P2005A Datasheet, PDF (1/10 Pages) Alliance Semiconductor Corporation – Low Frequency EMI Reduction IC

October 2003
P2005A/S
rev 1.0
Low Frequency EMI Reduction IC
Features
FCC approved method of EMI attenuation.
Provides up to 15dB of EMI suppression.
Generates a 1X or ½ X low EMI spread spectrum
clock of the input frequency.
Input frequency range: 8MHz to 32MHz.
Internal loop filter minimizes external components
and board space.
Frequency deviation:
o P2005A: ± 1% to ± 3%
o P2005S: ± 0.6% to ± 1.8%
SSON# control pin for spread spectrum enable
and disable options.
Low cycle-to-cycle jitter.
3.3V or 5V operating voltage range.
16mA output drives.
TTL or CMOS compatible outputs.
Ultra-low power CMOS design.
Available in 8-pin SOIC and TSSOP.
Product Description
The P2005X is a versatile spread spectrum frequency
modulator designed specifically for input clock
frequencies from 8MHz to 32MHz. Refer Output
Frequency Selection Table. The P2005X can generate an
EMI reduced clock from crystal, ceramic resonator, or
system clock. The P2005X offers various percentage
deviations ranging form ±0.6% to ±3.0%. Refer
Frequency Deviation Selections Table. The P2005X
reduces electromagnetic interference (EMI) at the clock
source, allowing system wide reduction of EMI of down
stream clock and data dependent signals. The P2005X
allows significant system cost savings by reducing the
number of circuit board layers ferrite beads, shielding
and other passive components that are traditionally
required to pass EMI regulations.
The P2005X uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
The P2005X 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 P2005X is targeted towards EMI management for
high-speed digital applications such as PC peripheral
devices, consumer electronics and embedded controller
systems.
Block Diagram
SR0 SSON#
VDD
DIV2
XIN
XOUT
Crystal
Oscillator
Frequency
Divider
Feedback
Divider
Modulation
Phase
Detector
Loop
Filter
PLL
VCO
Output
Divider
MODOUT
VSS
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.