P2681A Datasheet, PDF (1/10 Pages) Alliance Semiconductor Corporation – General Purpose EMI Reduction IC

October 2003
P2681A
rev D
General Purpose EMI Reduction IC
Features
ƒ FCC approved method of EMI attenuation
ƒ Provides up to 15 dB of EMI suppression
ƒ Generates a 1 X or ½ X low EMI spread
spectrum clock of the input frequency
ƒ Output frequency from 6MHz to 20MHz
ƒ Digital spread selections
ƒ Spreading ranges from +/-0.4% to +/-5.0%
ƒ Ultra low cycle-to-cycle jitter
ƒ Zero-cycle slip
ƒ 3.3V and 5.0V operating voltage range
ƒ 10 mA output drives
ƒ TTL or CMOS compatible outputs
ƒ Ultra-low power CMOS design
ƒ Available in 8 pin SOIC and TSSOP
Product Description
The P2681A is a versatile spread spectrum
frequency modulator designed specifically for digital
camera and other digital video and imaging
applications. The P2681A reduces electromagnetic
interference (EMI) at the clock source, which
provides system wide reduction of EMI of all clock
dependent signals. The P2681A allows significant
system cost savings by reducing the number of circuit
board layers and shielding that are traditionally
required to pass EMI regulations.
The P2681A uses the most efficient and optimized
modulation profile approved by the FCC.
The P2681A 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
The P2681A is targeted towards MFP, xDSL, fax
modem, set-top box, USB controller, DSC, and
embedded systems.
Block Diagram
Alliance Semiconductor
2575, Augustine Drive • Santa Clara, CA • Tel: [phone] • Fax: [phone] • www.alsc.com
Notice: The information in this document is subject to change without notice.