P2779A ALSC | Alldatasheet
Document overview
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Technical content
Features
Provides up to 15dB of EMI suppression FCC approved method of EMI attenuation Generates a 1X low EMI spread spectrum clock of the input frequency Operates between 20MHz and 38MHz input frequency range External loop filter for spread percentage adjustment Spreading ranges fr om ±0.25% to ±2.5% Ultra low cycle-to-cycle jitter Zero-Cycle slip at small deviations 3.3 V Operating Voltage 10 mA output drives TTL or CMOS compatible outputs Low power CMOS design Available in 8-pin SOIC and TSSOP Packages Available for Industrial temperature operating range (-40º C to 85º C) Product Description The P2779A is a versatile spread spectrum frequency modulator designed specifically for mobile and digital camera and other digital video and imaging applications. The P2779A reduces electromagnetic interference (EMI) at the clock source, which provides system-wide reduction of EMI of all clock dependent signals. The P2779A allows significant system cost savings by reducing the number of circuit board layers and shielding that are traditionally required to pass EMI regulations. The P2779A uses the most efficient and optimized modulation profile approved by the FCC. The P2779A 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 P2779A is targeted toward mobile 3D graphics chip set applications. Block Diagram VDD PD VSS ModOUT XIN Frequency Divider Feedback Divider Modulation Phase Detector Loop Filter VCO Output Divider PLL Crystal Oscillator XOUT REF LF
rev 0.1 Low-Cost Notebook EMI Reduction IC 2 of 8 Notice: The information in this document is subject to change without notice. Pin Configuration Pin Description Pin# Pin Name Type Description 1 XIN / CLKIN I Connect to crystal or clock input. 2 XOUT O Crystal output. PD I Power-down control pin. Pull low to enable power-down mode. This pin has an internal pull-up resistor.1
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 Loop Filter Selection Table for detail values.) 5 VSS P Ground connection. Connect to system ground. 6 ModOUT O Spread spectrum clock output. 7 REF O Provides a reference cl ock output of the input frequency. 8 VDD P Connect to +3.3 V. Note: 1. Connect to VDD if not used. Loop Filter Selection Table VDD 3.3 V (MHz) FS1 FS0 (pF) (pF) (Ω) (pF) (pF) (Ω) (pF) (pF) (Ω) (pF) (pF) (Ω) 20 1 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 0 270 100,000 510 270 100,0 00 750 270 10,000 1,000 680 6,800 1,200 25-26 1 0 270 100,000 560 270 100,0 00 820 270 12,000 1,200 470 4,700 1,200 27-28 1 0 270 100,000 620 270 100,0 00 1,000 270 6,800 1, 200 330 3,300 1,200 29-30 1 0 270 100,000 750 270 100,0 00 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 1,000 270 100,0 00 1,500 270 5,600 2, 200 270 2,700 2,200 37-38 1 0 270 100,000 1,200 270 100,0 00 1,600 270 3,300 2, 200 270 2,700 2,700 Please contact factory for loop filter values if desired spread settings are not listed. C2 C1 Pin 4 LF REF VSS 4 5 P2779A XIN/ CLKIN XOUT PD LF VDD ModOUT
rev 0.1 Low-Cost Notebook EMI Reduction IC 3 of 8 Notice: The information in this document is subject to change without notice. Spread Spectrum Selection The P2779A performs zero cycle slip when set at low percentag e spreading. This prevents any occurrence of system timing error. The optimal setting should minimize system EMI to the fullest without affect ing system performance. The spreading is described as a percentage deviation of the center frequency. (Note that the center frequency is the frequency of the external reference input on XIN/CLKIN, pin 1.) The P2779A is designed for PC peripheral, networking, noteb ook PC, and LCD monitor applications. It is optimized for operation from 20MHz to 38MHz. The P 2779A’s spread percentage selection is determined by the external LF value specified in the Loop Filter Selection Tabl e. The external LF allows the user to fine tune the spread percentage to optimize the EMI reduction benefits of the spread spectrum. Application Schematic PD selection: Power dissipation can be reduced by completely turning off the IC. VDD REF ModOUT VSSLF PD XOUT XIN/CLKIN P2779A +3.3V Modulated 27MHz
27 MHz
0.1µF VDD
rev 0.1 Low-Cost Notebook EMI Reduction IC 4 of 8 Notice: The information in this document is subject to change without notice. Absolute Maximum Ratings Symbol Parameter Rating Unit VDD, VIN Voltage on any pin with respect to Ground -0.5 to +7.0 V TSTG Storage temperature -65 to +125 °C TA Operating temperature 0 to +70 °C Ts Max. Soldering Temperature (10 sec) 260 °C TJ Junction Temperature 150 °C TDV Static Discharge Voltage (As per JEDEC STD22- A114-B) 2 KV 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. Symbol Parameter Min Typ Max Unit VIL Input low voltage VSS - 0.3 - 0.8 V VIH Input high voltage 2.0 - VDD + 0.3 V IIL Input low current - 60 - µA IIH Input high current - 0 - µA IXOL XOUT output low current (at 0.4 V, V DD = 3.3V) - 10 - mA IXOH XOUT output high current (at 2.5 V, V DD = 3.3V) - 10 - mA VOL Output low voltage (V DD = 3.3V, IOL = 20 mA) - - 0.4 V VOH Output high voltage (V DD = 3.3V, IOH = 20 mA) 2.5 - - V IDD Static supply current - 3 - mA ICC Dynamic supply current (3.3 V, 25 pF loading, 32 MHz) - 12 - mA VDD Operating volta ge 3.0 3.3 3.6 V tON Power-up time (first locked cycle after power up) - 7 - mS ZOUT Clock output impedance - 28 - Ω Symbol Parameter Min Typ Max Unit fIN Input frequency 20 - 38 MHz fOUT Output frequency 20 - 38 MHz tLH 1 Output rise time (measured at 0.8 V to 2.0 V) - 1 - nS tHL 1 Output fall time (measured at 2.0 V to 0.8 V) - 1 - nS tJC Jitter (Cycle to cycle) - ±175 - pS tD Output duty cycle 45 50 55 % Note: 1. tLH and tHL are measured into a capacitive load of 15 pF
rev 0.1 Low-Cost Notebook EMI Reduction IC 5 of 8 Notice: The information in this document is subject to change without notice.
Package Information
8-lead (150-mil) SOIC Package D E H D A2 A θ L C B e Dimensions Inches Millimeters Symbol Min Max Min Max A1 0.004 0.010 0.10 0.25 A 0.053 0.069 1.35 1.75 A2 0.049 0.059 1.25 1.50 B 0.012 0.020 0.31 0.51 C 0.007 0.010 0.18 0.25 D 0.193 BSC 4.90 BSC E 0.154 BSC 3.91 BSC e 0.050 BSC 1.27 BSC H 0.236 BSC 6.00 BSC L 0.016 0.050 0.41 1.27 θ 0° 8° 0° 8° Note: Controlling dimensions are millimeters SOIC – 0.074 grams unit weight
rev 0.1 Low-Cost Notebook EMI Reduction IC 6 of 8 Notice: The information in this document is subject to change without notice. E H A D B C L θ e 8-lead Thin Shrunk Small Outline Package (4.40-MM Body) Dimensions Inches Millimeters Symbol Min Max Min Max A 0.043 1.10 A1 0.002 0.006 0.05 0.15 A2 0.033 0.037 0.85 0.95 B 0.008 0.012 0.19 0.30 c 0.004 0.008 0.09 0.20 D 0.114 0.122 2.90 3.10 E 0.169 0.177 4.30 4.50 e 0.026 BSC 0.65 BSC H 0.252 BSC 6.40 BSC L 0.020 0.028 0.50 0.70 θ 0° 8° 0° 8° Note: Controlling dimensions are millimeters TSSOP – 0.0325 grams unit weight
rev 0.1 Low-Cost Notebook EMI Reduction IC 7 of 8 Notice: The information in this document is subject to change without notice.
Ordering Information
Part number Marking Package Configuration Temperature Range P2779A -08ST P2779A 8-Pin SOIC,Tube Commercial P2779A -08SR P2779A 8-Pin SOIC, Tape and Reel Commercial P2779AF-08ST P2779AF 8-Pin SOIC, Tube, Pb Free Commercial P2779AF-08SR P2779AF 8-Pin SOIC, Tape and Reel, Pb Free Commercial P2779AG-08ST P2779AG 8-Pin SOIC, Tube, Green Commercial P2779AG-08SR P2779AG 8-Pin SOIC, Tape and Reel, Green Commercial I2779A-08ST I2779A 8-Pin SOIC, Tube Industrial I2779A-08SR I2779A 8-Pin SOIC, Tape and Reel Industrial I2779AF-08ST I2779AF 8-Pin SOIC, Tube, Pb Free Industrial I2779AF-08SR I2779AF 8-Pin SOIC, Tape and Reel, Pb Free Industrial I2779AG-08ST I2779AG 8-Pin SOIC, Tube, Green Industrial I2779AG-08SR I2779AG 8-Pin SOIC, Tape and Reel, Green Industrial P2779A-08TT P2779A 8-Pin TSSOP, Tube Commercial P2779A-08TR P2779A 8-Pin TSSOP, Tape and Reel Commercial P2779AF-08TT P2779AF 8-Pin TSSOP, Tube, Pb Free Commercial P2779AF-08TR P2779AF 8-Pin TSSOP, Tape and Reel, Pb Free Commercial P2779AG-08TT P2779AG 8-Pin TSSOP, Tube, Green Commercial P2779AG-08TR P2779AG 8-Pin TSSOP, Tape and Reel, Green Commercial I2779A-08TT I2779A 8-Pin TSSOP, Tube Industrial I2779A-08TR I2779A 8-Pin TSSOP, Tape and Reel Industrial I2779AF-08TT I2779AF 8-Pin TSSOP, Tube, Pb Free Industrial I2779AF-08TR I2779AF 8-Pin TSSOP, Tape and Reel, Pb Free Industrial I2779AG-08TT I2779AG 8-Pin TSSO P, Tube, Green Industrial I2779AG-08TR I2779AG 8-Pin TSSOP, Tape and Reel, Green Industrial Device Ordering Information P2779A F-08-XX SR - SOIC, T/R TT – TSSOP, TUBE TR - TSSOP, T/R ST – SOIC, TUBE DEVICE NUMBER Flow: P = Commercial Temperature Range (0°C to 70°C) I = Industrial Temperature Range (-40°C to 85°C) Pin Count Deviation (%) and Spread option Identifier F =Lead Free and and RoHS compliant part G = Green Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
rev 0.1 Low-Cost Notebook EMI Reduction IC 8 of 8 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 2575, Augustine Drive, Santa Clara, CA 95054 Tel# 408-855-4900 Fax: 408-855-4999 www.alsc.com Copyright © Alliance Semiconductor All Rights Reserved Preliminary Information Part Number: P2779A Document Version: v0.1 Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003