X2782AG-08TT [ALSC]
General Purpose EMI Reduction IC; 通用EMI降低IC
| 型号： | X2782AG-08TT |
| 厂家： | 
ALLIANCE SEMICONDUCTOR CORPORATION |
| 描述： | General Purpose EMI Reduction IC |
| 文件： | 总11页 (文件大小：170K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
July 2005
rev 1.5
P2781/82/84
General Purpose EMI Reduction IC
Features
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.
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
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”
Zero-cycle slip
the bandwidth of
a synthesized clock and, more
3.3V operating voltage range
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.
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.
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.
LF
VDD
FS1
FS0
Block Diagram
PLL
Modulation
XIN /CLKIN
Frequency
Crystal
Divider
Output
Divider
Oscillator
XOUT
Phase
Detector
VCO
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.
July 2005
P2781/82/84
rev 1.5
Pin Configuration
XIN / CLKIN
XOUT
FS1
VDD
1
2
3
4
8
7
6
5
FS0
P278XA-08S
P278XA-08T
ModOUT
VSS
LF
Standard pin Configuration offered in both
8 pin SOIC and TSSOP Packages
Pin Description (P278XA)
Pin#
Pin Name
Type
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.
1
XIN/CLKIN
I
2
3
XOUT
FS1
O
I
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.
4
LF
I
5
6
VSS
I
Ground Connection. Connect to system ground.
Spread Spectrum Clock Output.
ModOUT
O
Digital logic input used to select input frequency range
(see the Input Frequency Selection Table). This pin has an internal pull-up
resistor.
7
8
FS0
I
VDD
P
Connect to +3.3 V
Input Frequency Selection Table
Output Frequency Scaling (MHz)
Modulation Rate (KHz)
FS1
FS0
Input (MHz)
P2781A
3 to 9
P2782A
6 to 18
P2784A
12 to 36
0
0
1
1
0
1
0
1
3 to 9
Fin / 128
Fin / 256
Fin / 512
Fin / 1024
10 to 19
20 to 38
39 to 78
10 to 19
20 to 38
39 to 78
20 to 38
40 to 76
78 to 156
40 to 76
80 to 152
156 to 312
General Purpose EMI Reduction IC
2 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
Loop Filter Selection Table VDD 3.3V
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%1
C2
BW = ±0.75%1
C2
BW = ±1.00%1
C2
BW = ±1.25%1
C2 R1
Input
MHz
FS1 FS0
C1
(pF)
R1
C1
R1
C1
R1
C1
(pF)
(pF)
(ohm) (pF)
(pF)
(ohm) (pF)
(pF)
(ohm)
(pF)
(ohm)
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
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
270 330,000 220
270 100,000 270
270 100,000 390
270 100,000 510
270 100,000 620
270 100,000 820
270 330,000 300
270 100,000 390
270 100,000 560
270 100,000 750
270 100,000 1,000 270
270 100,000 1,200 270
270 100,000
270 100,000
270 100,000
390
560
750
1,000
1,200
2,200
2,200
750
560
560
560
680
330
680
270
560
100,000
100,000
100,000
6,800
3,300
6,800
510
680
910
270
10,000
5,600
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
12,000
5,600
270 100,000
270 100,000 1,000 270 100,000 1,500 270
2,700
270 100,000 330
270 100,000 390
270 100,000 510
270 100,000 560
270 100,000 620
270 100,000 750
270 100,000 820
270 100,000 910
270 100,000 510
270 100,000 560
270 100,000 750
270 100,000 820
270 100,000 1,000 270
270 100,000 1,100 270
270 100,000 1,200 270
270 100,000 1,300 270
100,000
100,000
6,800
4,700
3,300
3,300
6,800
3,900
2,700
270 100,000 866(1%) 560
270
270
10,000
12,000
5,600
1,000
1,200
1,200
1,200
2,200
2,200
2,200
2,200
750
680
470
330
330
680
390
270
270
560
3,900
12,000
10,000
5,600
270 100,000 1,000 270 100,000 1,500 270
270 100,000 1,200 270 100,000 1,600 270
19
20
3,300
270 100,000
270 100,000 866 (1%) 560
2,700
270 100,000 330
270 100,000 390
270 100,000 510
270 100,000 560
270 100,000 620
270 100,000 750
270 100,000 820
270 100,000 910
270 100,000 560
270 100,000 620
270 100,000 750
270 100,000 820
270 100,000 1,000 270
270 100,000 1,100 270
270 100,000 1,200 270
270 100,000 1,300 270
100,000
100,000
6,800
4,700
3,300
3,300
6,800
3,900
2,700
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
270
270
10,000
12,000
6,800
1,000
1,200
1,200
1,200
2,200
2,200
2,200
2,200
750
680
470
330
330
680
390
270
270
560
3,900
12,000
10,000
5,600
270 100,000 1,000 270 100,000 1,500 270
270 100,000 1,200 270 100,000 1,600 270
3,300
270 100,000
270 100,000 866 (1%) 560
2,700
270 100,000 330
270 100,000 390
270 100,000 510
270 100,000 560
270 100,000 620
270 100,000 750
270 100,000 820
270 100,000 910
270 100,000 560
270 100,000 620
270 100,000 750
270 100,000 820
270 100,000 1,000 270
270 100,000 1,100 270
270 100,000 1,200 270
270 100,000 1,300 270
100,000
100,000
6,800
4,700
3,300
3,300
6,800
3,900
2,700
270
270
10,000
12,000
6,800
3,900
12,000
8,200
5,600
3,300
1,000
1,200
1,200
1,200
2,200
2,200
2,200
2,200
680
470
330
330
680
390
270
270
270 100,000 1,000 270 100,000 1,600 270
270 100,000 1,200 270 100,000 1,800 270
2,700
1 The BW value is representative of typical conditions
General Purpose EMI Reduction IC
3 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
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.
16 MHz
XIN/CLKIN VDD
1
2
3
4
8
7
6
5
0.1µF
+3.3V
2.2 K
XOUT
FS0
FS1
Modulated 16MHz Clock
To target Chip
ModOUT
LF
VSS
R1
C1
P2781A
0 Ohm
C2
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
4 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
Absolute Maximum Ratings
Symbol
VDD
VI
Parameter
Rating
(VSS – 0.5) to 7
(VSS-0.5) to (VDD+0.5)
(VSS-0.5) to (VDD + 0.5)
-50 to +50
Unit
V
Supply voltage, DC
Input voltage, DC
V
VO
Output voltage, DC
V
IIK
Input clamp current (VI<0 or VI>VDD)
Output clamp current (VI<0 or VI>VDD)
Storage temperature
mA
mA
°C
°C
°C
°C
IOK
-50 to +50
TS
-65 to +125
TA
Ambient temperature range, under bias
Junction temperature
-55 to 125
TJ
150
Lead temperature (soldering 10 sec)
260
Input static discharge voltage protection
(As per JEDEC STD22- A114-B)
2
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 (+25°C) unless otherwise stated)
Symbol
VIL
Parameter
Min
VSS – 0.3
2.0
Typ
Max
0.8
Unit
V
Input low voltage
-
-
VIH
Input high voltage
Input low current
VDD +0.3
V
IIL
-
-
60
60
-
-
µA
µA
(internal input pull-up resistor on FS0 and FS1)
Input high current
IIH
(internal input pull-up resistor on FS0 and FS1)
IXOL
IXOH
XOUT output low current
XOUT output high current
-
-
10
10
-
-
mA
mA
VOL
VOH
Output low voltage (VDD = 3.3V, IOL = 20mA)
-
-
-
0.4
V
Output high voltage (VDD = 3.3V, IOH = 20mA)
Static supply current
2.5
-
-
V
IDD
-
3
-
mA
Typical dynamic supply current
(25pF scope probe loading)
ICC
5.2 at 3MHz
3.0
21.2 at 82MHz mA
3.6
VDD
Operating voltage
3.3
V
General Purpose EMI Reduction IC
5 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
AC Electrical Characteristics
Symbol
Parameter
Min
Typ
Max
Unit
fIN
Input frequency: P278XA
3
-
78
MHz
P2781A
P2782A
P2784A
3
6
12
78
156
312
fOUT
Output frequency:
-
MHz
tLH
Output rise time (measured at 0.8 V to 2.0 V,
-
1
-
nS
nS
pS
%
P278XA 25pF scope probe loading)
tHL
Output fall time (measured at 2.0 V to 0.8 V, 25
-
1
-
P278XA pF scope probe loading)
tJC
Jitter (cycle to cycle, ± 6sigma, 1000 sweeps,
-
±250
-
P2781A ± 0.5% spread, I/O frequency = 16MHz)
tD
Output duty cycle deviation (error from 50% duty
±1 at 3MHz
-20
-
±2 at 82MHz
+20
P2781A cycle, 25pF scope probe loading)
∆F
Frequency deviation tolerance from BW% stated
0
%
P278XA in the Loop Filter Selection Table
General Purpose EMI Reduction IC
6 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
Package Information
Mechanical Package Outline 8-Pin 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
General Purpose EMI Reduction IC
7 of 11
Notice: The information in this document is subject to change without notice.
July 2005
rev 1.5
P2781/82/84
Mechanical Package Outline 8-Pin TSSOP Package
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
General Purpose EMI Reduction IC
8 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
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
Marking
P278XA
P278XA
P278XA
P278XA
P278XAF
P278XAF
P278XAF
P278XAF
P278XAG
P278XAG
P278XAG
P278XAG
I278XA
Package Type
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
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
I278XA-08SR
I278XA
8 PIN SOIC, TAPE & REEL
I278XA-08TT
I278XA
8 PIN TSSOP, TUBE
I278XA-08TR
I278XA
8 PIN TSSOP, TAPE & REEL
8 PIN SOIC, TUBE, Pb Free
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
I278XAF
I278XAF
I278XAF
I278XAF
I278XAG
I278XAG
I278XAG
I278XAG
X278XA
X278XA
X278XA
X278XA
X278XAF
X278XAF
X278XAF
X278XAF
X278XAG
X278XAG
X278XAG
X278XAG
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
General Purpose EMI Reduction IC
9 of 11
Notice: The information in this document is subject to change without notice.
July 2005
P2781/82/84
rev 1.5
Device Ordering Information
P 2 7 8 X A
F - 0 8 X X
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 (0°C to 70°C)
I = Industrial Temperature Range (-40°C to 85°C)
X = Automotive Temperature Range (-40°C to 125°C)
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920
General Purpose EMI Reduction IC
10 of 11
Notice: The information in this document is subject to change without notice.
July 2005
rev 1.5
P2781/82/84
Copyright © Alliance Semiconductor
All Rights Reserved
Part Number: P2781/82/84
Document Version: 1.5
Alliance Semiconductor Corporation
2575, Augustine Drive,
Santa Clara, CA 95054
Tel# 408-855-4900
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.
General Purpose EMI Reduction IC
11 of 11
Notice: The information in this document is subject to change without notice.
相关型号：
X2783AF-08SR
Clock Generator, CMOS, PDSO8, ROHS COMPLIANT, SOIC-8Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
PULSECORE
X2783AF-08TT
Clock Generator, CMOS, PDSO8, ROHS COMPLIANT, TSSOP-8Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
PULSECORE
X2783AG-08SR
Clock Generator, CMOS, PDSO8, GREEN, SOIC-8Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
PULSECORE
X2783AG-08ST
Clock Generator, CMOS, PDSO8, GREEN, SOIC-8Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
PULSECORE
X2783AG-08TR
Clock Generator, CMOS, PDSO8, GREEN, TSSOP-8Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
PULSECORE
X2784A-08SR
General Purpose EMI Reduction ICWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
ALSC
X2784A-08ST
General Purpose EMI Reduction ICWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
ALSC
X2784A-08TR
General Purpose EMI Reduction ICWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
ALSC
X2784A-08TR
Clock Generator, 312MHz, CMOS, PDSO8, TSSOP-8Warning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
PULSECORE
X2784A-08TT
General Purpose EMI Reduction ICWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
ALSC
X2784AF-08SR
General Purpose EMI Reduction ICWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
ALSC
X2784AF-08ST
General Purpose EMI Reduction ICWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
ALSC
©2020 ICPDF网 联系我们和版权申明