View P2779AG-08TT_1292868.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

June 2005 rev 0.1 Low-Cost Notebook EMI Reduction IC
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 from 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 (-40 C to 85 C)
P2779A
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.
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
Block Diagram
PD LF VDD
Modulation XIN Crystal Oscillator XOUT Frequency Divider Feedback Divider
PLL
Phase Detector
Loop Filter
VCO
Output Divider
REF
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.
June 2005 rev 0.1
Pin Configuration
XIN/ CLKIN XOUT PD LF 1 2 3 4 8 7 6 5 VDD REF ModOUT VSS
P2779A
P2779A
Pin Description
Pin#
1 2 3 4 5 6 7 8
Pin Name
XIN / CLKIN XOUT PD LF VSS ModOUT REF VDD
Type
I O I I P O O P
Description
Connect to crystal or clock input. Crystal output. Power-down control pin. Pull low to enable power-down mode. 1 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 Loop Filter Selection Table for detail values.) Ground connection. Connect to system ground. Spread spectrum clock output. Provides a reference clock output of the input frequency. Connect to +3.3 V.
Note: 1. Connect to VDD if not used.
Loop Filter Selection Table VDD 3.3 V
Pin 4 LF C2 R1 C1
Input (MHz) 20 21-22 23-24 25-26 27-28 29-30 31-32 33-34 35-36 37-38
FS1
FS0 C1 (pF) 270 270 270 270 270 270 270 270 270 270
1 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 0
BW = 0.50% C2 R1 (pF) () 100,000 330 100,000 390 100,000 510 100,000 560 100,000 620 100,000 750 100,000 820 100,000 910 100,000 1,000 100,000 1,200
C1 (pF) 270 270 270 270 270 270 270 270 270 270
BW = 0.75% C2 R1 (pF) () 100,000 560 100,000 620 100,000 750 100,000 820 100,000 1,000 100,000 1,100 100,000 1,200 100,000 1,300 100,000 1,500 100,000 1,600
C1 (pF) 270 270 270 270 270 270 270 270 270 270
BW = 1.00% C2 R1 (pF) () 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
C1 (pF) 560 560 680 470 330 330 680 390 270 270
BW = 1.25% C2 R1 (pF) () 100,000 910 100,000 1,100 6,800 1,200 4,700 1,200 3,300 1,200 3,300 1,500 6,800 2,200 3,900 2,200 2,700 2,200 2,700 2,700
Please contact factory for loop filter values if desired spread settings are not listed.
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
2 of 8
June 2005 rev 0.1
Spread Spectrum Selection
P2779A
The P2779A performs zero cycle slip when set at low percentage spreading. This prevents any 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 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, notebook PC, and LCD monitor applications. It is optimized for operation from 20MHz to 38MHz. The P2779A's spread percentage selection is determined by the external LF value specified in the Loop Filter Selection Table. The external LF allows the user to fine tune the spread percentage to optimize the EMI reduction benefits of the spread spectrum.
Application Schematic
27 MHz
1 XIN/CLKIN VDD 8 VDD 2 XOUT 3 PD 4 LF R1 C1 REF 7 ModOUT 6 VSS 5 P2779A 0.1F +3.3V Modulated 27MHz
C2
PD selection: Power dissipation can be reduced by completely turning off the IC.
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
3 of 8
June 2005 rev 0.1
Absolute Maximum Ratings Symbol
VDD, VIN TSTG TA Ts TJ TDV Storage temperature Operating temperature Max. Soldering Temperature (10 sec) Junction Temperature Static Discharge Voltage (As per JEDEC STD22- A114-B)
P2779A
Parameter
Voltage on any pin with respect to Ground
Rating
-0.5 to +7.0 -65 to +125 0 to +70 260 150 2
Unit
V C C C C 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.
DC Electrical Characteristics Symbol
VIL VIH IIL IIH IXOL IXOH VOL VOH IDD ICC VDD tON ZOUT Input low voltage Input high voltage Input low current Input high current XOUT output low current (at 0.4 V, VDD = 3.3V) XOUT output high current (at 2.5 V, VDD = 3.3V) Output low voltage (VDD = 3.3V, IOL = 20 mA) Output high voltage (VDD = 3.3V, IOH = 20 mA) Static supply current Dynamic supply current (3.3 V, 25 pF loading, 32 MHz) Operating voltage Power-up time (first locked cycle after power up) Clock output impedance
Parameter
Min
VSS - 0.3 2.0 2.5 3.0 -
Typ
60 0 10 10 3 12 3.3 7 28
Max
0.8 VDD + 0.3 0.4 3.6 -
Unit
V V A A mA mA V V mA mA V mS
AC Electrical Characteristics Symbol
fIN fOUT tLH1 tHL
1
Parameter
Input frequency Output frequency Output rise time (measured at 0.8 V to 2.0 V) Output fall time (measured at 2.0 V to 0.8 V) Jitter (Cycle to cycle) Output duty cycle
Min
20 20 45
Typ
1 1 175 50
Max
38 38 55
Unit
MHz MHz nS nS pS %
tJC tD
Note: 1. tLH and tHL are measured into a capacitive load of 15 pF
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
4 of 8
June 2005 rev 0.1
Package Information 8-lead (150-mil) SOIC Package
P2779A
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
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
5 of 8
June 2005 rev 0.1
8-lead Thin Shrunk Small Outline Package (4.40-MM Body)
P2779A
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
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
6 of 8
June 2005 rev 0.1
Ordering Information Part number
P2779A -08ST P2779A -08SR P2779AF-08ST P2779AF-08SR P2779AG-08ST P2779AG-08SR I2779A-08ST I2779A-08SR I2779AF-08ST I2779AF-08SR I2779AG-08ST I2779AG-08SR P2779A-08TT P2779A-08TR P2779AF-08TT P2779AF-08TR P2779AG-08TT P2779AG-08TR I2779A-08TT I2779A-08TR I2779AF-08TT I2779AF-08TR I2779AG-08TT I2779AG-08TR
P2779A
Marking
P2779A P2779A P2779AF P2779AF P2779AG P2779AG I2779A I2779A I2779AF I2779AF I2779AG I2779AG P2779A P2779A P2779AF P2779AF P2779AG P2779AG I2779A I2779A I2779AF I2779AF I2779AG I2779AG
Package Configuration
8-Pin SOIC,Tube 8-Pin SOIC, Tape and Reel 8-Pin SOIC, Tube, Pb Free 8-Pin SOIC, Tape and Reel, Pb Free 8-Pin SOIC, Tube, Green 8-Pin SOIC, Tape and Reel, Green 8-Pin SOIC, Tube 8-Pin SOIC, Tape and Reel 8-Pin SOIC, Tube, Pb Free 8-Pin SOIC, Tape and Reel, Pb Free 8-Pin SOIC, Tube, Green 8-Pin SOIC, Tape and Reel, Green 8-Pin TSSOP, Tube 8-Pin TSSOP, Tape and Reel 8-Pin TSSOP, Tube, Pb Free 8-Pin TSSOP, Tape and Reel, Pb Free 8-Pin TSSOP, Tube, Green 8-Pin TSSOP, Tape and Reel, Green 8-Pin TSSOP, Tube 8-Pin TSSOP, Tape and Reel 8-Pin TSSOP, Tube, Pb Free 8-Pin TSSOP, Tape and Reel, Pb Free 8-Pin TSSOP, Tube, Green 8-Pin TSSOP, Tape and Reel, Green
Temperature Range
Commercial Commercial Commercial Commercial Commercial Commercial Industrial Industrial Industrial Industrial Industrial Industrial Commercial Commercial Commercial Commercial Commercial Commercial Industrial Industrial Industrial Industrial Industrial Industrial
Device Ordering Information
P2779A
F-08-XX
SR - SOIC, T/R TT - TSSOP, TUBE TR - TSSOP, T/R ST - SOIC, TUBE Pin Count F =Lead Free and and RoHS compliant part G = Green Deviation (%) and Spread option Identifier DEVICE NUMBER Flow: P = Commercial Temperature Range (0C to 70C) I = Industrial Temperature Range (-40C to 85C)
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
7 of 8
June 2005 rev 0.1
P2779A
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 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
(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.
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
8 of 8

▲Up To Search▲

Price & Availability of P2779AG-08TT

	To Download P2779AG-08TT Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .