20lf tape and reel 8-pin soic 0 to +70 c 7151m-40 7151m-40 tubes 8-pin soic 0 to +70 c 7151m-40t 7151m-40 tape and reel 8-pin soic 0 to +70 c 7151m-40lf 51m-40lf tubes 8-pin soic 0 to +70 c 7151m-40lft 51m-40lf tape and reel 8-pin soic 0 to +70 c 7151M-50 7151M-50 tubes 8-pin soic 0 to +70 c 7151M-50t 7151M-50 tape and reel 8-pin soic 0 to +70 c 7151M-50lf 51m-50lf tubes 8-pin soic 0 to +70 c 7151M-50lft 51m-50lf tape and reel 8-pin soic 0 to +70 c 7151mi-10 7151mi10 tubes 8-pin soic -40 to +85 c 7151mi-10t 7151mi10 tape and reel 8-pin soic -40 to +85 c 7151mi-10lf 51mi10lf tubes 8-pin soic -40 to +85 c 7151mi-10lft 51mi10lf tape and reel 8-pin soic -40 to +85 c 7151mi-20 7151mi20 tubes 8-pin soic -40 to +85 c 7151mi-20t 7151mi20 tape and reel 8-pin soic -40 to +85 c 7151mi-20lf 51mi20lf tubes 8-pin soic -40 to +85 c 7151mi-20lft 51mi20lf tape and reel 8-pin soic -40 to +85 c 7151mi-40 7151mi40 tubes 8-pin soic -40 to +85 c 7151mi-40t 7151mi40 tape and reel 8-pin soic -40 to +85 c 7151mi-40lf 51mi40lf tubes 8-pin soic -40 to +85 c 7151mi-40lft 51mi40lf tape and reel 8-pin soic -40 to +85 c 7151mi-50 7151mi50 tubes 8-pin soic -40 to +85 c 7151mi-50t 7151mi50 tape and reel 8-pin soic -40 to +85 c 7151mi-50lf 51mi50lf tubes 8-pin soic -40 to +85 c 7151mi-50lft 51mi50lf tape and reel 8-pin soic -40 to +85 c
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