datasheet spread spectrum clock generator ics7151a-50 idt? / ics? spread spectrum clock generator 1 ics7151a-50 rev a 102005 description the ics7151a-50 is a clock generator for emi (electromagnetic interference) reduction. spectral peaks are attenuated by modulating the system clock frequency. down or center spread pr ofiles are selectable. down spread will not exceed the maximum frequency of an unspread clock, and center spread does not change the average operating frequency of the system ics offers many other clocks for computers and computer peripherals. consult ics when you need to remove crystals and oscillators from your board. 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 ? provides a spread spectrum clock output (0.5%, 1.5% center spread; -1.0%, -3.0% down spread) ? multiplication rate of x1/2 ? advanced, low-power cmos process ? pin compatible with the fujitsu mb88151-500 block diagram 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
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 2 ics7151a-50 rev a 102005 pin assignment spread di rection and percentage select table notes: 1. pin 1 has a pull-up resistor. 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 s0 pin 3 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 1) modulation 0 no modulation 1 modulation pin number pin name pin type pin description 1 xin input crystal pin/clock input pin. 2 gnd power connect to ground. 3 s0 input select pin 0. spread modulation select. 4 s1 input select pin 1. spread modulation select. 5 ckout output clock output. 6 ens input modulation enable. internal pull-up resistor. 7 vdd power connect to +3.3 v. 8 xout output crystal connection pin.
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 3 ics7151a-50 rev a 102005 external components the ics7151a-50 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 pins 2 and 7, as close to these pins 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 ics7151a-50. 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 ics7151a-50 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
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 4 ics7151a-50 rev a 102005 absolute maximum ratings stresses above the ratings listed below can cause perman ent damage to the ics7151a-50. 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 -0.5 to 4.0 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
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 5 ics7151a-50 rev a 102005 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, output = 24 mhz 10 14 ma input frequency 16.5 33.4 mhz input high voltage v ih xin, s0, s1, ens vdd * 0.8 vdd + 0.3 v input low voltage v il xin, s0, s1, ens 0.0 vdd * 0.20 v output high voltage v oh ckout, i oh = -4 ma 2.0 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 oscillation frequency f x fundamental oscillation 16.5 33.4 mhz input frequency f in xin 16.5 33.4 mhz output frequency f out ckout, 2-frequency division 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, load capacitance 15 pf 0.5 tbd 3.0 v/ns cycle to cycle jitter t jc no load, standard deviation tbd 200 ps lock time t lk ckout 2 5 ms modulation frequency f mod ckout=tbd 33 khz
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 6 ics7151a-50 rev a 102005 input frequency (f in = 1/t in ) output slew rate thermal characteristics 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 ckin 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
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 7 ics7151a-50 rev a 102005 package outline and package dimensions (8-pin soic, 150 mil. body) package dimensions are kept current with jedec publication no. 95 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 a ccuracy and reliability, integrat ed circuit systems (ics) ass umes no responsibility for either its use or for the infringement of an y patents or other rights of third parties, which would result f rom its use. no other circuits, patents, or licenses are im plied. 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 ics. ics reserves th e right to change any circuitr y or specifications without noti ce. ics does not authorize or warrant any ics product for use in life support devices or critical medical instruments. part / order number marking shipping packaging package temperature ics7151am-50 7151am50 tubes 8-pin soic 0 to +70 c ics7151am-50t 7151am50 tape and reel 8-pin soic 0 to +70 c ics7151am-50lf 151am50l tubes 8-pin soic 0 to +70 c ics7151am-50lft 151am50l tape and reel 8-pin soic 0 to +70 c ics7151ami-50 151ami50 tubes 8-pin soic -40 to +85 c ICS7151AMI-50T 151ami50 tape and reel 8-pin soic -40 to +85 c ics7151ami-50lf 51ami50l tubes 8-pin soic -40 to +85 c ics7151ami-50lft 51ami50l tape and reel 8-pin soic -40 to +85 c index area 1 2 8 d e seating plane a1 a e - c - b .10 (.004) c c l h h x 45 *for reference only. cont rolling dimensions in mm. 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
ics7151a-50 spread spectrum clock generator sscg idt? / ics? spread spectrum clock generator 8 ics7151a-50 rev a 102005 revision history rev. originator date description of change a j. sarma 10/20/05 rev a; new device/datasheet.
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