datasheet dvd/mpeg clock source mk2745-21 idt? dvd/mpeg clock source 1 mk2745-21 rev f 051310 description the mk2745-21 is a low-cost, low-jitter, high-performance clock synthesizer for dvd and other mpeg 2-based applications. using analog phase-locked loop (pll) techniques, the device accepts a 27 mhz fundamental mode crystal or clock input to produce multiple audio output clocks, a processor clock, the processor clock divided by two, 27 mhz, 24.576 mhz, and a selectable audio clock. the audio clocks are frequency-locked to the 27 mhz using our patented zero ppm error techniques. this allows audio and video to track exactly, thereby eliminating the need for large buffer memory. idt manufactures a large variety of dvd, set-top box, and multimedia clock synthesizers for all applications. consult idt to eliminate crystals and oscillators from your board. features ? packaged in a 16-pin narrow (150 mil) soic ? ideal for luxsonor?s dvd solutions ? 3.3 v upgrade to the mk2744 ? patented zero ppm audio clock error for 256x and 384x sampling rates ? selectable audio sampling frequencies support 32, 44.1, and 48 khz in most dacs ? 27 mhz fundamental crystal or clock input ? eight selectable processor frequencies ? fixed clocks of 27 and 24.576 mhz ? zero ppm in all clocks ? 25 ma output drive c apability at ttl levels ? advanced, low-power, sub-micron cmos process ? operating voltage of 3.0 v to 5.5 v ? see also the mk2712 for ntsc/pal clocks block diagram 27 mhz clock buffer/ crystal ocsillator ps1:0 24.576 mhz vdd gnd clock synthesis and control circuitry 2 2 processor clock audio clock as2:0 x1 x2 27 mhz crystal or clock 3 2 /2 pclk/2
mk2745-21 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 2 mk2745-21 rev f 051310 pin assignment audio clock (mhz) decodingtable processor clock (mhz) 0 = connect directly to ground 1 = connect directly to vdd pin descriptions 1 2 3 gnd 4 x2 5 6 24.576m 7 8 pclk/2 vdd 27m pclk ps0 aclk as0 x1/iclk 16 ps1 vdd as2 gnd as1 15 14 13 12 11 10 9 16-pin (150 mil) soic as2 as1 as0 aclk 0 0 0 12.288 0 0 1 11.2896 0108.192 0 1 1 24.576 1008.192 1 0 1 16.9344 1 1 0 18.432 1 1 1 11.2896 ps1 ps0 pclk pclk/2 0 0 66.66 33.33 01 80 40 10 50 25 11 60 30 pin number pin name pin type pin description 1 ps1 input processor clock select 1. selects processor clock outputs per table above. 2 x2 xo crystal connection. connect to 27 mhz crystal. leave unconnected for clock input. 3 x1/iclk xi crystal connection. connect to 27 mhz crystal or to a 27 mhz input clock. 4 vdd power connect to +3.3 v or +5 v. must be same as other vdd. 5 gnd power connect to ground. 6 aclk output audio clock output. determined by status of as2, as1, as0. see table above. 7 pclk output processor clock output. determined by status of ps1, ps0. see table above. 8 as2 input audio clock select 2. selects audio clock on pin 6 per table above. 9 as0 input audio clock select 0. selects audio clock on pin 6 per table above. 10 27m output 27 mhz clock output. 11 gnd power connect to ground. 12 as1 input audio clock select 1. selects audio clock on pin 6 per table above. 13 vdd power connect to +3.3 v or +5 v. must be same as other vdd.
mk2745-21 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 3 mk2745-21 rev f 051310 external components the mk2745-21 requires a minimum number of external components for proper operation. decoupling capacitors of 0.1f should be connected between vdd and gnd, as close to the mk2745-21 as possible. a series termination resistor of 33 ? may be used for each clock output. if a clock input is not used, the 27 mhz crystal must be connected as close to the chip as possible. the crystal should be a fundamental mode (do not use third overtone), parallel resonant, 50 ppm or better. crystal capacitors sh ould be connected from pins x1 to ground and x2 to ground. the value of these capacitors is given by the follo wing equation, where cl is the crystal load capacitance: crystal caps (pf) = (cl-6) x 2. so, for a crystal with 16 pf load capacitance, two 20 pf caps should be used. absolute maximum ratings stresses above the ratings listed below can cause permanent damage to the mk2745-21. these ratings, which are standard values for idt 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. 14 pclk/2 output processor clock divided by two output. determined by status of ps1, ps0. see table above. 15 24.576m output 24.576 mhz clock output. 16 ps0 input processor clock select 0. selects processor clock outputs per table above. pin number pin name pin type pin description item rating supply voltage, vdd 7 v all inputs and outputs -0.5 v to vdd+0.5 v ambient operating temperature 0 to +70 c storage temperature -65 to +150 c junction temperature 125 c soldering temperature 260 c
mk2745-21 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 4 mk2745-21 rev f 051310 recommended operation conditions dc electrical characteristics vdd = 5.0 v (unless noted) , temp 0 to +70 c note 1: with processor clock at 50 mhz and aclk at 16.93 mhz. ac electrical characteristics vdd = 5.0 v (unless noted) , temp 0 to +70 c thermal characteristics parameter min. typ. max. units ambient operating temperature 0 +70 c power supply voltage (measured in respect to gnd) +3.0 +5.5 v parameter symbol conditions min. typ. max. units operating voltage vdd 3.0 5.5 v input high voltage v ih x1/iclk pin only (vdd/2)+1 v input low voltage v il x1/iclk pin only (vdd/2)-1 v input high voltage v ih 2v input low voltage v il 0.8 v output high voltage v oh i oh = -25 ma 2.4 v output low voltage v ol i ol = 25 ma 0.4 v output high voltage v oh i oh = -8 ma vdd-0.4 v operating supply current idd no load, note 1 37 ma short circuit current i os each output 100 ma input capacitance c in 7pf parameter symbol conditions min. typ. max. units input frequency 27 mhz output clock rise time t or 0.8 to 2.0 v 1.5 ns output clock fall time t of 2.0 to 0.8 v 1.5 ns output clock duty cycle at vdd/2 40 60 % frequency error 0 1 ppm absolute jitter, short term variation from mean 200 ps parameter symbol conditions min. typ. max. units thermal resistance junction to ambient ja still air 120 c/w ja 1 m/s air flow 115 c/w ja 3 m/s air flow 105 c/w thermal resistance junction to case jc 58 c/w
mk2745-21 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 5 mk2745-21 rev f 051310 package outline and package dimensions (16-pin soic, 150 mil. narrow body) package dimensions are kept current with jedec publication no. 95 ordering information ?lf? denotes pb (lead) free package 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 paten ts or other rights of third parties, which would resul t from 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 idt. idt reserves th e 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 MK2745-21SLF 2745-21slf tubes 16-pin soic 0 to 70 c MK2745-21SLFtr 2745-21slf tape and reel 16-pin soic 0 to 70 c index area 1 2 16 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 9.80 10.00 .3859 .3937 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
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