ALSC I2779A-08SR Low-cost notebook emi reduction ic Datasheet

P2779A
June 2005
rev 0.1
Low-Cost Notebook EMI Reduction IC
Features
the clock source, which provides system-wide reduction of
ƒ
Provides up to 15dB of EMI suppression
EMI of all clock dependent signals. The P2779A allows
ƒ
FCC approved method of EMI attenuation
significant system cost savings by reducing the number of
ƒ
Generates a 1X low EMI spread spectrum clock of
circuit board layers and shielding that are traditionally
the input frequency
required to pass EMI regulations.
Operates between 20MHz and 38MHz input
The P2779A uses the most efficient and optimized
frequency range
modulation profile approved by the FCC.
ƒ
External loop filter for spread percentage adjustment
The P2779A modulates the output of a single PLL in order
ƒ
Spreading ranges from ±0.25% to ±2.5%
to spread the bandwidth of a synthesized clock and, more
ƒ
Ultra low cycle-to-cycle jitter
importantly,
ƒ
Zero-Cycle slip at small deviations
harmonics. This results in significantly lower system EMI
ƒ
3.3 V Operating Voltage
compared to the typical narrow-band signal produced by
ƒ
10 mA output drives
oscillators and most frequency generators. Lowering EMI
ƒ
TTL or CMOS compatible outputs
by increasing a signal’s bandwidth is called spread
ƒ
Low power CMOS design
spectrum clock generation.
ƒ
Available in 8-pin SOIC and TSSOP Packages
ƒ
Available for Industrial temperature operating
ƒ
decreases
the
peak
amplitudes
of
its
Applications
range (-40º C to 85º C)
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
VDD
LF
PLL
Modulation
XIN
Crystal
Oscillator
XOUT
Frequency
Divider
Feedback
Divider
Phase
Detector
Loop
Filter
VCO
Output
Divider
ModOUT
REF
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.
P2779A
June 2005
rev 0.1
Pin Configuration
8
VDD
7
REF
3
6
ModOUT
4
5
VSS
XIN/ CLKIN
1
XOUT
2
PD
LF
P2779A
Pin Description
Pin#
Pin Name
Type
1
XIN / CLKIN
I
Connect to crystal or clock input.
2
XOUT
O
Crystal output.
3
I
PD
Description
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.)
4
LF
I
5
VSS
P
Ground connection. Connect to system ground.
6
ModOUT
O
Spread spectrum clock output.
7
REF
O
Provides a reference clock 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
Pin 4 LF
C2
R1
C1
Input
(MHz)
FS1
20
21-22
23-24
25-26
27-28
29-30
31-32
33-34
35-36
37-38
1
1
1
1
1
1
1
1
1
1
FS0
0
0
0
0
0
0
0
0
0
0
C1
(pF)
270
270
270
270
270
270
270
270
270
270
BW = ± 0.50%
C2
R1
(pF)
(Ω)
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)
(Ω)
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)
(Ω)
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)
(Ω)
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
P2779A
June 2005
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
1 XIN/CLKIN VDD 8
VDD
2 XOUT
3 PD
REF 7
C2
+3.3V
ModOUT 6
4 LF
R1
C1
0.1µF
Modulated 27MHz
VSS 5
P2779A
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
P2779A
June 2005
rev 0.1
Absolute Maximum Ratings
Symbol
Parameter
VDD, VIN
Voltage on any pin with respect to Ground
-0.5 to +7.0
V
Storage temperature
-65 to +125
°C
0 to +70
°C
TSTG
Rating
Unit
TA
Operating temperature
Ts
Max. Soldering Temperature (10 sec)
260
°C
TJ
Junction Temperature
150
°C
2
KV
TDV
Static Discharge Voltage
(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
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, VDD = 3.3V)
-
10
-
mA
IXOH
XOUT output high current (at 2.5 V, VDD = 3.3V)
-
10
-
mA
VOL
Output low voltage (VDD = 3.3V, IOL = 20 mA)
-
-
0.4
V
VOH
Output high voltage (VDD = 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 voltage
3.0
3.3
3.6
V
tON
Power-up time (first locked cycle after power up)
-
7
-
mS
Clock output impedance
-
28
-
Ω
ZOUT
AC Electrical Characteristics
Symbol
Min
Typ
Max
Unit
Input frequency
20
-
38
MHz
fOUT
Output frequency
20
-
38
MHz
tLH1
Output rise time (measured at 0.8 V to 2.0 V)
-
1
-
nS
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
%
fIN
tHL
1
Parameter
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
P2779A
June 2005
rev 0.1
Package Information
8-lead (150-mil) 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
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
5 of 8
P2779A
June 2005
rev 0.1
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
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
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
6 of 8
P2779A
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
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
Temperature Range
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
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
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
Notice: The information in this document is subject to change without notice.
7 of 8
P2779A
June 2005
rev 0.1
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
© 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
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components in life-supporting systems where a malfunction or failure may reasonably be expected to result in significant
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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
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