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P2781/82/84 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 * Ultra-low power CMOS design * P278xA is available in an 8 pin SOIC Package 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 result 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.
Product Description
The P278xA is a versatile spread spectrum frequency modulator designed specifically for digital camera and other digital video and imaging applications. The P278xA reduces electromagnetic interference (EMI) at the clock
Applications
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
(c)2010 SCILLC. All rights reserved. JANUARY 2010 - Rev. 2
Publication Order Number: P2781/82/84
P2781/82/84
Pin Configuration
XIN / CLKIN XOUT FS1 LF
1 2
8 VDD 7 FS0
P278xA
3 4 6 ModOUT 5
VSS
Standard pin Configuration offered in both 8 pin SOIC 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
3 to 9 10 to 19 20 to 38 39 to 78
P2782A
6 to 18 20 to 38 40 to 76 78 to 156
P2784A
12 to 36 40 to 76 80 to 152 156 to 312
Modulation Rate (KHz)
Fin / 128 Fin / 256 Fin / 512 Fin / 1024
Rev. 2 | Page 2 of 8 | www.onsemi.com
P2781/82/84
Loop Filter Selection Table VDD 3.3V
Contact PulseCore for loop values that are not listed in the table and for component selection values for industrial and automotive temperatures.
BW = 0.50%1 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 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
BW = 0.75%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 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 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
BW = 1.00%1 C2 (pF) R1 (ohm) 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
BW = 1.25%1 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 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
Note: 1. The BW value is representative of typical conditions.
Rev. 2 | Page 3 of 8 | www.onsemi.com
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 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.
+3.3V 16 MHz 1 XIN/CLKIN VDD 8 2.2 K 2 XOUT 3 FS1 R1 C1 4 LF 0 Ohm FS0 7 ModOUT 6 VSS 5 P278xA Modulated 16MHz Clock To target Chip 0.1F
C2
Note: Both logic input pins FS1 and FS0 have to be connected to either VDD or VSS. Do not leave them floating.
Rev. 2 | Page 4 of 8 | www.onsemi.com
P2781/82/84
Absolute Maximum Ratings Symbol
VDD, VIN TSTG Ts TJ TDV Storage temperature Max. Soldering Temperature (10 sec) Junction Temperature Static Discharge Voltage (As per JEDEC STD22- A114-B)
Parameter
Rating
-0.5 to +4.6 -65 to +125 260 150 2
Unit
V C C C KV
Voltage on any pin with respect to Ground
Note: These are stress ratings only and are not implied for functional use. Exposure to absolute maximum ratings for prolonged periods of time may affect device reliability.
Operating Conditions Parameter
VDD TA CL CIN Supply Voltage Operating Temperature (Ambient Temperature) Load Capacitance Input Capacitance
Description
Min
3.0 -40
Max
3.6 +85 15 7
Unit
V C pF pF
DC Electrical Characteristics
(Test condition: All parameters are measured at room temperature (+25 unless otherwise stated.) C)
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
Typ
Max
0.8 VDD +0.3
Unit
V V A A mA mA
60 60 10 10 0.4 2.5 3 5.2 at 3MHz 3.0 3.3 21.2 at 82MHz 3.6
V V mA mA V
Rev. 2 | Page 5 of 8 | www.onsemi.com
P2781/82/84
AC Electrical Characteristics Symbol
fIN
Parameter
Min
3
Typ
Max
78 78 156 312
Unit
Input frequency: P278xA P2781A
3 6 12 1 1 250 1 @ 3MHz -20 0
MHz
fOUT
Output frequency:
P2782A P2784A
tLH tHL tJC tD F
P278xA P278xA P2781A P2781A P278xA
Output rise time (measured at 0.8V to 2.0V, 25pF scope probe loading) Output fall time (measured at 2.0V to 0.8V, 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
nS nS pS 2 @ 82MHz +20 % %
Rev. 2 | Page 6 of 8 | www.onsemi.com
P2781/82/84
Package Information 8-Pin SOIC Package
E
H
D
A2
A
e A 1 B
C L
D
Dimensions Inches Min
A1 A A2 B C D E e H L 0.004 0.053 0.049 0.012 0.007
Symbol
Millimeters Max Min
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
Max
0.25 1.75 1.50 0.51 0.25
0.010 0.069 0.059 0.020 0.010
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.
Rev. 2 | Page 7 of 8 | www.onsemi.com
P2781/82/84
Ordering Codes Ordering #
P2781AF-08ST P2781AF-08SR I2781AF-08ST I2781AG-08SR P2782AF-08SR P2784AF-08SR
Top Marking
ABG ABG ABH ABJ ABK ABO
Package Type
8 PIN SOIC, TUBE, Pb Free 8 PIN SOIC, TAPE AND REEL,Pb Free 8 PIN SOIC, TUBE, Pb Free 8 PIN SOIC, TAPE AND REEL, Green 8 PIN SOIC, TAPE AND REEL,Pb Free 8 PIN SOIC, TAPE AND REEL,Pb Free
Temperature
0 to + 70 C C 0 to +70 C C 0 to + 70 C C 0 to +70 C C 0 to +70 C C 0 to +70 C C
A "microdot" placed at the end of last row of marking or just below the last row toward the center of package indicates Pb-free.
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
Note: This product utilizes US Patent #6,646,463 Impedance Emulator Patent issued to PulseCore Semiconductor, dated 11-11-2003. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. U.S Patent Pending; Timing-Safe and Active Bead are trademarks of PulseCore Semiconductor, a wholly owned subsidiary of ON Semiconductor. This literature is subject to all applicable copyright laws and is not for resale in any manner.
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