ALSC I2781AG-08ST General purpose emi reduction ic Datasheet

P2781/82/84
July 2005
rev 1.5
General Purpose EMI Reduction IC
Features
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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
Zero-cycle slip
3.3V operating voltage range
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.
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 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
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.
FS0
Block Diagram
FS1
LF
VDD
PLL
Modulation
XIN /CLKIN
XOUT
Crystal
Oscillator
Frequency
Divider
Feedback
Divider
Phase
Detector
VCO
Output
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.
P2781/82/84
July 2005
rev 1.5
Pin Configuration
XIN / CLKIN
1
XOUT
2
FS1
LF
8
VDD
7
FS0
3
6
ModOUT
4
5
VSS
P278XA-08S
P278XA-08T
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.
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.
1
XIN/CLKIN
I
2
XOUT
O
3
FS1
I
4
LF
I
5
VSS
I
Ground Connection. Connect to system ground.
6
ModOUT
O
Spread Spectrum Clock Output.
7
FS0
I
Digital logic input used to select input frequency range
(see the Input Frequency Selection Table). This pin has an internal pull-up
resistor.
8
VDD
P
Connect to +3.3 V
Input Frequency Selection Table
FS1
FS0
Input (MHz)
0
0
1
1
0
1
0
1
3 to 9
10 to 19
20 to 38
39 to 78
Output Frequency Scaling (MHz)
P2781A
P2782A
P2784A
3 to 9
10 to 19
20 to 38
39 to 78
6 to 18
20 to 38
40 to 76
78 to 156
12 to 36
40 to 76
80 to 152
156 to 312
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
Modulation Rate (KHz)
Fin / 128
Fin / 256
Fin / 512
Fin / 1024
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P2781/82/84
July 2005
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.
1
1
BW = ±0.50%
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
1
BW = ±0.75%
1
BW = ±1.00%
C1
(pF)
C2
(pF)
R1
(ohm)
C1
(pF)
C2
(pF)
R1
(ohm)
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
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
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
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
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
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
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)
R1
(ohm)
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
BW = ±1.25%
C1
(pF)
C2
(pF)
R1
(ohm)
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
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
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
1 The BW value is representative of typical conditions
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
3 of 11
P2781/82/84
July 2005
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
1 XIN/CLKIN VDD 8
2 XOUT
3 FS1
C2
R1
C1
FS0 7
0.1µF
ModOUT 6
4 LF
0 Ohm
2.2 K
+3.3V
Modulated 16MHz Clock
To target Chip
VSS 5
P2781A
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
Notice: The information in this document is subject to change without notice.
4 of 11
P2781/82/84
July 2005
rev 1.5
Absolute Maximum Ratings
Symbol
VDD
Parameter
Supply voltage, DC
Rating
Unit
(VSS – 0.5) to 7
V
VI
Input voltage, DC
(VSS-0.5) to (VDD+0.5)
V
VO
Output voltage, DC
(VSS-0.5) to (VDD + 0.5)
V
IIK
Input clamp current (VI<0 or VI>VDD)
-50 to +50
mA
IOK
Output clamp current (VI<0 or VI>VDD)
-50 to +50
mA
TS
Storage temperature
-65 to +125
°C
TA
Ambient temperature range, under bias
-55 to 125
°C
TJ
Junction temperature
150
°C
Lead temperature (soldering 10 sec)
Input static discharge voltage protection
(As per JEDEC STD22- A114-B)
260
°C
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
Parameter
Min
Typ
Max
Unit
VSS – 0.3
-
0.8
V
2.0
-
VDD +0.3
V
-
60
-
µA
-
60
-
µA
-
10
-
mA
-
10
-
mA
Output low voltage (VDD = 3.3V, IOL = 20mA)
-
-
0.4
V
VOH
Output high voltage (VDD = 3.3V, IOH = 20mA)
2.5
-
-
V
IDD
Static supply current
Typical dynamic supply current
(25pF scope probe loading)
Operating voltage
-
3
-
mA
5.2 at 3MHz
-
21.2 at 82MHz
mA
3.0
3.3
3.6
V
VIL
Input low voltage
VIH
IXOL
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
IXOH
XOUT output high current
VOL
IIL
IIH
ICC
VDD
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
5 of 11
P2781/82/84
July 2005
rev 1.5
AC Electrical Characteristics
Symbol
fIN
fOUT
tLH
P278XA
tHL
P278XA
tJC
P2781A
tD
P2781A
∆F
P278XA
Parameter
Input frequency: P278XA
Output frequency:
P2781A
P2782A
P2784A
Output rise time (measured at 0.8 V to 2.0 V,
25pF scope probe loading)
Output fall time (measured at 2.0 V to 0.8 V, 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
Min
Typ
Max
Unit
3
-
78
MHz
3
6
12
-
78
156
312
MHz
-
1
-
nS
-
1
-
nS
-
±250
-
pS
±1 at 3MHz
-
±2 at 82MHz
%
-20
0
+20
%
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
6 of 11
P2781/82/84
July 2005
rev 1.5
Package Information
Mechanical Package Outline 8-Pin SOIC Package
H
E
D
A2
A
C
A1
D
θ
e
L
B
Dimensions
Symbol
Inches
Min
Max
Millimeters
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
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
7 of 11
P2781/82/84
July 2005
rev 1.5
Mechanical Package Outline 8-Pin TSSOP Package
H
E
D
A2
A
C
θ
e
A1
L
B
Dimensions
Symbol
Inches
Min
Millimeters
Max
A
Min
Max
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
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
8 of 11
P2781/82/84
July 2005
rev 1.5
Ordering Codes
Ordering #
Marking
Package Type
P278XA-08ST
P278XA
8 PIN SOIC, TUBE
P278XA-08SR
P278XA
8 PIN SOIC, TAPE & REEL
P278XA-08TT
P278XA
8 PIN TSSOP, TUBE
P278XA-08TR
P278XA
8 PIN TSSOP, TAPE & REEL
P278XAF-08ST
P278XAF
8 PIN SOIC, TUBE, Pb Free
P278XAF-08SR
P278XAF
8 PIN SOIC, TAPE AND REEL,Pb Free
P278XAF-08TT
P278XAF
8 PIN TSSOP, TUBE, Pb Free
P278XAF-08TR
P278XAF
8 PIN TSSOP, TAPE AND REEL, Pb Free
P278XAG-08ST
P278XAG
8 PIN SOIC, TUBE, Green
P278XAG-08SR
P278XAG
8 PIN SOIC, TAPE AND REEL, Green
P278XAG-08TT
P278XAG
8 PIN TSSOP, TUBE, Green
P278XAG-08TR
P278XAG
8 PIN TSSOP, TAPE AND REEL, Green
I278XA-08ST
I278XA
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
I278XAF-08ST
I278XAF
8 PIN SOIC, TUBE, Pb Free
I278XAF-08SR
I278XAF
8 PIN SOIC, TAPE AND REEL,Pb Free
I278XAF-08TT
I278XAF
8 PIN TSSOP, TUBE, Pb Free
I278XAF-08TR
I278XAF
8 PIN TSSOP, TAPE AND REEL, Pb Free
I278XAG-08ST
I278XAG
8 PIN SOIC, TUBE, Green
I278XAG-08SR
I278XAG
8 PIN SOIC, TAPE AND REEL, Green
I278XAG-08TT
I278XAG
8 PIN TSSOP, TUBE, Green
I278XAG-08TR
I278XAG
8 PIN TSSOP, TAPE AND REEL, Green
X278XA-08ST
X278XA
8 PIN SOIC, TUBE
X278XA-08SR
X278XA
8 PIN SOIC, TAPE & REEL
X278XA-08TT
X278XA
8 PIN TSSOP, TUBE
X278XA-08TR
X278XA
8 PIN TSSOP, TAPE & REEL
X278XAF-08ST
X278XAF
8 PIN SOIC, TUBE, Pb Free
X278XAF-08SR
X278XAF
8 PIN SOIC, TAPE AND REEL, Pb Free
X278XAF-08TT
X278XAF
8 PIN TSSOP, TUBE, Pb Free
X278XAF-08TR
X278XAF
8 PIN TSSOP, TAPE AND REEL, Pb Free
X278XAG-08ST
X278XAG
8 PIN SOIC, TUBE, Green
X278XAG-08SR
X278XAG
8 PIN SOIC, TAPE AND REEL, Green
X278XAG-08TT
X278XAG
8 PIN TSSOP, TUBE, Green
X278XAG-08TR
X278XAG
8 PIN TSSOP, TAPE AND REEL, Green
QTY / Reel
Temperature
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
2,500
See flow
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
See flow
See flow
2,500
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
See flow
9 of 11
P2781/82/84
July 2005
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
Notice: The information in this document is subject to change without notice.
10 of 11
P2781/82/84
July 2005
rev 1.5
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
Part Number: P2781/82/84
Document Version: 1.5
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
Notice: The information in this document is subject to change without notice.
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