ASM3P2669A Datasheet, PDF (1/7 Pages) Alliance Semiconductor Corporation – Low Power Peak EMI Reducing Solution

ASM3P2669A
Peak EMI
Reducing Solution
Features
• Generates a 1X low EMI spread spectrum clock of
the input frequency.
• Integrated loop filter components.
• Operates with a 3.3V / 2.5V supply.
• Operating current less than 4mA.
• CMOS design.
• Input frequency range: 6MHz to 12MHz for 2.5V
6MHz to 13MHz for 3.3V
• Frequency deviation: ±1% @ 10MHz
• 6L-TSOP (6L-TSOT-23)
Product Description
The ASM3P2669A is a versatile spread spectrum
frequency modulator designed specifically for a wide
range of clock frequencies. The ASM3P2669A reduces
electromagnetic interference (EMI) at the clock source,
allowing system wide reduction of EMI of all clock
dependent signals. The ASM3P2669A allows significant
Block Diagram
VDD
PD
CLKIN
Frequency
Divider
Feedback
Divider
Modulation
Phase
Detector
system cost savings by reducing the number of circuit
board layers, ferrite beads and shielding that are
traditionally required to pass EMI regulations.
The ASM3P2669A uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented by using a proprietary all digital method.
The ASM3P2669A 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.’
Application
The ASM3P2669A is targeted towards all portable
devices like MP3 players and digital still cameras.
Loop
Filter
PLL
VCO
Output
Divider
ModOUT
VSS
©2010 SCILLC. All rights reserved.
JANUARY 2010 – Rev. 2
Publication Order Number:
ASM3P2669/D