A2181A-08TT Alliance Semiconductor, A2181A-08TT Datasheet

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A2181A-08TT

Manufacturer Part Number
A2181A-08TT
Description
3.3 V, 3 MHz to 78 MHz, general purpose EMI reduction IC
Manufacturer
Alliance Semiconductor
Datasheet
October 2003
rev 1.0
Features
Product Description
The P278xx is a versatile spread spectrum
frequency modulator designed specifically for digital
camera and other digital video and imaging
applications. The P278xx reduces electromagnetic
interference (EMI) at the clock source, which
provides system wide reduction of EMI of all clock
Block Diagram
2575, Augustine Drive • Santa Clara, CA • Tel: 408.855.4900 • Fax: 408.855.4999 • www.alsc.com
Provides up to 15 dB 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 78 MHz
External loop filter for spread % adjustment
Spreading ranges from ±0.25% to ±5.0%
Ultra low cycle-to-cycle jitter
3.3V operating voltage range
10 mA output drives
TTL or CMOS compatible outputs
Ultra-low power CMOS design
Available in 8 pin SOIC and TSSOP
Available for industrial and automotive
temperature ranges.
Zero-cycle slip
Notice: The information in this document is subject to change without notice.
General Purpose EMI Reduction IC
Alliance Semiconductor
dependent signals. The P278xx allows significant
system cost savings by reducing the number of
circuit
traditionally required to pass EMI regulations.
The P278xx uses the most efficient and
optimized modulation profile approved by the
FCC.
The P278xx modulates the output of a single PLL in
order to “spread” the bandwidth of a synthesized
clock and, more importantly, decreases the peak
amplitudes
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
modem, set-top box, USB controller, DSC, and
embedded systems.
The P278xx is targeted towards MFP, xDSL, fax
board
of
layers
its
harmonics.
and
shielding
P2781/82/84
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A2181A-08TT Summary of contents

Page 1

... Lowering EMI by increasing a signal’s bandwidth is called spread spectrum clock generation. Applications The P278xx is targeted towards MFP, xDSL, fax modem, set-top box, USB controller, DSC, and embedded systems. Alliance Semiconductor P2781/82/84 and shielding that are harmonics. This ...

Page 2

October 2003 rev 1.0 Pin Configuration Pin Description (P278XA) Pin# Pin Name Type XIN/CLKIN I Connect to crystal or clock input. 1 XOUT I Crystal output 2 Digital logic input used to select input frequency range (see the Input 3 ...

Page 3

October 2003 rev 1.0 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 ±0.50% Input FS1 FS0 C1 ...

Page 4

October 2003 rev 1.0 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 ...

Page 5

October 2003 rev 1.0 Absolute Maximum Ratings Symbol Parameter Voltage on any pin with respect to GND Storage temperature STG T Operating temperature A DC Electrical Characteristics Symbol Parameter V Input low voltage IL ...

Page 6

October 2003 rev 1.0 Package Information Mechanical Package Outline 8-Pin SOIC Dimensions in inches Symbol Min Nor A 0.057 0.064 A1 0.004 0.007 A2 0.053 0.061 B 0.012 0.016 C 0.004 0.006 D 0.186 0.194 E 0.148 0.156 e 0.050 ...

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October 2003 rev 1.0 Mechanical Package Outline 8-Pin TSSOP Dimensions in inches Symbol Min Nor A A1 0.002 A2 0.031 0.039 B 0.007 C 0.004 D 0.114 0.118 E 0.169 0.173 e 0.026 BSC H 0.244 0.252 L 0.018 0.024 ...

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October 2003 rev 1.0 Ordering Codes Ordering Marking Number 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 X278XB-08TT X278XB 8 ...

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... Fax: 408-855-4999 www.alsc.com © 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 ...

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