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1 of 27 gs4915 clockcleaner? data sheet 39145 - 5 june 2009 gs4915 clockcleaner? www.gennum.com key features ? reduces jitter for clocks of 148.5mhz, 148.5/1.001mhz, 74.25mhz, 74.25/1.001mhz and 27mhz ? output jitter as low as 20ps peak to peak ? automatic bypass mode for all other clock rates ? loop bandwidth adjustable as low as 2khz ? output skew control ? input selectable as differential or single-ended ? both single-ended and differential outputs ? uses the go1555 vco ? small 6mm x 6mm 40-pin qfn package ? pb-free and rohs compliant applications high definition video systems. digital video recording, playback, processing and display devices. description the gs4915 provides a low jitt er clock output when fed with an hd or sd video clock input. other input clock frequencies between 12mhz and 165mhz can be automatically passed through to the gs4915 outputs. an internal 2:1 mux allows the user to select between a differential or single-ended (lvcmos) input clock. both a single-ended lvcmos- compatible and an lvds-compatible differential output are provided. the gs4915 may operate in either auto or fixed frequency mode. in auto mode, the device will automatically clean the selected input clock if its frequency is found to be one of the supported sd or hd clock rates. in fixed mode, the user selects only one of these frequencies to be cleaned. in addition, the device allows the user to select between auto or manual bypass operation. in autobypass mode, the gs4915 will automatically bypa ss its cleaning stage and pass the input clock signal directly to the output whenever the device is unlocked, which includes the case where the input frequency is something other than the five frequencies supported. in manual bypass mode, the input signal passes through directly to the output. the gs4915 can optionally double the output frequency for 74.25mhz or 74.175mhz hd cl ocks in order to provide optimal jitter performanc e of some serializers. the gs4915 also provides the user with a 2-state skew control. the output clocks produced by the device may be advanced by ? of an output clk period in order to accommodate downstream setup and hold requirements. the gs4915 is designed to operate with the go1555 vco. the gs4915 clock cleaner complements gennum's gs4911b clock and timing gene rator for implementing a video genlock solution. wherea s the gs4911b itself cleans low-frequency jitter, the gs 4915 is designed to clean primarily the higher frequency jitter of clocks generated by the gs4911b.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 2 of 27 functional block diagram gs4915 functional block diagram 2.5v regulator phase detector charge pump divide by n skew select digital control block frequency detection diff i/p buffer s-e i/p buffer clock cleaning pll diff o/p buffer s-e o/p buffer clkin clkin clkin_se ipsel clkout_se clkout clkout skew_en bypass autobypass fctrl[1:0] double reg_vdd vco_vdd cp_vdd lf vco receiver vco cp_res lock clkout clkin bypass reset vco 0 1 0 1
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 3 of 27 revision history version ecr pcn date changes and/or modifications 5 151935 C june 2009 updated document with new template. 4 149060 C february 2008 updated figure 4-1: gs4915 typical application circuit . 3 146729 C november 2007 converted document to data sheet. updated power consumption values in table 2-1: dc electrical characteristics . 2 145306 C august 2007 defined io_vdd see note 5 in 2.2 dc electrical characteristics and added chamfer dimensions in 6.3 recommended pcb footprint . added pin descriptions for d-vdd, in_vdd and seto 1.2 pin descriptions . changed loop bandwidth to 2khz in key features . added section 3.3.3 loop filter and table 3-1: loop filter component values . changed some pin descriptions. updated power consumption values in table 2-1: dc electrical characteristics . 1 144087 43245 february 2007 corrected pin 38 (cp_vdd) connection on typical application circuit . 0 142746 C november 2006 modified table 1-1: pin descriptions . updated dc electrical characteristics and ac electrical characteristics table. modified typical application circuit . added junction - board thermal resistance parameter to section 6.4 packaging data .
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 4 of 27 contents key features ................................................................................................................... .....................................1 applications................................................................................................................... ......................................1 description.................................................................................................................... .......................................1 functional block diagram ..................................... .................................................................. .......................2 revision history ............................................................................................................... ..................................3 1. pin out..................................................................................................................... ..........................................5 1.1 pin assignment ............................................................................................................ ......................5 1.2 pin descriptions .......................................................................................................... ......................6 2. electrical characteristics .................................................................................................. ..........................9 2.1 absolute maximum ratings .................................................................................................. ........9 2.2 dc electrical characteristics ...... ....................................................................................... ...........9 2.3 ac electrical characterist ics ............................................................................................. ........ 10 3. detailed description........................................................................................................ .......................... 12 3.1 functional overview ....................................................................................................... ............. 12 3.2 clock inputs .............................................................................................................. ....................... 12 3.2.1 differential clock input................................................................................................. .. 13 3.2.2 single-ended clock input............................................................................................... 13 3.2.3 input clock selection .................................................................................................... ... 13 3.2.4 unused clock inputs ...................................................................................................... .. 13 3.3 clock cleaning pll ........................................................................................................ ............... 13 3.3.1 phase detector........................................................................................................... ......... 14 3.3.2 charge pump.............................................................................................................. ......... 14 3.3.3 loop filter .............................................................................................................. .............. 14 3.3.4 external vco ............................................................................................................. ......... 15 3.4 modes of operation ........................................................................................................ .............. 15 3.4.1 frequency modes .......................................................................................................... .... 15 3.4.2 bypass modes ............................................................................................................. ........ 17 3.5 output clock frequency and jitter ......................................................................................... 18 3.6 output skew ............................................................................................................... ..................... 20 3.7 clock outputs ............................................................................................................. .................... 21 3.7.1 differential clock output ............................................................................................... 2 1 3.7.2 single-ended clock output ........................................................................................... 21 3.8 device reset .............................................................................................................. ...................... 21 3.8.1 hardware reset........................................................................................................... ....... 21 4. typical application circuit ......... ........................................................................................ .................... 22 5. references & relevant standards ............................................................................................. ............ 23 6. package & ordering information .............................................................................................. ............ 24 6.1 package dimensions ........................................................................................................ ............. 24 6.2 solder reflow profiles .................................................................................................... .............. 25 6.3 recommended pcb footprint .. ........... ........... ........... ........... ........... ........... ........... ........... ....... .. 26 6.4 packaging data ............................................................................................................ ................... 26 6.5 ordering information ...................................................................................................... ............. 26
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 5 of 27 1. pin out 1.1 pin assignment figure 1-1: 40-pin qfn agnd vco_vdd cp_vdd cp_res lf vco_gnd vco div_vdd reg_vdd agnd pd_vdd clkin clkin agnd in_vdd clkin_se agnd reset gs4915 40-pin qfn (top view) agnd clkout diff_out_vdd agnd d_vdd clkout_se se_vdd gnd lock ipsel gnd bypass autobypass d_vdd fctrl0 double skew_en gnd 1 2 3 4 5 6 7 8 9 10 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 11 12 13 14 15 16 17 18 19 20 ground pad (bottom of package) clkout agnd vco fctrl1
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 6 of 27 1.2 pin descriptions table 1-1: pin descriptions pin number name timing ty p e description 1 reg_vdd C power positive power supply connec tion for the internal voltage regulator. connect to filtered +3.3v dc. 2, 6, 9, 26, 30, 31, 40 agnd C power ground connection for analog blocks and ios. connect to clean analog gnd. 3 pd_vdd C power positive power supply connec tion for the phase detector. connect to filtered +1.8v dc. 4, 5 clkin, clkin C input clock signal inputs signal levels are cml/lvds compatible. a differential clock input signal is applied to these pins. 7 in_vdd C power positive power supply connection for the single-ended and differential input clock buffers. supplies clkin_se. connect to filtered +1.8v dc. 8 clkin_se C input clock signal input signal levels are lvcmos compatible. a single-ended video clock input signal is applied to this pin. 10 reset non synchronous input control signal input signal levels are lvcmos/lvttl compatible. see section 3.8.1 for operation. 11 ipsel non synchronous input control signal input signal levels are lvcmos compatible. selects which input clock is cleaned by the device. see section 3.2.3 for operation. 12, 20, 22 gnd C power ground connection for digital blocks and ios. connect to gnd. 13 bypass non synchronous input control signal input signal levels are lvcmos compatible. see manual bypass section 3.4.2 . 14 autobypass non synchronous input control signal input signal levels are lvcmos compatible. selects the bypass mode of the device. see manual bypass section 3.4.2 . 15 d_vdd C power positive power supply connection for digital block. connect to filtered +1.8v dc. the digital block includes pins 10 - 21. 17, 16 fctrl1, fctrl0 non synchronous input control signal inputs signal levels are lvcmos compatible. selects the frequency mode of the device. see section 3.4.1 for operation.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 7 of 27 18 double non synchronous input control signal input signal levels are lvcmos compatible. controls the output fre quency of the cleaned clock, for hd input clocks. see section 3.5 for operation. 19 skew_en non synchronous input control signal input signal levels are lvcmos compatible. selects the phase of the output clock with respect to the selected input clock. see section 3.6 for operation. 21 lock non synchronous outpu t status signal output signal levels are lvcmos compatible. this pin will be high when the output clock is locked to the selected input clock. it will be low otherwise. 23 se_vdd C power positive power supply connec tion for the single-ended clock driver. determines the output level of clkout_se. connect to filtered +1.8v dc or +3.3v dc. note: if the single-ended clock output is not used, this pin should be tied to ground. 24 clkout_se C outpu t clock signal output signal levels are lvcmos compatible. single-ended video clock output signal. see section 3.7.2 for operation. 25 d_vdd C power positive power supply connec tion for the single-e nded output clock buffer. connect to filtered +1.8v dc. note: if the single-ended clock output is not used, this pin should be tied to ground. 27 diff_out_vdd C power positive power supply conn ection for the lvds cl ock outputs. connect to filtered +1.8v dc. note: if the lvds clock outputs are not used, this pin should be tied to ground. 29, 28 clkout, clkout C outpu t clock signal output differential video clock output signal. this is the lowest jitter output of the device. see section 3.7.1 for operation. 32 div_vdd C power positive power supply connec tion for the divider block. connect to filtered +1.8v dc. 33,34 vco, vco analog input differential input for the exte rnal vco reference signal. when using the recommended vco, leave vco unconnected. see section 3.3.4 for operation. 35 vco_gnd C power ground reference for the external voltage controlled oscillator. connect to pins 2, 4, 6, and 8 of the go1555. table 1-1: pin descriptions (continued) pin number name timing ty p e description
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 8 of 27 36 lf analog outpu t control voltage for the external voltage controlled oscillator. connect to pin 5 of the go1555 via a low pass filter. see typical application circuit on page 22 . 37 cp_res analog input charge pump current control. connect to vco_gnd via a 10k resistor. 38 cp_vdd C power power supply for the internal charge pump block (nominally +2.5v dc). connect to vco_vdd (pin 39). 39 vco_vdd C power power supply for the external voltage controlled oscillator (+2.5v dc). connect to pin 7 of the go1555. this pin is an output. must be isolated from all other power supplies. C ground pad C power ground pad on bottom of package must be soldered to agnd plane of pcb. table 1-1: pin descriptions (continued) pin number name timing ty p e description
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 9 of 27 2. electrical characteristics 2.1 absolute maximum ratings 2.2 dc electrical characteristics parameter value supply voltage (se_vdd, reg_vdd) -0.3 to +4.0 v dc core supply voltage (all 1.8v supplies) -0.3 to +2.2 v dc input esd voltage 1 kv hbm storage temperature -50oc < t s < 125oc operating temperature -20oc < t a < 85oc note: absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these conditions or at any other condition beyond those indicated in the ac/dc electrical characteristic sections is not implied. table 2-1: dc electrical characteristics v dd = 1.8v 5%, 3.3v 5%; t a = -20oc to 85oc, unless otherwise shown parameter symbol conditions min ty p max units notes operating temperature range t a C -20 25 85 oc C power consumption (se_vdd = 1.8v nominal) p 1.8v 1.8v rail C 156 270 mw C 3.3v rail C 58 87 mw C power consumption (se_vdd = 3.3v nominal) p 3.3v 1.8v rail C 132 243 mw C 3.3v rail C 133 156 mw C +1.8v power supply voltage C C 1.71 1.8 1.89 v C +3.3v power supply voltage C C 3.135 3.3 3.465 v C +2.5v regulator output voltage C output load of 3-12ma 2.375 2.5 2.625 v C input voltage, logic low v il C C 0 0.35 x io_vdd v1,5 input voltage, logic high v ih C 0.65 x io_vdd 1.8 C v 1,5 output voltage, logic low v ol 1.8v or 3.3v operation C 0 0.4 v 2,3,5 output voltage, logic high v oh 1.8v operation 0.65 x io_vdd 1.8 C v 2,3,5 3.3v operation 0.65 x io_vdd 3.3 C v 2,3,5
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 10 of 27 2.3 ac electrical characteristics clock output drive current C 1.8v operation C 10 C ma 2,3,4 3.3v operation C 8 C ma 2,3,4 differential input common mode voltage v icm C 1.12 1.25 1.38 v C differential input swing v idiff C 240 350 460 mv C differential clock output common mode voltage v ocm 100 termination between clkout and clkout C1.45C v C differential clock output swing v odiff 100 termination between clkout and clkout 250 350 460 mv 6 notes: 1. for all lvcmos compatible inputs. 2. for lvcmos compatible output se_clk. 3. for lvcmos compatible output lock. 4. while still satisfying v ol max and v oh min. 5. io_vdd refers to the power supply that supplies the particular pin in question. d_vdd supplies pins 10- 21. in_vdd supplies cl kin_se. se_vdd supplies clkout_se. 6. differential swing as defined here: table 2-1: dc electrical characteristics (continued) v dd = 1.8v 5%, 3.3v 5%; t a = -20oc to 85oc, unless otherwise shown parameter symbol conditions min ty p max units notes v ocm 0v clkout clkout clkout - clkout v odiff +v odiff -v odiff table 2-2: ac electrical characteristics v dd = 1.8v 5%, t a = 0oc to 70oc, unless otherwise shown parameter symbol conditions min ty p max units notes input jitter tolerance ijt < 0.5hz -10 C 10 ui 1 0.5hz to 1hz -5 C 5 ui 1 1hz to 100hz -1 C 1 ui 1 > 100hz -0.1 C 0.1 ui 1
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 11 of 27 output jitter differential output C 100khz to 10mhz C 20 C ps C C unfiltered C 40 C ps C output jitter single-ended output C 100khz to 10mhz C 60 C ps C C unfiltered C 100 C ps C output duty cycle C differential output 45 C 55 % C single-ended output 40 C 60 % C differential clock output rise / fall time C 100 diff. load C 500 C ps C single-ended clock output rise / fall time C 10 pf load C 1200 C ps C input clock frequency C C 12 C 165 mhz C output clock frequency C C 12 C 165 mhz C lock detect time t lockd within 300ppm of reference frequency C C 500 us C unlock detect time t unlockd within 700ppm of reference frequency C C 500 us C lock time t lock CCC1s2 device latency C differential in, differential out, skew_en = low C1.2CnsC differential in, differential out, skew_en = high C 1.2 - t out /4 Cns C single ended in, single ended out, skew_en = low C3.5CnsC single ended in, single ended out, skew_en = high C 3.5 - t out /4 Cns C device latency difference C C C 750 C ps 3 notes: 1. one ui refers to one cycle of the input clk. 2. assuming power up has already occurred. 3. difference between cl eaning and bypass modes. table 2-2: ac electrical characteristics (continued) v dd = 1.8v 5%, t a = 0oc to 70oc, unless otherwise shown parameter symbol conditions min ty p max units notes
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 12 of 27 3. detailed description 3.1 functional overview the gs4915 provides a low jitter clock output when fed with an hd or sd video clock input. other input clock fr equencies betw een 12mhz and 165mhz ca n be automatically passed through to the gs4915 outputs. an internal 2:1 mux allows the user to select between a differential (cml/lvds compatible) or single-ended (lvcmos) input clock. both a single-ended lvcmos-compatible and an lvds-compatible differential output are provided. the gs4915 may operate in either auto or fixed frequency mode. in auto mode, the device will automatically clean the selected input clock if its frequency is found to be one of the supported sd or hd clock rates. in fixed mode, the user selects only one of these frequencies to be cleaned. in addition, the device allows the user to select between auto or manual bypass operation. in autobypass mode , the gs4915 will automatically bypass its cleaning stage and pass the input clock signal directly to the output whenever the device is unlocked which includes the case where the input frequency is something other than the five frequencies supported. in manual bypass mode, the input signal passes through directly to the output. the gs4915 can optionally double the outp ut frequency for 74.25mhz or 74.175mhz hd clocks in order to provide optimal jitter performance of some serializers. the gs4915 also provides the user with a 2- state skew control. the output clocks produced by the device may be advanced by ? of an output clk period in order to accommodate downstream setup and hold requirements. the gs4915 is designed to op erate with the go1555 vco. the gs4915 clock cleaner complements gennum's gs4911b clock and timing generator for im plementing a video genlock solu tion. whereas the gs4911b itself cleans low-frequency jitter, the gs4915 is designed to clean primarily the higher frequency jitter of clocks generated by the gs4911b. 3.2 clock inputs the gs4915 contains two separate input buffe rs to accept either a differential or single-ended input clock. the applied clock(s) can be any video clock needing cleaning, although typically it will be the video clock specifically used for serialization. the frequency of the applied clock sign al(s) must be betw een 12mhz and 165mhz. the clock input buffers use a separate powe r supply of +1.8v dc supplied via the in_vdd pin.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 13 of 27 3.2.1 differential clock input a differential lvds clock si gnal conforming to the ti a/eia-644-a standard may be ac-coupled to the clkin and clkin pins. if the gs4911b/10b/01b/00b is used, the pclk3 and pclk3 outputs from that device may be directly connected to the clkin and clkin inputs of the gs4915, respectively. the clkin and clkin input traces should be tightly-coupled with a controlled differential impedance of 100 . the pair should be terminated with 100 at the input to the device as no internal termination is provided. this input clock is selected as the one to be cleaned by the gs4915 when the ipsel pin is set low. the clock can be dc coupled if the levels are appropriate, but only ac coupling is recommended. these inputs are both lvds and cml compatible, and ac coupling is only required in cases where the common mode does not line up. 3.2.2 single-ended clock input a single-ended clock signal at from 1.8v - 3.3v cmos leve ls may be dc-coupled to the clkin_se pin. if the gs4911b/10b/01b/00b is used, the pclk 1 or pclk2 output from that device may be directly co nnected to the clkin_se input of the gs4915. 3.2.3 input clock selection an internal 2x1 input multiplexer is provided to allow switching between the differential and single-ended clock inputs using one external pin. when ipsel is set low, the differential clock at the clkin/clkin pins is selected as the one to be processed by the device. when ipsel is set high, the single-ended clock at the clkin_se pin is selected as the one to be processed. 3.2.4 unused clock inputs if the application will only provide a differential clock input, then the clkin_se input pin should be connected to agnd. if only a single-ended clock will be provided, then the clkin/clkin pins should be left unconnected. 3.3 clock cleaning pll to obtain a low-jitter output clock signal, the gs4915 uses a clock cleaning phase-locked loop. this block will always attempt to lock an external 1.485ghz vco signal to the selected input clock. internal dividers, set by the digital control block based on the frequency mode of the device (see section 3.4.1 ), are used to obtain the final output
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 14 of 27 clock of 27mhz (divide by 55), 74. 25mhz/74.175mhz (div ide by 20), or 148.5mhz/148.35mhz (divide by 10). 3.3.1 phase detector the gs4915's phase detector can identify ph ase misalignment be tween the selected input clock and the reference clock provided by the external vco, and correspondingly signal the charge pump to alter the vco control voltage. 3.3.2 charge pump the charge pump block of the pll is powered externally by +2.5v dc applied to cp_vdd. this is provided by the gs4915 itse lf at the vco_vdd pin. an external rc filter at the cp_vdd pin is recommended to reduce supply noise for best jitter performance. please refer to the typical application circuit on page 22 . an external resistance connected to the cp_res pin is used to set the charge pump reference current of the device. typically, the cp_res pin will be connected through 10k to vco_gnd. 3.3.3 loop filter the gs4915 pll loop filter is an external first order filt er formed by a series rc connection as shown in table 3-1: loop filter component values . the loop filter resistor value sets the bandwidth of the pll and the capacitor value controls its stability and lock time. a loop filter resistor value between 1 and 20 and a loop filter capacitor value between 1 f and 33 f are recommended. the gs4915 uses a non-linear, bang-bang, pll, therefore its bandwi dth scales linearly with the input jitter amplitude - greater inpu t jitter results in a smaller loop bandwidth causing more of the input jitter to be rejected. for a given input jitter amplitude, a smaller loop filter resistor produces a narr ower loop bandwidth. with an input jitter amplitude of 300ps, for example, the pll bandwidth can be adjusted from 2khz to 40khz by varying the loop filter resistor, as shown in the table below. for use with gs4911, a narrow loop ba ndwidth is recommended. increasing the loop filter capacitor value increases the stability of the pll, but results in a longer lock time. for loop filter resistors smaller than 7 , a capacitor value of 33 f is recommended, while larger resistor values can accommodate smaller capacitors. sample combinations of the loop filter resistor and capacitor values are shown in the table below, along with the re sulting loop bandwidth. addi tional loop bandwidths can be achieved by using different loop filter resistor values.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 15 of 27 3.3.4 external vco the gs4915 uses the external go1555 voltage controlled oscillator as part of its phase-locked loop. this external vco implementation was chosen to ensure superior jitter performance of the device. power for the external vco is generated entirely by the gs4915 from an on-chip voltage regulator. the internal regulator uses +3.3 v dc supplied at the reg_vdd pin to provide +2.5v at the vco_vdd pin. based on the control voltage output by the gs4915 on the lf pin, the go1555 produces a 1.485ghz reference signal for the pll. this signal must be run via a 50 controlled-impedance trace to the vco pin of the gs4915. the vco receiver block of the device will then convert this single-e nded signal into the differential 1.485ghz reference signal used by the clock cleaning pll. both the reference and controls signals should be referenced to the supplied vco_gnd, as shown in the recommended application circuit of the typical application circuit on page 22 . 3.4 modes of operation the gs4915 may operate in one of two possibl e frequency modes, and in one of three possible bypass modes. the combination of the frequency mode and bypass mode will determine the frequency and jitter of the output clock. 3.4.1 frequency modes the frequency mode of the device is determined entirely by the setting of the external fctrl[1:0] pins. table 3-1: loop filter component values loop filter r typical loop bandwidth* recommended loop filter c comments 1 2khz 33 f narrow bandwidth - provides maximum jitter reduction. long lock-time. 7 8khz 10 f 20 40khz 1 f wide bandwidth. fast lock-time. note: 1. *measured with 300ps pk-pk input jitter on clk. table 3-2: gs4915 frequency modes fctrl[1:0] frequency mode 00 auto 01 fixed C 27mhz 0.4%
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 16 of 27 in both auto and fixed frequency modes, the gs4915 will measure the selected input clock frequency to determine if it is in any of the following ranges: 27mhz 0.4%, 74.25mhz 0.4%, or 148.5mhz 0.4% (the se ranges include the 74.25mhz/1.001 and 148.5mhz/1.001 video cl ock frequencies). auto frequency mode when fctrl[1:0] = 00, the device will operate in auto frequency mode. in this mode, the gs4915 will automatically clea n the selected input clock if its frequency is found to be contained in any of the ranges listed above. the lock output pin will be high whenever the device has successfully locked its cleaning pll to the selected input clock. in auto frequency mode, lock will be high if the input clock frequency is 27mhz 0.4% , 74.25mhz 0.4%, or 148.5mhz 0.4%. if the input clock varies by more than 6.4%, the lock output pin will be low. between 0.4% and 6.4%, the device may lock or bypass, as shown in figure 3-1 . frequencies in this range should not be applied to the device. figure 3-1: locked, undefined and unlocked regions fixed frequency mode when fctrl[1:0] 00, the device will operate in fixed frequency mode. in this mode, the device will only clean the selected input clock if its frequency is found to be in the range defined by the particular setting of the fctrl[1:0] pins. 10 fixed C 74.25mhz 0.4% 11 fixed C 148.5mhz 0.4% table 3-2: gs4915 frequency modes fctrl[1:0] frequency mode locked undefined unlocked +0.4% -0.4% -6.4% +6.4%
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 17 of 27 for example, if fctrl[1:0] = 01, the gs49 15 will only clean the input clock if its frequency is 27mhz 0.4%; if fctrl[1:0] = 10, the gs4915 will only clean the input clock if its frequency is 74. 25mhz 0.4%; and if fctrl[1:0] = 11, the gs4915 will only clean the input clock if its frequency is 148.5mhz 0.4%. in fixed frequency mode, the lock output pin will be set high after the device has locked its cleaning pll to the selected input clock, and only if the input clock frequency matches the frequency selected by the setting of the fctrl[1:0] pins. otherwise, lock will be low. 3.4.2 bypass modes the bypass mode of the device is dete rmined by the setting of the external autobypass and bypass pins. autobypass mode when autobypass is low, the device will operate in autobypass mode. in this mode, the gs4915 will bypass its cleaning stage an d pass the selected input clock signal directly to the output whenever lock is low. manual bypass mode when autobypass and bypass are both high, the gs4915 will operate in manual bypass mode. in this mode, the gs4915 will bypass its cleaning stage and pass the selected input clock signal directly to the output. note: if operating in manual bypass mode, the lock output pin should be ignored. depending on the set frequency mode of the device and the detected frequency of the selected input clock, the cleaning pll of the device may achieve lock and so may set the lock pin high; however, the output clock will always be a copy of the input clock, and not the cleaned clock. forced output mode if autobypass is high and bypass is set low, the device will operate in forced output mode. in this mode, the cleaning stage of the device is never bypassed, and so the output clock will always be the clock output by the device's pll, even in an unlocked condition. table 3-3: gs4915 bypass modes autobypass bypass bypass mode 0 x autobypass mode 1 0 forced output mode 1 1 manual bypass mode note: 'x' indicates a "don't care" condition.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 18 of 27 when lock is high, the output clock will be low-jitter and locked to the selected input clock. but when lock is low in forced output mode, the output clock should not be used. 3.5 output clock frequency and jitter the frequency and jitter of the output clock are determined by: ? the frequency of the input clock, ? the differential or single-ended input and output clocks, ?the selected frequency mode, ? the selected bypass mode, and ? the setting of the double pin. when the double pin is set high, the output clock frequency will be double the input only when the selected input clock freque ncy is determined to be 74.25mhz 0.4%. otherwise, the setting of the double pin will have no effect on the frequency of the output clock. the output clock will be low jitter when the lock pin is high. the only exception to this is if operating in manual bypass mode, see section 3.4.2 . table 3-4 , table 3-5 , and table 3-6 summarize the output frequency and lock behaviour of the device given the frequency of the input clock, the selected frequency mode, and the setting of the double pin for autobypass, manual bypass, and forced output modes, respectively. in each table, 'x' indicates a "don't care" condition. table 3-4: output behaviour in autobypass mode fctrl[1:0] input double lock output auto [00] 27mhz x high 27mhz 74.25mhz 0 high 74.25mhz 1 high 148.5mhz 148.5mhz x high 148.5mhz other x low input fixed C 27mhz [01] 27mhz x high 27mhz 74.25mhz x low 74.25mhz 148.5mhz x low 148.5mhz other x low input
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 19 of 27 fixed C 74.25mhz [10] 27mhz x low 27mhz 74.25mhz 0 high 74.25mhz 1 high 148.5mhz 148.5mhz x low 148.5mhz other x low input fixed C 148.5mhz [11] 27mhz x low 27mhz 74.25mhz x low 74.25mhz 148.5mhz x high 148.5mhz other x low input table 3-5: output behaviour in manual bypass mode fctrl[1:0] input double lock output auto [00] 27mhz x high* 27mhz 74.25mhz x high* 74.25mhz 148.5mhz x high* 148.5mhz other x low input fixed C 27mhz [01] 27mhz x high* 27mhz 74.25mhz x low 74.25mhz 148.5mhz x low 148.5mhz other x low input fixed C 74.25mhz [10] 27mhz 0 low 27mhz 74.25mhz 0 high* 74.25mhz 148.5mhz 0 low 148.5mhz other 0 low input fixed C 148.5mhz [11] 27mhz x low 27mhz 74.25mhz x low 74.25mhz 148.5mhz x high* 148.5mhz other x low input *note: although lock = high under these conditions, the output clock will be a copy of the selected input clock and will have the jitter of the input clock. table 3-4: output behaviour in autobypass mode fctrl[1:0] input double lock output
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 20 of 27 3.6 output skew the gs4915 provides the user with the option of ad vancing the phase of the output clock from that of the input clock. this feature is controlled by the external skew_en pin. when skew_en is set low, the output clock will be delayed from the selected input clock only by the latency of the device. by setting skew_en = high, the user can advance the output clock from the selected input clock by one quarter of an output period, minus the latency of the device. please see figure 3-2 . table 3-6: output behaviour in forced output mode fctrl[1:0] input double lock output auto [00] 27mhz x high 27mhz 74.25mhz 0 high 74.25mhz 1 high 148.5mhz 148.5mhz x high 148.5mhz other x low last locked* fixed C 27mhz [01] 27mhz x high 27mhz 74.25mhz x low 27mhz 148.5mhz x low 27mhz other x low 27mhz fixed C 74.25mhz [10] 27mhz 0 low 74.25mhz 1 low 148.5mhz 74.25mhz 0 high 74.25mhz 1 high 148.5mhz 148.5mhz 0 low 74.25mhz 1 low 148.5mhz other 0 low 74.25mhz 1 low 148.5mhz fixed C 148.5mhz [11] 27mhz x low 148.5mhz 74.25mhz x low 148.5mhz 148.5mhz x high 148.5mhz other x low 148.5mhz *note: the output clock will remain within 5% of the last locked frequency if an input frequency other than 27mhz, 74.25mhz, or 148.5mhz is applied to the selected clock input. if operating under these conditions upon power-up, the output frequency will be 74.25mhz 5%.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 21 of 27 figure 3-2: output skew behaviour of gs4915 3.7 clock outputs the gs4915 presents both diffe rential and single-e nded clock outputs. when the lock output signal is high, these clock outputs wi ll be low-jitter and locked to the selected input clock. note: if in manual bypass mode, the lock pi n may be high although the output clock will always be a copy of the inpu t clock, and not the cleaned clock. the frequency of the differential and single-ended clock outputs will be identical and will be determined as described in section 3.5 . 3.7.1 differential clock output a cml-based driver is used to provide the differential clock output at the clkout and clkout pins. although this driver will output a signal amplitude that is compatible to the tia/eia-644 lvds stan dard, it has an incompatible co mmon mode level. therefore, ac-coupling and external biasing resistors are required if interfacing the differential clock outputs from the gs4915 to a true lvds receiver. the common mode is, however, compatible with the lvds inputs on most fpgas and can be dc coupled. this is the lowest-jitte r output of the gs4915. the differential clock output driver uses a separate power supply of +1.8v dc supplied via the diff_out_vdd pin. 3.7.2 single-ended clock output the single-ended output clock is present at the clkout_se pin. the signal will operate at either 1.8v or 3.3v cmos levels, as determined by the voltage applied to the se_vdd pin. the single-ended clock output pre-drive us es a separate power supply of +1.8v dc supplied via the d_vdd pin. 3.8 device reset 3.8.1 hardware reset in order to reset the gs4915 to their defaul ts conditions, the reset pin must be held low for a minimum of t reset = 0.5ms. device latency 1/4 clk period - device latency input clock output clock skew_en = low skew_en = high
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 22 of 27 4. typical application circuit figure 4-1: gs4915 typical application circuit 1v8_a 1v8_a 1v8_a 3v3_a s e_vdd 1v8_d 1v8_a 1v8_d lo c k p c lk_diff+ p c lk_diff- p c lk_ s e p c lkin+ p c lkin- c lkin_ s e re s et ip_ s el bypa ss man/auto c trl0 c trl1 double s kew_en v c o_ g nd v c o_vdd v c o_vdd v c o_ g nd v c o_ g nd v c o_ g nd v c o_ g nd v c o_ g nd v c o_ g nd g nd_d v c o_ g nd g nd_a g nd_d g nd_d g nd_d v c o_vdd s e_vdd (1v8_d or 3v3_d) 1v8_d g nd_d g nd_d g nd_d 3v3_a g nd_a g nd_a g nd_d 1v8_a g nd_a g nd_a g nd_a g nd_a g nd_a c 7 100n c 13 * c 19 100n r4 10k c 1 10u c 18 100n c 5 100n c 4 10u r5 100r c6 100n re g _vdd (3.3) 1 a g nd 2 pd_vdd (1.8) 3 c lkin 4 c lkin 5 a g nd 6 in_vdd(1.8) 7 c lkin_ s e 8 a g nd 9 re s et 10 ip s el 11 g nd 12 bypa ss 13 autobypa ss 14 d_vdd (1.8) 15 f c trl0 1 6 f c trl1 17 double 18 s kew_en 19 g nd 20 lo c k 21 g nd 22 s e_vdd (1.8 or 3.3) 23 c lkout_ s e 24 d_vdd (1.8) 25 a g nd 2 6 diff_out_vdd(1.8) 27 c lkout 28 c lkout 29 a g nd 30 a g nd 31 div_vdd(1.8) 32 v c o 33 v c o 34 v c o_ g nd 35 lf 3 6 c p_re s 37 c p_vdd (2.5) 38 v c o_vdd(2.5) 39 a g nd 40 g nd_pad u2 gs 4915 v c tr 5 g nd 4 g nd 8 g nd 2 v cc 7 o/p 1 n c 3 g nd 6 u1 g o1555 r2 150k c 3 10u r1 150k c 10 100n c 2 10u c 12 100n c 14 100n r3 * c 8 100n c 9 100n c 11 100n c 1 6 1u c 15 100n c 17 10n pin 1 pin 23 pin 25 pin 15 pin 3 pin 32 pin 27 pin 7 g nd_a * s ee ta b le 3-1: loop filter c omponent values to sele c t these values.
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 23 of 27 5. references & relevant standards table 5-1: references & relevant standards eia/jedec jesd8-b interface standard for 3v/3.3v supply digital integrated circuits eia/jedec jesd8-7 interface standard fo r 1.8-v supply digital integrated circuits tia/eia-644-a electrical characteristics of low voltage differential signalling (lvds) interface circuits smpte 240m-1999 1125-line high definition production systems - signal parameters smpte 259m-1997 10-bit 4:2:2 component and 4fsc composite digital signals - serial digital interface smpte 274m-1998 1920 x 1080 scanning and analog and parallel digital interfaces for multiple picture rates smpte 292m-1998 bit-serial digital interface for high-definition television systems smpte 294m-1997 720 x 483 active line at 59.94-hz progressive scan production - bit-serial interfaces smpte 295m-1997 1920 x 1080 50 hz - scanning and interfaces smpte 296m-1997 1280 x 720 scanning, analog and digital representation and analog interface smpte rp 184-2004 specification of jitter in bit-serial digital systems smpte rp 211-2000 implementation of 24p, 25p and 30p segmented frames for 1920 x 1080 production format itu-r bt.656 interface for digital component video signals in 525-line and 625-line television systems itu-r bt.709-4 parameter values for the hdtv standards for production and international program exchange
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 24 of 27 6. package & ordering information 6.1 package dimensions 0.30@45 chamfer detail b 4.450.05 0.500.05 4.450.05 datum a datum b 0.50 0.230.05 40x 0.10 m 0.05 ca b m c pin 1 6.00 6.00 a b 2x 0.15 c 2x 0.15 c 0.02 +0.03 - 0.03 0.900.10 seating plane 40x 0.08 c 0.10 c c 0.20 ref datum a or b terminal tip detail b 0.50/2 0.50 marking area top view bottom view 45o1o 0.310.05
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 25 of 27 6.2 solder reflow profiles the device is manufactured with matte-sn terminations and is compatible with both standard eutectic and pb-free solder reflow profiles. the recommended standard eutectic reflow profile is shown in figure 6-1 . msl qualification was performed using the maximum pb-free reflow profile shown in figure 6-2 . figure 6-1: standard eutectic solder reflow profile figure 6-2: maximum pb-free solder reflow profile (preferred) 25c 100c 150c 183c 230c 220c time temperature 6 min. max 120 sec. max 60-150 sec. 10-20 sec. 3c/sec max 6c/sec max 25c 150c 200c 217c 260c 250c time temperature 8 min. max 60-180 sec. max 60-150 sec. 20-40 sec. 3c/sec max 6c/sec max
gs4915 clockcleaner? data sheet 39145 - 5 june 2009 26 of 27 6.3 recommended pcb footprint note: suggested dimensions only. final dimensions shou ld conform to customer design rules 1 and process optimizations. 6.4 packaging data 6.5 ordering information note: all dimensions are in millimeters. 5.60 5.60 4.45 4.45 0.50 0.25 0.65 center pad parameter value package type 6mm x 6mm 40-pin qfn moisture sensitivity level 3 junction to case thermal resistance, j-c 19.9c/w junction to air thermal resistance, j-a (at zero airflow) 34.9c/w junction to board thermal resistance, j-b 12.5c/w psi, 0.5c/w pb-free and rohs compliant yes part number package temperature range gs4915 ? ine3 pb-free 40-pin qfn -20c to 85c
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