october 2003 p2781/82/84 rev 1.0 alliance semiconductor 2575, augustine drive ? santa clara, ca ? tel: 408.855.4900 ? fax: 408.855.4999 ? www.alsc.com notice: the information in this document is subject to change without notice. general purpose emi reduction ic features ? provides up to 15 db of emi suppression ? fcc approved method of emi attenuation ? generates a 1x, 2x, and 4x low emi spread spectrum clock of the input frequency ? input frequency range from 3 to 78 mhz ? external loop filter for spread % adjustment ? spreading ranges from 0.25% to 5.0% ? ultra low cycle-to-cycle jitter ? zero-cycle slip ? 3.3v operating voltage range ? 10 ma output drives ? ttl or cmos compatible outputs ? ultra-low power cmos design ? available in 8 pin soic and tssop ? available for industrial and automotive temperature ranges. product description the p278xx is a versatile spread spectrum frequency modulator designed specifically for digital camera and other digital video and imaging applications. the p278xx reduces electromagnetic interference (emi) at the clock source, which provides system wide reduction of emi of all clock dependent signals. the p278xx allows significant system cost savings by reducing the number of circuit board layers and shielding that are traditionally required to pass emi regulations. the p278xx uses the most efficient and optimized modulation profile approved by the fcc. the p278xx modulates the output of a single pll in order to ?spread? the bandwidth of a synthesized clock and, more importantly, decreases the peak amplitudes of its harmonics. this results in significantly lower system emi compared to the typical narrow band signal produced by oscillators and most frequency generators. lowering emi by increasing a signal?s bandwidth is called spread spectrum clock generation. applications the p278xx is targeted towards mfp, xdsl, fax modem, set-top box, usb controller, dsc, and embedded systems. block diagram
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 2 of 9 notice: the information in this document is subject to change without notice. pin configuration pin description (p278xa) pin# pin name type description 1 xin/clkin i connect to crystal or clock input. 2 xout i crystal output 3 fs1 i digital logic input used to select input frequency range (see the input frequency selection table). this pin has an internal pull-up resistor. 4 lf i external loop filter for the pll. by changing the value of the crc circuit, the percentage spread can be adjusted accordingly. see the loop filter selection table for detail value. 5 vss i ground connection. c onnect to system ground. 6 modout o spread spectrum clock output. 7 fs0 i digital logic input used to select input frequency range (see the input frequency selection table). this pin has an internal pull-up resistor. 8 vdd p connect to +3.3 v input frequency selection table output frequency scaling (mhz) fs1 fs0 input (mhz) p2781x p2782x p2784x modulation rate (khz) 0 0 3 to 9 3 to 9 6 to 18 12 to 36 fin / 128 0 1 10 to 19 10 to 19 20 to 38 40 to 76 fin / 256 1 0 20 to 38 20 to 38 40 to 76 80 to 152 fin / 512 1 1 39 to 78 39 to 78 78 to 156 156 to 312 fin / 1024
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 3 of 9 notice: the information in this document is subject to change without notice. loop filter selection table vdd 3.3v contact alliance for loop values that are not listed in the table and for component selection values for industrial and automotive temperatures. bw = 0.50% 1 bw = 0.75% 1 bw = 1.00% 1 bw = 1.25% 1 input mhz fs1 fs0 c1 (pf) c2 (pf) r1 (ohm) c1 (pf) c2 (pf) r1 (ohm) c1 (pf) c2 (pf) r1 (ohm) c1 (pf) c2 (pf) r1 (ohm) 3 0 0 270 330,000 220 270 330,000 300 270 100,000 390 560 100,000 510 4 0 0 270 100,000 270 270 100,000 390 270 100,000 560 560 100,000 680 5 0 0 270 100,000 390 270 100,000 560 270 100,000 750 560 100,000 910 6 0 0 270 100,000 510 270 100,000 750 270 10,000 1,000 680 6,800 1,200 7 0 0 270 100,000 620 270 100,000 1,000 270 5,600 1,200 330 3,300 1,200 8 0 0 270 100,000 820 270 100,000 1,200 270 12,000 2,200 680 6,800 2,200 9 0 0 270 100,000 1,000 270 100,000 1,500 270 5,600 2,200 270 2,700 2,200 10 0 1 270 100,000 330 270 100,000 510 270 100,000 750 560 100,000 910 11 0 1 270 100,000 390 270 100,000 560 270 100,000 866(1%) 560 100,000 1,100 12 0 1 270 100,000 510 270 100,000 750 270 10,000 1,000 680 6,800 1,200 13 0 1 270 100,000 560 270 100,000 820 270 12,000 1,200 470 4,700 1,200 14 0 1 270 100,000 620 270 100,000 1,000 270 5,600 1,200 330 3,300 1,200 15 0 1 270 100,000 750 270 100,000 1,100 270 3,900 1,200 330 3,300 1,500 16 0 1 270 100,000 820 270 100,000 1,200 270 12,000 2,200 680 6,800 2,200 17 0 1 270 100,000 910 270 100,000 1,300 270 10,000 2,200 390 3,900 2,200 18 0 1 270 100,000 1,000 270 100,000 1,500 270 5,600 2,200 270 2,700 2,200 19 0 1 270 100,000 1,200 270 100,000 1,600 270 3,300 2,200 270 2,700 2,700 20 0 0 270 100,000 330 270 100,000 560 270 100,000 750 560 100,000 910 21-22 1 0 270 100,000 390 270 100,000 620 270 100,000 866 (1%) 560 100,000 1,100 23-24 1 0 270 100,000 510 270 100,000 750 270 10,000 1,000 680 6,800 1,200 25-26 1 0 270 100,000 560 270 100,000 820 270 12,000 1,200 470 4,700 1,200 27-28 1 0 270 100,000 620 270 100,000 1,000 270 6,800 1,200 330 3,300 1,200 29-30 1 0 270 100,000 750 270 100,000 1,100 270 3,900 1,200 330 3,300 1,500 31-32 1 0 270 100,000 820 270 100,000 1,200 270 12,000 2,200 680 6,800 2,200 33-34 1 0 270 100,000 910 270 100,000 1,300 270 10,000 2,200 390 3,900 2,200 35-36 1 0 270 100,000 1,000 270 100,000 1,500 270 5,600 2,200 270 2,700 2,200 37-38 1 0 270 100,000 1,200 270 100,000 1,600 270 3,300 2,200 270 2,700 2,700 39-42 1 1 270 100,000 330 270 100,000 560 270 100,000 750 560 100,000 910 43-46 1 1 270 100,000 390 270 100,000 620 270 100,000 866 (1%) 560 100,000 1,100 47-50 1 1 270 100,000 510 270 100,000 750 270 10,000 1,000 680 6,800 1,200 51-54 1 1 270 100,000 560 270 100,000 820 270 12,000 1,200 470 4,700 1,200 55-58 1 1 270 100,000 620 270 100,000 1,000 270 6,800 1,200 330 3,300 1,200 59-62 1 1 270 100,000 750 270 100,000 1,100 270 3,900 1,200 330 3,300 1,500 63-66 1 1 270 100,000 820 270 100,000 1,200 270 12,000 2,200 680 6,800 2,200 67-70 1 1 270 100,000 910 270 100,000 1,300 270 8,200 2,200 390 3,900 2,200 71-74 1 1 270 100,000 1,000 270 100,000 1,600 270 5,600 2,200 270 2,700 2,200 75-78 1 1 270 100,000 1,200 270 100,000 1,800 270 3,300 2,200 270 2,700 2,700 1 the bw value is representative of typical conditions
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 4 of 9 notice: the information in this document is subject to change without notice. spread spectrum selection the p278xa performs zero cycle slip when set at low percentage spreading. this allows no occurrence of system timing erro r. the optimal setting should minimize system emi to the fullest without affecting system performa nce. the spreading is described as a percentage deviation of the center frequency. (note: the center frequency is the frequency of the external reference input on clkin, pin 1.) the p2781a is designed for pc peripheral, networking, notebook pc, and lcd monitor applications. it is optimized for operation between 3 to 78 mhz range. in the following application schematic example, the p2781a spread percentage selection is determined by the external lf value specified in the loop filter selection table. the input frequency select ion table specifies the input frequency range. the external lf allows the user to fine tune the sp read percentage to optimize the emi reduction benefits of the spread spectrum. note: both logic input pins fs1 and fs0 have to be connected to either v dd or vss. do not leave them floating.
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 5 of 9 notice: the information in this document is subject to change without notice. absolute maximum ratings symbol parameter rating unit v dd , v in voltage on any pin with respect to gnd -0.5 to + 7.0 v t stg storage temperature -65 to +125 c t a operating temperature 0 to +70 c dc electrical characteristics symbol parameter min typ max unit v il input low voltage gnd ? 0.3 ? 0.8 v v ih input high voltage 2.0 ? v dd +0.3 v i il input low current (internal input pull-up resistor on fs0 and fs1) ? 60 ? a i ih input high current (internal input pull-up resistor on fs0 and fs1) ? 0 ? a i xol xout output low current ? 10 ? ma i xoh xout output high current ? 10 ? ma v ol output low voltage (v dd = 3.3 v, i ol = 20 ma) ? ? 0.4 v v oh output high voltage (v dd = 3.3 v, i oh = 20 ma) 2.5 ? - v i dd static supply current - 3 - ma i cc typical dynamic supply current (25 pf scope probe loading) 5.2 at 3 mhz ? 21.2 at 82 mhz ma v dd operating voltage 3.0 3.3 3.6 v ac electrical characteristics symbol parameter min typ max unit f in input frequency: p278xx 3 78 mhz f out output frequency: p2781x p2782x p2784x 3 6 12 78 156 312 mhz t lh p278xx output rise time (measured at 0.8 v to 2.0 v, 25 pf scope probe loading) 1 ns t hl p278xx output fall time (measured at 2.0 v to 0.8 v, 25 pf scope probe loading) 1 ns t jc p2781x jitter (cycle to cycle, 6sigma, 1000 sweeps, 0.5% spread, i/o frequency = 16 mhz) 250 ps t d p2781x output duty cycle deviation (error from 50% duty cycle, 25 pf scope probe loading) 1 at 3 mhz 2 at 82 mhz % ? f p278xx frequency deviation tolerance from bw% stated in the loop filter selection table -20 0 +20 %
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 6 of 9 notice: the information in this document is subject to change without notice. package information mechanical package outline 8-pin soic dimensions in inches dimensions in millimeters symbol min nor max min nor max a 0.057 0.064 0.071 1.45 1.63 1.80 a1 0.004 0.007 0.010 0.10 0.18 0.25 a2 0.053 0.061 0.069 1.35 1.55 1.75 b 0.012 0.016 0.020 0.31 0.41 0.51 c 0.004 0.006 0.01 0.10 0.15 0.25 d 0.186 0.194 0.202 4.72 4.92 5.12 e 0.148 0.156 0.164 3.75 3.95 4.15 e 0.050 bsc 1.27 bsc h 0.224 0.236 0.248 5.70 6.00 6.30 l 0.012 0.020 0.028 0.30 0.50 0.70 a 0 5 8 0 5 8 note: controlling dimensions are millimeters soic - 0.074 grams unit weight
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 7 of 9 notice: the information in this document is subject to change without notice. mechanical package outline 8-pin tssop dimensions in inches dimensions in millimeters symbol min nor max min nor max a 0.047 1.10 a1 0.002 0.006 0.05 0.15 a2 0.031 0.039 0.041 0.80 1.00 1.05 b 0.007 0.012 0.19 0.30 c 0.004 0.008 0.09 0.20 d 0.114 0.118 0.122 2.90 3.00 3.10 e 0.169 0.173 0.177 4.30 4.40 4.50 e 0.026 bsc 0.65 bsc h 0.244 0.252 0.260 6.20 6.40 6.60 l 0.018 0.024 0.030 0.45 0.60 0.75 a 0 5 8 0 5 8 note: controlling dimensions are millimeters tssop -0.034 grams unit weight
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 8 of 9 notice: the information in this document is subject to change without notice. ordering codes ordering number marking package type qty / reel temperature x278xa-08st x278xa 8 pin soic, tube see flow x278xa-08sr x278xa 8 pin soic, tape & reel 2,500 see flow x278xa-08tt x278xa 8 pin tssop, tube see flow x278xa-08tr x278xa 8 pin tssop, tape & reel 2,500 see flow x278xb-08tt x278xb 8 pin tssop, tube see flow x278xb-08tr x278xb 8 pin tssop, tape & reel 2,500 see flow device ordering information x278xx x- 08 xx package: st ? soic, tube sr - soic, t/r tt ? tssop, tube tr - tssop, t/r f = pb free device number flow: p = commercial temperature range (0c to 70c) i = industrial temperature range (-25c to 85c) a = automotive tem p erature ran g e ( -40c to 125c ) pin count
october 2003 p2781/82/84 rev 1.0 general purpose emi reduction ic 9 of 9 notice: the information in this document is subject to change without notice. ? copyright 2003 alliance semiconductor corporation. all rights reserved. our three-point logo, our name and intelliwatt are trademarks or registered trademarks of alliance. all other brand and product names may be the trademarks of their respective companies. alliance reserves the right to make ch anges to this document and its products at any time without notice. alliance assumes no responsibility for any errors t hat may appear in this document. the data contained herein represents alliance's best data and/or estimate s at the time of issuance. alliance rese rves the right to change or correct this data at any time, without notice. if the product described herein is under development, significant changes to these specifications are possible. the information in this product data sheet is intended to be general descriptive information for potential customers and users, and is not in tended to operate as, or provide, any guarantee or warrantee to any user or customer. alliance does not assume any responsibility or lia bility arising out of the applic ation or use of any product described herein, and disclaims any express or implied warrant ies related to the sale and/or use of alliance products including liability or warranties related to fitness for a particular purpose, mercha ntability, or infringement of any intellec tual property rights, except as express agreed to in alliance's terms and conditions of sale (which are available from alliance). all sales of alliance products are made exclusively according to alliance's terms and conditions of sale. the purchase of products from alliance does not convey a license under any pa tent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of alli ance or third parties. alliance does not aut horize its products for use as critical components in life-supporting systems where a malfunction or fa ilure may reasonably be expected to result in significant injury to the user, and the inclusion of alliance products in such life-supporting systems implies that the manufacturer assumes all risk of such use and agrees to indemnify alliance against all claims arising from such use. alliance semiconductor corporation 2595, augustine drive, santa clara, ca 95054 tel# 408-855-4900 fax: 408-855-4999 www.alsc.com copyright ? alliance semiconductor all rights reserved part number: p2781/82/84 document version: 1.0
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