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November 2003 rev 1.1
ASM3P2185A
EMI Reduction IC
Features
FCC approved method of EMI attenuation. Provides up to 15dB EMI reduction. Generates a 1X low EMI spread spectrum clock of the input frequency. Input frequency range: 25MHz to 50 MHz. Internal loop filter minimizes external components and board space. Down Spread and Center Spread. 2 spread frequency deviation selections: -1.25% and 0.6%. Low inherent cycle-to-cycle jitter. 3.3V operating voltage range. TTL or CMOS compatible inputs and outputs. Low power CMOS design. Supports notebook VGA and other LCD timing controller applications. Products are available for industrial temperature range. Available in 8-pin SOIC and TSSOP. The ASM3P2185A reduces electromagnetic interference (EMI) at the clock source, allowing system wide EMI reduction for all the down stream clocks and data dependent signals. The ASM3P2185A 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 ASM3P2185A uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method. The ASM3P2185A 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'.
Product Description
The ASM3P2185A is a versatile spread spectrum frequency modulator designed specifically for a wide range of input clock frequencies from 25MHz to 50MHz. The ASM3P2185A can generate an EMI reduced clock from an OSC or a system generated clock.
Applications
The ASM3P2185A 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.
Block Diagram
SS%
VDD
Modulation XIN Crystal Oscillator XOUT Feedback Divider Frequenc y Phase Detector Loop Filter
PLL
VCO
Output Divider ModOUT
VSS
Alliance Semiconductor 2575, Augustine Drive * Santa Clara, CA * Tel: 408.855.4900 * Fax: 408.855.4999 * www.alsc.com
Notice: The information in this document is subject to change without notice.
November 2003 rev 1.1
Pin Configuration
XIN XOUT GND SS%
1 2 8 7
ASM3P2185A
NC NC VDD ModOUT
ASM3P2185A
3 6 5
4
Pin Description Pin# 1 2 3 4 5 6 7 8 Pin Name XIN XOUT GND SS% ModOUT VDD NC NC Type I I P I O P Description Crystal connection or external reference frequency input. This pin has dual functions. It can be connected to either an external crystal or an external reference clock. Crystal connection. Input connection for an external crystal. If using an external reference, this pin must be left unconnected. Ground to entire chip. Spread range select. Digital logic input used to select frequency deviation (Refer Spread Deviation Table). This pin has an internal pull-up resistor. Spread spectrum low EMI output. Power supply for the entire chip (3.3V). No Connect. No Connect.
Spread Deviation Selection Table SS% (pin 4) 0 1 Spread Deviation (%) - 1.25 0.6%
EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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November 2003 rev 1.1
ASM3P2185A
Absolute Maximum Ratings Symbol VDD, VIN TSTG TA Parameter Voltage on any pin with respect to GND Storage temperature Rating -0.5 to + 7.0 -65 to +125 Unit V C
Operating temperature 0 to 70 C Note: These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for extended periods may affect device reliability.
DC Electrical Characteristics Symbol VIL VIH IIL IIH IXOL IXOH VOL VOH ICC IDD VDD tON ZOUT Input low voltage Input high voltage Input low current Input high current XOUT Output low current (@ 0.4V, VDD = 3.3V) XOUT Output high current (@ 2.5V, VDD = 3.3V) Output low voltage (VDD = 3.3V, IOL = 20mA) Output high voltage (VDD = 3.3V, IOH = 20mA) Dynamic supply current Normal mode (3.3V and 10pF loading) Static supply current Standby mode Operating voltage Power up time (first locked clock cycle after power up) Clock out impedance Parameter Min GND - 0.3 2.0 2.5 8.46 Typ TBD TBD 12 0.6 2.7 3.3 0.18 50 3.7 Max 0.8 VDD + 0.3 -35 35 0.4 17.78 Unit V V A A mA mA V V mA mA V mS
EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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November 2003 rev 1.1
AC Electrical Characteristics Symbol XIN ModOUT tLH* tHL* tJC TD Input frequency Output frequency Output rise time (measured at 0.8V to 2.0V) Output fall time (measured at 2.0V to 0.8V) Jitter (cycle to cycle) Output duty cycle Parameter Min 25 25 1.2 0.8 45
ASM3P2185A
Typ 1.32 0.9 50
Max 50 50 1.4 1.0 360 55
Unit MHz MHz ns ns ps %
tLH and tHL are measured into a capacitive load of 15pF
EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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November 2003 rev 1.1
Package Information
ASM3P2185A
8-Pin SOIC
E
H
D
A2
A
e B A 1
C L
Symbol Dimensions in inches Min A A1 A2 B C D E e H L 0.057 0.004 0.053 0.012 0.004 0.186 0.148 Max 0.071 0.010 0.069 0.020 0.01 0.202 0.164
Dimensions in millimeters Min 1.45 0.10 1.35 0.31 0.10 4.72 3.75 Max 1.80 0.25 1.75 0.51 0.25 5.12 4.15 1.27 BSC 5.70 0.30 0 6.30 0.70 8
0.050 BSC 0.224 0.012 0 0.248 0.028 8
D
EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
November 2003 rev 1.1
ASM3P2185A
8-Pin TSSOP
H
E D A2 A e B A1 L C
Dimensions in inches Symbol A A1 A2 B C D E e H L Min 0.047 0.002 0.031 0.007 0.004 0.114 0.169 0.006 0.041 0.012 0.008 0.122 0.177 Max
Dimensions in millimeters Min Max 1.10 0.05 0.80 0.19 0.09 2.90 4.30 0.65 BSC 6.20 0.45 0 6.60 0.75 8 0.15 1.05 0.30 0.20 3.10 4.50
0.026 BSC 0.244 0.018 0 0.260 0.030 8
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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November 2003 rev 1.1
ASM3P2185A
Alliance Semiconductor Corporation 2575, Augustine Drive, Santa Clara, CA 95054 Tel# 408-855-4900 Fax: 408-855-4999 www.alsc.com
Copyright (c) Alliance Semiconductor All Rights Reserved Preliminary Information Part Number: ASM3P2185A Document Version: v1.1
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003
(c) Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our name and Intelliwatt are trademarks or registered trademarks of Alliance. All other brand and product names may be the trademarks of their respective companies. Alliance reserves the right to make changes to this document and its products at any time without notice. Alliance assumes no responsibility for any errors that may appear in this document. The data contained herein represents Alliance's best data and/or estimates at the time of issuance. Alliance reserves the right to change or correct this data at any time, without notice. If the product described herein is under development, significant changes to these specifications are possible. The information in this product data sheet is intended to be general descriptive information for potential customers and users, and is not intended to operate as, or provide, any guarantee or warrantee to any user or customer. Alliance does not assume any responsibility or liability arising out of the application or use of any product described herein, and disclaims any express or implied warranties related to the sale and/or use of Alliance products including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any intellectual property rights, except as express agreed to in Alliance's Terms and Conditions of Sale (which are available from Alliance). All sales of Alliance products are made exclusively according to Alliance's Terms and Conditions of Sale. The purchase of products from Alliance does not convey a license under any patent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of Alliance or third parties. Alliance does not authorize its products for use as critical components in life-supporting systems where a malfunction or failure may reasonably be expected to result in significant injury to the user, and the inclusion of Alliance products in such life-supporting systems implies that the manufacturer assumes all risk of such use and agrees to indemnify Alliance against all claims arising from such use.
EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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