ASM3P2111B
Peak EMI Reducing Solution
©2010 SCILLC. All rights reserved. Publication Order Number:
JANUARY 2010 – Rev. 1 ASM3P2111/D
Features
• Generates an EMI optimized clock at the output.
• Input frequency: 25MHz.
• Frequency outputs:
o 60MHz (unmodulated)
o 2 x 48MHz (unmodulated)
o 66.6MHz (modulated): -1.7% down spread
• Modulation rate: 30KHz.
• Supply voltage range: 3.3V ± 0.3V.
• Available in 8-pin SOIC Package.
• RoHS Compliant
Product Description
The ASM3P2111B is a versatile spread spectrum
frequency modulator that reduces electromagnetic
interference (EMI) at the clock source. The ASM3P2111B
allows significant system cost savings by reducing the
number of circuit board layers and shielding that are
required to pass EMI regulations. The ASM3P2111B
modulates the output of 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.
Applications
ASM3P2111B is targeted towards EMI management for
high speed digital applications such as PC peripheral
devices, consumer electronics and embedded controller
systems.
Block Diagram
Crystal
Oscillator
66.6MHz
Modulated
XIN / CLKIN
XOUT
V
SS
48MHz_2
60MHz
48MHz_1
PLL1
PLL2 48MHz_1
V
DD
