I2779AF 查看數據表（PDF） - PulseCore Semiconductor
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I2779AF Datasheet PDF : 8 Pages
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February 2007
rev 0.2
Low-Cost Notebook EMI Reduction IC
P2779A
Features
• Provides up to 15dB of EMI suppression
• FCC approved method of EMI attenuation
• Generates a 1X low EMI spread spectrum clock of
the input frequency
• Operates between 20MHz and 38MHz input
frequency range
• External loop filter for spread percentage
adjustment
• Spreading ranges from ±0.25% to ±2.5%
• Ultra low cycle-to-cycle jitter
• Zero-Cycle slip at small deviations
• 3.3 V Operating Voltage
• Low power CMOS design
• Available in 8-pin SOIC and TSSOP Packages
• Available in Industrial temperature operating
range (-40º C to 85º C)
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
the clock source, which provides system-wide reduction of
EMI of all clock dependent signals. The P2779A allows
significant system cost savings by reducing the number of
circuit board layers and shielding that are traditionally
required to pass EMI regulations.
The P2779A uses the most efficient and optimized
modulation profile approved by the FCC.
The P2779A 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 P2779A is targeted toward mobile 3D graphics chip set
applications.
LF
VDD
XIN
XOUT
Crystal
Oscillator
REF
Frequency
Divider
Feedback
Divider
Modulation
Phase
Detector
Loop
Filter
PLL
VCO
Output
Divider
ModOUT
VSS
PulseCore Semiconductor Corporation
1715 S. Bascom Ave Suite 200, Campbell, CA 95008 • Tel: 408-879-9077 • Fax: 408-879-9018
www.pulsecoresemi.com
Notice: The information in this document is subject to change without notice.
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