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| October 2003 rev 1.0 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 Block Diagram P2781/82/84 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. 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. October 2003 rev 1.0 Pin Configuration P2781/82/84 Pin Description (P278XA) Pin# 1 2 3 4 5 6 7 8 Pin Name XIN/CLKIN XOUT FS1 LF VSS ModOUT FS0 VDD Type I I I I I O I P Description Connect to crystal or clock input. Crystal output Digital logic input used to select input frequency range (see the Input Frequency Selection Table). This pin has an internal pull-up resistor. 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. Ground Connection. Connect to system ground. Spread Spectrum Clock Output. Digital logic input used to select input frequency range (see the Input Frequency Selection Table). This pin has an internal pull-up resistor. Connect to +3.3 V Input Frequency Selection Table FS1 0 0 1 1 FS0 0 1 0 1 Input (MHz) 3 to 9 10 to 19 20 to 38 39 to 78 Output Frequency Scaling (MHz) P2781X P2782X P2784X 3 to 9 6 to 18 12 to 36 10 to 19 20 to 38 40 to 76 20 to 38 40 to 76 80 to 152 39 to 78 78 to 156 156 to 312 Modulation Rate (KHz) Fin / 128 Fin / 256 Fin / 512 Fin / 1024 General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 2 of 9 October 2003 rev 1.0 Loop Filter Selection Table VDD 3.3V P2781/82/84 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% Input MHz 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21-22 23-24 25-26 27-28 29-30 31-32 33-34 35-36 37-38 39-42 43-46 47-50 51-54 55-58 59-62 63-66 67-70 71-74 75-78 FS1 FS0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 C1 (pF) 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 C2 (pF) 330,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 1 BW = 0.75% C1 (pF) 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 C2 (pF) 330,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 1 BW = 1.00% C1 (pF) 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 270 C2 (pF) 1 BW = 1.25% C1 (pF) 560 560 560 680 330 680 270 560 560 680 470 330 330 680 390 270 270 560 560 680 470 330 330 680 390 270 270 560 560 680 470 330 330 680 390 270 270 C2 (pF) 100,000 100,000 100,000 6,800 3,300 6,800 2,700 100,000 100,000 6,800 4,700 3,300 3,300 6,800 3,900 2,700 2,700 100,000 100,000 6,800 4,700 3,300 3,300 6,800 3,900 2,700 2,700 100,000 100,000 6,800 4,700 3,300 3,300 6,800 3,900 2,700 2,700 1 R1 (ohm) 220 270 390 510 620 820 1,000 330 390 510 560 620 750 820 910 1,000 1,200 330 390 510 560 620 750 820 910 1,000 1,200 330 390 510 560 620 750 820 910 1,000 1,200 R1 (ohm) 300 390 560 750 1,000 1,200 1,500 510 560 750 820 1,000 1,100 1,200 1,300 1,500 1,600 560 620 750 820 1,000 1,100 1,200 1,300 1,500 1,600 560 620 750 820 1,000 1,100 1,200 1,300 1,600 1,800 R1 (ohm) R1 (ohm) 510 680 910 1,200 1,200 2,200 2,200 910 1,100 1,200 1,200 1,200 1,500 2,200 2,200 2,200 2,700 910 1,100 1,200 1,200 1,200 1,500 2,200 2,200 2,200 2,700 910 1,100 1,200 1,200 1,200 1,500 2,200 2,200 2,200 2,700 100,000 390 100,000 560 100,000 750 10,000 1,000 5,600 1,200 12,000 2,200 5,600 2,200 100,000 750 100,000 866(1%) 10,000 1,000 12,000 1,200 5,600 1,200 3,900 1,200 12,000 2,200 10,000 2,200 5,600 2,200 3,300 2,200 100,000 750 100,000 866 (1%) 10,000 1,000 12,000 1,200 6,800 1,200 3,900 1,200 12,000 2,200 10,000 2,200 5,600 2,200 3,300 2,200 100,000 750 100,000 866 (1%) 10,000 1,000 12,000 1,200 6,800 1,200 3,900 1,200 12,000 2,200 8,200 2,200 5,600 2,200 3,300 2,200 1 The BW value is representative of typical conditions General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 3 of 9 October 2003 rev 1.0 P2781/82/84 Spread Spectrum Selection The P278xA performs Zero Cycle Slip when set at low percentage spreading. This allows no occurrence of system timing error. The optimal setting should minimize system EMI to the fullest without affecting system performance. 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 Selection Table specifies the input frequency range. The external LF allows the user to fine tune the spread 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 VDD or VSS. Do not leave them floating. General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 4 of 9 October 2003 rev 1.0 Absolute Maximum Ratings Symbol VDD, VIN TSTG TA Parameter Voltage on any pin with respect to GND Storage temperature Operating temperature Rating -0.5 to + 7.0 -65 to +125 0 to +70 P2781/82/84 Unit V C C DC Electrical Characteristics Symbol VIL Input low voltage VIH IIL IIH IXOL IXOH VOL VOH IDD ICC VDD Input high voltage Input low current (internal input pull-up resistor on FS0 and FS1) Input high current (internal input pull-up resistor on FS0 and FS1) XOUT output low current XOUT output high current Output low voltage (VDD = 3.3 V, IOL = 20 mA) Output high voltage (VDD = 3.3 V, IOH = 20 mA) Static supply current Typical dynamic supply current (25 pF scope probe loading) Operating voltage Parameter Min GND - 0.3 2.0 - - - - - 2.5 5.2 at 3 MHz 3.0 Typ - - 60 0 10 10 - - 3 - 3.3 Max 0.8 VDD +0.3 - - - - 0.4 Unit V V A A mA mA V V mA mA V 21.2 at 82 MHz 3.6 AC Electrical Characteristics Symbol fIN fOUT tLH Parameter Input frequency: P278XX Output frequency: P2781X P2782X P2784X Min 3 3 6 12 1 1 250 1 at 3 MHz -20 0 2 at 82 MHz +20 Typ Max 78 78 156 312 Unit MHz MHz ns ns ps % % P278XX P278XX P2781X P2781X tHL tJC tD F P278XX Output rise time (measured at 0.8 V to 2.0 V, 25 pF scope probe loading) Output fall time (measured at 2.0 V to 0.8 V, 25 pF scope probe loading) Jitter (cycle to cycle, 6sigma, 1000 sweeps, 0.5% spread, I/O frequency = 16 MHz) Output duty cycle deviation (error from 50% duty cycle, 25 pF scope probe loading) Frequency deviation tolerance from BW% stated in the Loop Filter Selection Table General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 5 of 9 October 2003 rev 1.0 Package Information P2781/82/84 Mechanical Package Outline 8-Pin SOIC Symbol A A1 A2 B C D E e H L a Dimensions in inches Min 0.057 0.004 0.053 0.012 0.004 0.186 0.148 Nor 0.064 0.007 0.061 0.016 0.006 0.194 0.156 0.050 BSC 0.224 0.012 0 0.236 0.020 5 0.248 0.028 8 Max 0.071 0.010 0.069 0.020 0.01 0.202 0.164 Dimensions in millimeters Min 1.45 0.10 1.35 0.31 0.10 4.72 3.75 Nor 1.63 0.18 1.55 0.41 0.15 4.92 3.95 1.27 BSC 5.70 0.30 0 6.00 0.50 5 6.30 0.70 8 Max 1.80 0.25 1.75 0.51 0.25 5.12 4.15 Note: Controlling dimensions are millimeters SOIC - 0.074 grams unit weight General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 6 of 9 October 2003 rev 1.0 Mechanical Package Outline 8-Pin TSSOP P2781/82/84 Dimensions in inches Symbol A A1 A2 B C D E e H L a 0.244 0.018 0 0.002 0.031 0.007 0.004 0.114 0.169 0.118 0.173 0.026 BSC 0.252 0.024 0.260 0.030 8 0.039 Min Nor Max 0.047 0.006 0.041 0.012 0.008 0.122 0.177 Dimensions in millimeters Min Nor Max 1.10 0.05 0.80 0.19 0.09 2.90 4.30 3.00 4.40 0.65 BSC 6.20 0.45 0 6.40 0.60 6.60 0.75 8 1.00 0.15 1.05 0.30 0.20 3.10 4.50 5 5 Note: Controlling dimensions are millimeters TSSOP -0.034 grams unit weight General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 7 of 9 October 2003 rev 1.0 Ordering Codes Ordering Number X278XA-08ST X278XA-08SR X278XA-08TT X278XA-08TR X278XB-08TT X278XB-08TR Marking X278XA X278XA X278XA X278XA X278XB X278XB Package Type 8 PIN SOIC, TUBE 8 PIN SOIC, TAPE & REEL 8 PIN TSSOP, TUBE 8 PIN TSSOP, TAPE & REEL 8 PIN TSSOP, TUBE 8 PIN TSSOP, TAPE & REEL 2,500 2,500 2,500 QTY / Reel P2781/82/84 Temperature See flow See flow See flow See flow See flow See flow Device Ordering Information X278XX X- 08 XX Package: ST - SOIC, TUBE SR - SOIC, T/R TT - TSSOP, TUBE TR - TSSOP, T/R Pin Count F = Pb FREE DEVICE NUMBER Flow: P = Commercial Temperature Range (0C to 70C) I = Industrial Temperature Range (-25C to 85C) A = Automotive Temperature Range (-40C to 125C) General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 8 of 9 October 2003 rev 1.0 P2781/82/84 Alliance Semiconductor Corporation 2595, Augustine Drive, Santa Clara, CA 95054 Tel# 408-855-4900 Fax: 408-855-4999 www.alsc.com Copyright (c) Alliance Semiconductor All Rights Reserved Part Number: P2781/82/84 Document Version: 1.0 (c) 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 changes to this document and its products at any time without notice. Alliance assumes no responsibility for any errors that may appear in this document. The data contained herein represents Alliance's best data and/or estimates at the time of issuance. Alliance reserves 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 intended to operate as, or provide, any guarantee or warrantee to any user or customer. Alliance does not assume any responsibility or liability arising out of the application or use of any product described herein, and disclaims any express or implied warranties related to the sale and/or use of Alliance products including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any intellectual 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 patent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of Alliance or third parties. Alliance does not authorize its products for use as critical components in life-supporting systems where a malfunction or failure 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. General Purpose EMI Reduction IC Notice: The information in this document is subject to change without notice. 9 of 9 |
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