ASM3P2180A Datasheet, PDF (1/6 Pages) Alliance Semiconductor Corporation – Peak Reducing EMI Solution

ASM3P2180A
Peak Reducing EMI Solution
Features
• Generates a 1x EMI optimized clock output.
• Input frequency: 6MHz - 10MHz
18MHz - 30MHz
• Output frequency: 6MHz - 10MHz
18MHz - 30MHz
• Two selectable down spread options.
• Selectable frequency range.
• Integrated loop filter components.
• Operates with a 3.3V supply.
• CMOS design.
• 8-pin SOIC packages.
Product Description
The ASM3P2180A is a versatile spread spectrum
frequency modulator designed specifically for a wide
range of clock frequencies. ASM3P2180A reduces
electromagnetic interference (EMI) at the clock source,
allowing system wide reduction of EMI of down stream
clock and data dependent signals. ASM3P2180A allows
Block Diagram
significant system cost savings by reducing the number
of circuit board layers, and shielding that are traditionally
required to pass EMI regulations. ASM3P2180A
modulates the output of a single PLL in order to
“spread” the bandwidth of a synthesized clock, thereby
decreasing 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 clock generators. Lowering EMI by increasing
a signal’s bandwidth is called spread spectrum clock
generation. ASM3P2180A uses the most efficient and
optimized modulation profile approved by the FCC and
is implemented by using a proprietary all-digital method.
Applications
The ASM3P2180A is targeted towards notebook LCD
displays, other displays using an LVDS interface, PC
peripheral devices and embedded systems.
VDD
SS%
FS
CLKIN / XIN
XOUT
Crystal
Oscillator
Modulation
PLL
CLKOUT
GND
©2010 SCILLC. All rights reserved.
JANUARY 2010 – Rev. 2
Publication Order Number:
ASM3P2180/D