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P2779AG-08TT [ALSC]

Low-Cost Notebook EMI Reduction IC; 低价笔记本EMI降低IC
P2779AG-08TT
型号： P2779AG-08TT
厂家： ALLIANCE SEMICONDUCTOR CORPORATION    ALLIANCE SEMICONDUCTOR CORPORATION
描述：

Low-Cost Notebook EMI Reduction IC
低价笔记本EMI降低IC

晶体 时钟发生器 微控制器和处理器 外围集成电路 光电二极管 ISM频段
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中文：  中文翻译
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June 2005  
rev 0.1  
P2779A  
Low-Cost Notebook EMI Reduction IC  
Features  
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.  
ƒ
ƒ
ƒ
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  
ƒ
Operates between 20MHz and 38MHz input  
frequency range  
The P2779A uses the most efficient and optimized  
modulation profile approved by the FCC.  
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
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  
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.  
Available in 8-pin SOIC and TSSOP Packages  
Available for Industrial temperature operating  
range (-40º C to 85º C)  
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  
VDD  
PD  
LF  
PLL  
Modulation  
XIN  
XOUT  
REF  
Frequency  
Divider  
Crystal  
Oscillator  
Output  
Loop  
Filter  
Phase  
VCO  
Divider  
Detector  
Feedback  
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.  
June 2005  
P2779A  
rev 0.1  
Pin Configuration  
VDD  
1
2
3
4
8
7
6
5
XIN/ CLKIN  
XOUT  
REF  
P2779A  
ModOUT  
VSS  
PD  
LF  
Pin Description  
Pin#  
Pin Name  
Type  
Description  
1
2
XIN / CLKIN  
XOUT  
I
Connect to crystal or clock input.  
Crystal output.  
O
I
Power-down control pin. Pull low to enable power-down mode.  
3
4
PD  
LF  
This pin has an internal pull-up resistor.1  
External loop filter for the PLL. By changing the value of the CRC circuit,  
the percentage spread can be adjusted accordingly.  
I
(See Loop Filter Selection Table for detail values.)  
5
6
7
8
VSS  
ModOUT  
REF  
P
O
O
P
Ground connection. Connect to system ground.  
Spread spectrum clock output.  
Provides a reference clock output of the input frequency.  
Connect to +3.3 V.  
VDD  
Note: 1. Connect to VDD if not used.  
Loop Filter Selection Table VDD 3.3 V  
Pin 4 LF  
R1  
C2  
C1  
Input FS1 FS0  
(MHz)  
BW = ± 0.50%  
BW = ± 0.75%  
BW = ± 1.00%  
BW = ± 1.25%  
C1  
C2  
R1  
(Ω)  
C1  
C2  
R1  
C1  
C2  
R1  
C1  
C2  
R1  
(pF)  
(pF)  
(pF)  
(pF)  
(Ω)  
(pF)  
(pF)  
(Ω)  
(pF)  
(pF)  
(Ω)  
20  
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
270 100,000  
270 100,000  
270 100,000  
270 100,000  
270 100,000  
270 100,000  
270 100,000  
270 100,000  
330  
390  
510  
560  
620  
750  
820  
910  
270 100,000 560  
270 100,000 620  
270 100,000 750  
270 100,000 820  
270 100,000 750  
560 100,000  
910  
21-22  
23-24  
25-26  
27-28  
29-30  
31-32  
33-34  
35-36  
37-38  
270 100,000 866(1%) 560 100,000  
1,100  
1,200  
1,200  
1,200  
1,500  
2,200  
2,200  
2,200  
2,700  
270 10,000  
270 12,000  
1,000  
1,200  
1,200  
1,200  
2,200  
2,200  
2,200  
2,200  
680 6,800  
470 4,700  
330 3,300  
330 3,300  
680 6,800  
390 3,900  
270 2,700  
270 2,700  
270 100,000 1,000 270 6,800  
270 100,000 1,100 270 3,900  
270 100,000 1,200 270 12,000  
270 100,000 1,300 270 10,000  
270 100,000 1,000 270 100,000 1,500 270 5,600  
270 100,000 1,200 270 100,000 1,600 270 3,300  
Please contact factory for loop filter values if desired spread settings are not listed.  
Low-Cost Notebook EMI Reduction IC  
2 of 8  
Notice: The information in this document is subject to change without notice.  
June 2005  
P2779A  
rev 0.1  
Spread Spectrum Selection  
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  
XIN/CLKIN VDD  
1
2
3
4
8
7
6
5
0.1µF  
XOUT  
PD  
REF  
ModOUT  
VSS  
VDD  
+3.3V  
Modulated 27MHz  
LF  
R1  
C1  
P2779A  
C2  
PD selection: Power dissipation can be reduced by completely turning off the IC.  
Low-Cost Notebook EMI Reduction IC  
3 of 8  
Notice: The information in this document is subject to change without notice.  
June 2005  
P2779A  
rev 0.1  
Absolute Maximum Ratings  
Symbol  
Parameter  
Voltage on any pin with respect to Ground  
Rating  
-0.5 to +7.0  
-65 to +125  
0 to +70  
260  
Unit  
V
°C  
°C  
°C  
°C  
VDD, VIN  
TSTG  
TA  
Storage temperature  
Operating temperature  
Ts  
TJ  
Max. Soldering Temperature (10 sec)  
Junction Temperature  
150  
Static Discharge Voltage  
TDV  
2
KV  
(As per JEDEC STD22- A114-B)  
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  
Parameter  
Min  
Typ  
Max  
Unit  
VIL  
Input low voltage  
VSS - 0.3  
-
0.8  
V
VIH  
IIL  
IIH  
Input high voltage  
Input low current  
Input high current  
2.0  
-
-
-
60  
0
VDD + 0.3  
V
µA  
µA  
-
-
IXOL  
IXOH  
VOL  
VOH  
IDD  
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  
-
-
10  
10  
-
-
-
mA  
mA  
V
-
0.4  
-
2.5  
-
-
V
3
-
mA  
Dynamic supply current  
ICC  
-
12  
-
mA  
(3.3 V, 25 pF loading, 32 MHz)  
VDD  
tON  
Operating voltage  
3.0  
3.3  
7
3.6  
V
mS  
Ω
Power-up time (first locked cycle after power up)  
Clock output impedance  
-
-
-
-
ZOUT  
28  
AC Electrical Characteristics  
Symbol  
Parameter  
Min  
Typ  
-
-
1
1
±175  
50  
Max  
Unit  
fIN  
Input frequency  
20  
20  
-
-
-
38  
38  
-
-
-
MHz  
MHz  
nS  
nS  
pS  
fOUT  
Output frequency  
1
tLH  
tHL  
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)  
1
tJC  
tD  
Output duty cycle  
45  
55  
%
Note: 1. tLH and tHL are measured into a capacitive load of 15 pF  
Low-Cost Notebook EMI Reduction IC  
4 of 8  
Notice: The information in this document is subject to change without notice.  
June 2005  
P2779A  
rev 0.1  
Package Information  
8-lead (150-mil) SOIC Package  
H
E
D
A2  
A
C
θ
e
A1  
L
B
Dimensions  
Symbol  
Inches  
Millimeters  
Min  
Max  
0.010  
0.069  
0.059  
0.020  
0.010  
Min  
0.10  
1.35  
1.25  
0.31  
0.18  
Max  
0.25  
1.75  
1.50  
0.51  
0.25  
A1  
A
0.004  
0.053  
0.049  
0.012  
0.007  
A2  
B
C
D
E
0.193 BSC  
0.154 BSC  
0.050 BSC  
0.236 BSC  
4.90 BSC  
3.91 BSC  
1.27 BSC  
6.00 BSC  
e
H
L
0.016  
0°  
0.050  
8°  
0.41  
0°  
1.27  
8°  
θ
Note: Controlling dimensions are millimeters  
SOIC – 0.074 grams unit weight  
Low-Cost Notebook EMI Reduction IC  
5 of 8  
Notice: The information in this document is subject to change without notice.  
June 2005  
rev 0.1  
P2779A  
8-lead Thin Shrunk Small Outline Package (4.40-MM Body)  
H
E
D
A2  
A
C
θ
e
A1  
L
B
Dimensions  
Symbol  
Inches  
Millimeters  
Min  
Max  
Min  
Max  
A
A1  
A2  
B
0.043  
0.006  
0.037  
0.012  
0.008  
0.122  
0.177  
1.10  
0.002  
0.033  
0.008  
0.004  
0.114  
0.169  
0.05  
0.85  
0.19  
0.09  
2.90  
4.30  
0.15  
0.95  
0.30  
0.20  
3.10  
4.50  
c
D
E
e
0.026 BSC  
0.252 BSC  
0.65 BSC  
6.40 BSC  
H
L
0.020  
0°  
0.028  
8°  
0.50  
0°  
0.70  
8°  
θ
Note: Controlling dimensions are millimeters  
TSSOP – 0.0325 grams unit weight  
Low-Cost Notebook EMI Reduction IC  
6 of 8  
Notice: The information in this document is subject to change without notice.  
June 2005  
P2779A  
rev 0.1  
Ordering Information  
Part number  
P2779A -08ST  
P2779A -08SR  
P2779AF-08ST  
P2779AF-08SR  
P2779AG-08ST  
P2779AG-08SR  
I2779A-08ST  
Marking  
Package Configuration  
Temperature Range  
Commercial  
Commercial  
Commercial  
Commercial  
Commercial  
Commercial  
Industrial  
P2779A  
8-Pin SOIC,Tube  
P2779A  
P2779AF  
P2779AF  
P2779AG  
P2779AG  
I2779A  
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  
I2779A-08SR  
I2779A  
8-Pin SOIC, Tape and Reel  
8-Pin SOIC, Tube, Pb Free  
Industrial  
I2779AF-08ST  
I2779AF-08SR  
I2779AG-08ST  
I2779AG-08SR  
P2779A-08TT  
P2779A-08TR  
P2779AF-08TT  
P2779AF-08TR  
P2779AG-08TT  
P2779AG-08TR  
I2779A-08TT  
I2779AF  
I2779AF  
I2779AG  
I2779AG  
P2779A  
P2779A  
P2779AF  
P2779AF  
P2779AG  
P2779AG  
I2779A  
Industrial  
8-Pin SOIC, Tape and Reel, Pb Free  
8-Pin SOIC, Tube, Green  
Industrial  
Industrial  
8-Pin SOIC, Tape and Reel, Green  
8-Pin TSSOP, Tube  
Industrial  
Commercial  
Commercial  
Commercial  
Commercial  
Commercial  
Commercial  
Industrial  
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  
I2779A-08TR  
I2779A  
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  
Industrial  
I2779AF-08TT  
I2779AF-08TR  
I2779AG-08TT  
I2779AG-08TR  
I2779AF  
I2779AF  
I2779AG  
I2779AG  
Industrial  
Industrial  
Industrial  
Industrial  
Device Ordering Information  
P 2 7 7 9 A F - 0 8 - X X  
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 (0°C to 70°C)  
I = Industrial Temperature Range (-40°C to 85°C)  
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.  
Low-Cost Notebook EMI Reduction IC  
7 of 8  
Notice: The information in this document is subject to change without notice.  
June 2005  
rev 0.1  
P2779A  
Alliance Semiconductor Corporation  
2575, Augustine Drive,  
Santa Clara, CA 95054  
Tel# 408-855-4900  
Copyright © Alliance Semiconductor  
All Rights Reserved  
Preliminary Information  
Part Number: P2779A  
Document Version: v0.1  
Fax: 408-855-4999  
www.alsc.com  
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003  
© 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  
8 of 8  
Notice: The information in this document is subject to change without notice.  

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