ASM3P2811A Datasheet, PDF (1/9 Pages) Alliance Semiconductor Corporation – Low Power EMI Reduction IC

ASM3P2811A/B,
ASM3P2812A/B,
ASM3P2814A/B
Low Power EMI Reduction IC
Description
The ASM3P28XX devices are versatile spread spectrum frequency
modulators designed specifically for a wide range of input clock
frequencies from 10 MHz to 40 MHz. Refer to Input/Output
Frequency Range Selection Table. The ASM3P28XX can generate an
EMI reduced clock from crystal, ceramic resonator, or system clock.
The ASM3P28XX−A and the ASM3P28XX−B offer various
combinations of spread options and percentage deviations. Refer to
Frequency Deviation and Spread Selection Table. These combinations
include Down and Center Spread, and percentage deviation range
from ±0.625% to −3.5%.
The ASM3P28XX reduces electromagnetic interference (EMI) at
the clock source, allowing system wide reduction of EMI of down
stream clock and data dependent signals. The ASM3P28XX 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 ASM3P28XX 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.’
The ASM3P28XX uses the most efficient and optimized
modulation profile approved by the FCC and is implemented in a
proprietary all−digital method.
http://onsemi.com
SOIC−8
S SUFFIX
CASE 751BD
TSSOP−8
T SUFFIX
CASE 948AL
PIN CONFIGURATION
1
XIN / CLKIN
XOUT
VSS
VDD
D_C
FRS
SRS
ModOUT
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 7 of this data sheet.
Applications
The ASM3P28XX is targeted towards EMI management for memory and LVDS interfaces in mobile graphic chipsets and
high−speed digital applications such as PC peripheral devices, consumer electronics, and embedded controller systems.
Features
• FCC Approved Method of EMI Attenuation
• Provides up to 15 dB EMI Reduction
• Generates a 1x, 2x and 4x Low EMI Spread Spectrum
Clock of the Input Frequency
♦ 1x: ASM3P2811A/B
♦ 2x: ASM3P2812A/B
♦ 4x: ASM3P2814A/B
• Optimized for Input Frequency Range from 10 MHz to
40 MHz
• Internal Loop Filter Minimizes External Components
and Board Space
• Selectable Spread Options:
♦ Down Spread and Center Spread
• 8 Frequency Deviation Selections:
♦ ±0.625% to −3.5%
• Low Inherent Cycle−to−Cycle Jitter
• 3.3 V Operating Voltage
• CMOS/TTL Compatible Inputs and Outputs
• Pin−out Compatible with Cypress CY25811, CY25812
and CY25814
• Commercial and Industrial Temperature Range
• Available in 8−pin SOIC and TSSOP Packages
• These Devices are Pb−Free, Halogen Free/BFR Free
and are RoHS Compliant
© Semiconductor Components Industries, LLC, 2011
1
August, 2011 − Rev. 3
Publication Order Number:
ASM3P2811A/D