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July 2005 rev 1.5 General Purpose EMI Reduction IC
Features
Provides up to 15dB 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 78MHz 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 P278XA is available in 8 pin SOIC and TSSOP Packages Available for industrial and automotive temperature ranges.
P2781/82/84
other digital video and imaging applications. The P278xA reduces electromagnetic interference (EMI) at the clock source, which provides system wide reduction of EMI of all clock dependent signals. The P278xA allows significant system cost savings by reducing the number of circuit board layers and shielding that are traditionally required to pass EMI regulations. The P278xA uses the most efficient and optimized modulation profile approved by the FCC. The P278xA 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 Product Description
The P278xA is a versatile spread spectrum frequency modulator designed specifically for digital camera and The P278xA is targeted towards MFP, xDSL, fax modem, set-top box, USB controller, DSC, and embedded systems.
Block Diagram
FS0
FS1
LF
VDD
PLL Modulation XIN /CLKIN XOUT Crystal Oscillator Frequency Divider Feedback Divider Phase Detector VCO
Output Divider
ModOUT
VSS
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.
July 2005 rev 1.5
Pin Configuration
XIN / CLKIN XOUT FS1 LF 1 2 3 4
P278XA-08S P278XA-08T
P2781/82/84
8 7 6 5
VDD FS0 ModOUT VSS
Standard pin Configuration offered in both 8 pin SOIC and TSSOP Packages
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 O I I I O I P
Description
Connect to crystal or clock input. This pin has dual functions. It can be connected either to an external crystal or an external reference clock. Crystal connection. If using an external reference, this pin must be left unconnected. 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) P2781A P2782A P2784A
3 to 9 10 to 19 20 to 38 39 to 78 6 to 18 20 to 38 40 to 76 78 to 156 12 to 36 40 to 76 80 to 152 156 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.
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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.
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Spread Spectrum Selection
P2781/82/84
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 78MHz 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.
16 MHz
1 XIN/CLKIN VDD 8 2 XOUT 3 FS1 FS0 7 ModOUT 6 VSS 5 P2781A 2.2 K 0.1F +3.3V Modulated 16MHz Clock To target Chip
C2
R1 C1
4 LF 0 Ohm
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.
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July 2005 rev 1.5
Absolute Maximum Ratings Symbol
VDD VI VO IIK IOK TS TA TJ Input voltage, DC Output voltage, DC Input clamp current (VI<0 or VI>VDD) Output clamp current (VI<0 or VI>VDD) Storage temperature Ambient temperature range, under bias Junction temperature Lead temperature (soldering 10 sec) Input static discharge voltage protection (As per JEDEC STD22- A114-B)
P2781/82/84
Parameter
Supply voltage, DC
Rating
(VSS - 0.5) to 7 (VSS-0.5) to (VDD+0.5) (VSS-0.5) to (VDD + 0.5) -50 to +50 -50 to +50 -65 to +125 -55 to 125 150 260 2
Unit
V V V mA mA C C C C kV
Note: These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for extended periods may affect device reliability.
DC Electrical Characteristics
(Test condition: All parameters are measured at room temperature (+25C) unless otherwise stated)
Symbol
VIL VIH IIL IIH IXOL IXOH VOL VOH IDD ICC VDD Input low voltage
Parameter
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 = 3.3V, IOL = 20mA) Output high voltage (VDD = 3.3V, IOH = 20mA) Static supply current Typical dynamic supply current (25pF scope probe loading) Operating voltage
Min
VSS - 0.3 2.0 2.5 5.2 at 3MHz 3.0
Typ
60 60 10 10 3 3.3
Max
0.8 VDD +0.3 0.4 21.2 at 82MHz 3.6
Unit
V V A A mA mA V V mA mA V
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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AC Electrical Characteristics Symbol
fIN fOUT tLH P278XA tHL P278XA tJC P2781A tD P2781A F P278XA
P2781/82/84
Parameter
Input frequency: P278XA Output frequency: P2781A P2782A P2784A
Min
3 3 6 12 1 at 3MHz -20
Typ
-
Max
78 78 156 312 2 at 82MHz +20
Unit
MHz MHz
Output rise time (measured at 0.8 V to 2.0 V, 25pF 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 = 16MHz) Output duty cycle deviation (error from 50% duty cycle, 25pF scope probe loading) Frequency deviation tolerance from BW% stated in the Loop Filter Selection Table
1 1 250 0
nS nS pS % %
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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Package Information Mechanical Package Outline 8-Pin SOIC Package
P2781/82/84
E
H
D
A2
A
e B A 1
C L
D
Dimensions
Symbol Min
A1 A A2 B C D E e H L
Inches Max
0.010 0.069 0.059 0.020 0.010 0.004 0.053 0.049 0.012 0.007
Millimeters Min Max
0.10 1.35 1.25 0.31 0.18 4.90 BSC 3.91 BSC 1.27 BSC 6.00 BSC 0.41 0 1.27 8 0.25 1.75 1.50 0.51 0.25
0.193 BSC 0.154 BSC 0.050 BSC 0.236 BSC 0.016 0 0.050 8
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.
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Mechanical Package Outline 8-Pin TSSOP Package
P2781/82/84
H
E D A2 A e B A1 L C
Dimensions Symbol Min
A A1 A2 B c D E e H L 0.020 0 0.002 0.033 0.008 0.004 0.114 0.169 0.026 BSC 0.252 BSC 0.028 8 0.50 0
Inches Max
0.043 0.006 0.037 0.012 0.008 0.122 0.177 0.05 0.85 0.19 0.09 2.90 4.30
Millimeters Min Max
1.10 0.15 0.95 0.30 0.20 3.10 4.50 0.65 BSC 6.40 BSC 0.70 8
Note: Controlling dimensions are millimeters TSSOP - 0.0325 grams unit weight
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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Ordering Codes Ordering #
P278XA-08ST P278XA-08SR P278XA-08TT P278XA-08TR P278XAF-08ST P278XAF-08SR P278XAF-08TT P278XAF-08TR P278XAG-08ST P278XAG-08SR P278XAG-08TT P278XAG-08TR I278XA-08ST I278XA-08SR I278XA-08TT I278XA-08TR I278XAF-08ST I278XAF-08SR I278XAF-08TT I278XAF-08TR I278XAG-08ST I278XAG-08SR I278XAG-08TT I278XAG-08TR X278XA-08ST X278XA-08SR X278XA-08TT X278XA-08TR X278XAF-08ST X278XAF-08SR X278XAF-08TT X278XAF-08TR X278XAG-08ST X278XAG-08SR X278XAG-08TT X278XAG-08TR
P2781/82/84
Marking
P278XA P278XA P278XA P278XA P278XAF P278XAF P278XAF P278XAF P278XAG P278XAG P278XAG P278XAG I278XA I278XA I278XA I278XA I278XAF I278XAF I278XAF I278XAF I278XAG I278XAG I278XAG I278XAG X278XA X278XA X278XA X278XA X278XAF X278XAF X278XAF X278XAF X278XAG X278XAG X278XAG X278XAG
Package Type
8 PIN SOIC, TUBE 8 PIN SOIC, TAPE & REEL 8 PIN TSSOP, TUBE 8 PIN TSSOP, TAPE & REEL 8 PIN SOIC, TUBE, Pb Free 8 PIN SOIC, TAPE AND REEL,Pb Free 8 PIN TSSOP, TUBE, Pb Free 8 PIN TSSOP, TAPE AND REEL, Pb Free 8 PIN SOIC, TUBE, Green 8 PIN SOIC, TAPE AND REEL, Green 8 PIN TSSOP, TUBE, Green 8 PIN TSSOP, TAPE AND REEL, Green 8 PIN SOIC, TUBE 8 PIN SOIC, TAPE & REEL 8 PIN TSSOP, TUBE 8 PIN TSSOP, TAPE & REEL 8 PIN SOIC, TUBE, Pb Free 8 PIN SOIC, TAPE AND REEL,Pb Free 8 PIN TSSOP, TUBE, Pb Free 8 PIN TSSOP, TAPE AND REEL, Pb Free 8 PIN SOIC, TUBE, Green 8 PIN SOIC, TAPE AND REEL, Green 8 PIN TSSOP, TUBE, Green 8 PIN TSSOP, TAPE AND REEL, Green 8 PIN SOIC, TUBE 8 PIN SOIC, TAPE & REEL 8 PIN TSSOP, TUBE 8 PIN TSSOP, TAPE & REEL 8 PIN SOIC, TUBE, Pb Free 8 PIN SOIC, TAPE AND REEL, Pb Free 8 PIN TSSOP, TUBE, Pb Free 8 PIN TSSOP, TAPE AND REEL, Pb Free 8 PIN SOIC, TUBE, Green 8 PIN SOIC, TAPE AND REEL, Green 8 PIN TSSOP, TUBE, Green 8 PIN TSSOP, TAPE AND REEL, Green
QTY / Reel
2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500
Temperature
See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow See flow
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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Device Ordering Information
P2781/82/84
P278XA
F-
08 XX
Package: ST - SOIC, TUBE SR - SOIC, T/R TT - TSSOP, TUBE TR - TSSOP, T/R
Pin Count
F = LEAD FREE or RoHS COMPLIANT PART G = GREEN
DEVICE NUMBER
Flow: P = Commercial Temperature Range (0C to 70C) I = Industrial Temperature Range (-40C to 85C) X = Automotive Temperature Range (-40C to 125C)
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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P2781/82/84
Alliance Semiconductor Corporation 2575, 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: 1.5
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003
(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.
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