datasheet dvd/mpeg clock source mk2746 idt? dvd/mpeg clock source 1 mk2746 rev c 051310 description the mk2746 is a low cost, low jitter, high performance clock synthesizer for dvd and other mpeg2 based applications. using analog phase locked loop (pll) techniques, the device accepts a 27 mhz fundamental mode crystal or clock input to produce multiple output clocks including the processor clock, audio clock, bus driver clock, sdram clock and a video clock. the audio clocks are frequency locked to the 27 mhz input using our patented zero ppm error techniques, allowing audio and video to track exactly, thereby eliminating the need for large buffer memory. idt manufacturers the largest variety of dvd, set top box, and multimedia clock synthes izers for all applications. block diagram features ? packaged in 16 pin tssop ? operating voltage of 3.3 v ? provides tight jitter controlled selectable processor clock per table. ? provides selectable audio clock per table. ? provides fixed outputs of 27 mhz (video), 50 mhz (dsp/bus clock) and 133.33 mhz (sdram). ? advanced, low power, sub-micron cmos process 27m video clock clock buffer/ crystal ocsillator ps1:0 133.33 m sdram clock processor (tight jitter) vdd gnd pll / clock circuit 3 2 50m bus clock audio as1:0 x1 x2 27 mhz crystal or clock
mk2746 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 2 mk2746 rev c 051310 pin assignment clock output select table in mhz 0 = connect directly to gnd 1 = connect directly to vdd pin descriptions 12 1 11 2 10 x2 vdd 3 9 x1/iclk 4 vdd 27m 5 gnd 6 as0 7 pclk 8 ps0 aclk as1 vdd 133.33m gnd ps1 50m 16 15 14 13 16 pin (173 mil) tssop as1 as0 audio clk 0 0 12.288 0 1 11.2896 1 0 18.432 1 1 8.192 ps1 ps0 processor clk 00 66.66 01 41.66 10 50 11 58.33 pin number pin name pin type pin description 1 x2 input connect to a 27 mhz fundamental mode crystal. leave open for clock input. 2 x1/iclk input connect to a 27 mhz fundamental mode crystal or clock. 3 vdd power connect to +3.3 v. 4 gnd power connect to ground 5 pclk output processor clock output. determin ed by the status of ps1, ps0 per table above. 6 ps0 input processor clock select 0. se lects processor clock per table above. 7 133.33m output sdram clock output. 8 ps1 input processor clock select 1. se lects processor clock per table above. 9 50m output 50 mhz clock output. 10 gnd power connect to ground. 11 vdd power connect to +3.3 v. 12 as1 input audio clock select 1. selects audio clock per table above. 13 aclk output audio clock output deter mined by the status of ps1, ps0. 14 as0 input audio clock select 0. selects audio clock per table above. 15 27m output 27 mhz clock output. 16 vdd power connect to +3.3 v.
mk2746 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 3 mk2746 rev c 051310 external component selection the mk2746 requires a minimum number of external components for proper operation. decoupling capacitors decoupling capacitors of 0.01 f should be connected between vdd and gnd as close to the mk2746 as possible. for optimum device performance, the decoupling capacitors should be mounted on the component side of the pcb. avoid the use of vias in the decoupling circuit. series termination resistor when the pcb traces between the clock outputs and the loads are over 1 inch, series termination should be used. to series terminate a 50 ? trace (a commonly used trace impedance) place a 33 ? resistor in series with the clock line, as close to the clock output pin as possible. the nominal impedance of the clock output is 20 ? . crystal tuning load capacitors for a crystal input, a parallel resonant fundamental mode crystal should be used. crystal capacitors must be connected between each of the pins x1 and x2 to ground. the value (in pf) of these crystal caps should equal (cl-6)*2. in this equation cl is equal to the crystal load capacitance in pf. as an example, for a crystal with an 18 pf load capacitance, each crystal capacitor would be 24 pf [(18-6)*2=24]. pcb layout recommendations for optimum device performance and lowest output phase noise, the following guidelines 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 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. distance of the ferrite bead and bulk decoupling from the device is less critical. 2) the external crystal should be mounted just next to the device with short traces. the x1 and x2 traces should not be routed next to each other with minimum spaces, instead they should be separated and away from other traces. 3) to minimize emi the 33 ? series termination resistor, if needed, should be placed close to the clock output. 4) an optimum layout is one with all components on the same side of the board, minimizing vias through other signal layers (the ferrite bead and bulk decoupling capacitor can be mounted on the back). other signal traces should be routed away from the mk2746. this includes signal traces just underneath the device, or on layers adjacent to the ground plane layer used by the device. absolute maximum ratings stresses above the ratings listed below can cause perm anent damage to the mk2746. 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. 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 soldering temperature 260 c
mk2746 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 4 mk2746 rev c 051310 recommended operation conditions dc electrical characteristics vdd=3.3 v 10% , ambient temperature 0 to +70 c, unless stated otherwise ac electrical characteristics vdd = 3.3 v 10% , ambient temperature 0 to +70 c, unless stated otherwise note 1: measured with 15 pf load. parameter min. typ. max. units ambient operating temperature 0 +70 c power supply voltage (measured in respect to gnd) +3.0 +3.6 v parameter symbol conditions min. typ. max. units operating voltage vdd 3.0 3.6 v input high voltage v ih input selects 2.0 v input low voltage v il input selects 0.8 v input high voltage v ih iclk (vdd/2)-1 vdd/2 v input low voltage v il iclk vdd/2 (vdd/2)+1 v output high voltage v oh i oh = -12 ma 2.4 v output low voltage v ol i ol = 12 ma 0.4 v output high voltage (cmos level) v oh i oh = -4 ma vdd-0.4 v operating supply current idd no load 40 ma short circuit current i os 70 ma input capacitance c in 5pf nominal output impedance z out 20 ? on chip pull-up resistor r pu as1, as0 pins 120 k ? ps1 pin 510 k ? parameter symbol conditions min. typ. max. units input frequency 27 mhz output rise time t or 20% to 80% of vdd, note 1 1.0 1.8 ns output fall time t of 80% to 20% of vdd, note 1 1.0 1.8 ns output clock duty cycle t d at vdd/2, note 1 40 50 60 % maximum output jitter, short term, peak to peak t j pclk output, note 1 + 100 ps maximum output jitter, short term, peak to peak t j all clocks, except pclk, note 1 + 200 ps maximum output jitter, long term, peak to peak t j 1000 cycles, except aclk, note 1 750 ps
mk2746 dvd/mpeg clock source vcxo and synthesizer idt? dvd/mpeg clock source 5 mk2746 rev c 051310 package outline and package dimensions (16-pin tssop, 4.40 mm body, 0.65 mm pitch) package dimensions are kept current with jedec publication no. 95 ordering information 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 MK2746GLF mk2746gl tubes 16-pin tssop 0 to +70 c MK2746GLFt mk2746gl tape and reel 16-pin tssop 0 to +70 c index area 1 2 16 d e1 e seating plane a 1 a a 2 e - c - b aaa c c l *for reference only. cont rolling dimensions in mm. millimeters inches* symbol min max min max a--1.20--0.047 a1 0.05 0.15 0.002 0.006 a2 0.80 1.05 0.032 0.041 b 0.19 0.30 0.007 0.012 c 0.09 0.20 0.0035 0.008 d 4.90 5.1 0.193 0.201 e 6.40 basic 0.252 basic e1 4.30 4.50 0.169 0.177 e 0.65 basic 0.0256 basic l 0.45 0.75 0.018 0.030 0 8 0 8 aaa -- 0.10 -- 0.004
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