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October 2003 rev 1.0
ASM3P2821B
Features
FCC approved method of EMI attenuation. Generates a 1X low EMI spread spectrum clock of the input frequency. Input frequency range: 15MHz - 27MHz. Internal loop filter minimizes external components and board space. Frequency deviation: -2.5% Low inherent cycle-to-cycle jitter. 3.3V operating voltage. TTL or CMOS compatible inputs and outputs. Ultra-low power CMOS design. o Pinout range. Available in 8-pin SOIC and TSSOP. TBD mA @ 3.3V, 24MHz compatible with Cypress CY25811.
The ASM3P2821B reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of down stream clock and data dependent signals. The ASM3P2821B 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 ASM3P2821B uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method. The ASM3P2821B 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'.
Products are available for industrial temperature
Product Description
The ASM3P2821B is a versatile spread spectrum frequency modulator designed specifically for input clock frequencies in the range of 15MHz - 27MHz. The ASM3P2821B can generate an EMI reduced clock from a ceramic resonator or system clock. The ASM3P2821B offers a percentage deviation of -2.5%.
Applications
The ASM3P2821B is targeted towards EMI management for high speed digital applications such as PC peripheral devices, consumer electronics and embedded controller systems.
Block Diagram
VDD
Modulation XIN Crystal Oscillator
PLL
Frequency Divider Feedback Divider
Phase Detector
Loop Filter
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.
ASM3P2821B
Pin Configuration
XIN VSS NC
1 8
NC VDD NC ModOUT
2
7
ASM3P2821B
3 6
NC
4
5
Pin Description Pin# 1 2 3 4 5 6 7 8 Pin Name XIN VSS NC NC MODOUT NC VDD NC P O Type I P External reference clock input. Ground to entire chip. No Connect. No Connect. Spread spectrum low EMI output. No Connect. Power supply for the entire chip (3.3V). No Connect. Description
Low Power EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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ASM3P2821B
Absolute Maximum Ratings Symbol VDD, VIN TSTG TA Parameter Voltage on any pin with respect to GND Storage temperature Operating temperature Rating -0.5 to + 7.0 -65 to +125 0 to 70 Unit V C 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 VOL VOH ICC IDD VDD tON ZOUT Input low voltage Input high voltage Input low current Input high current Output low voltage (VDD = 3.3V, IOL = 4mA) Output high voltage (VDD = 3.3V, IOH = 4mA) 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 TBD Parameter Min GND - 0.3 TBD Typ TBD TBD TBD TBD TBD TBD 3.3 TBD TBD TBD Max TBD VDD + 0.3 Unit V V A A V V mA A V mS
Low Power EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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ASM3P2821B
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 15 15 Typ 24 24 TBD TBD TBD TBD Max 27 27 Unit MHz MHz ns ns ps %
* tLH and tHL are measured into a capacitive load of 15pF
Low Power EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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ASM3P2821B
Package Information
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
Low Power EMI Reduction IC
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Notice: The information in this document is subject to change without notice.
ASM3P2821B
8-Pin TSSOP
H
E D A2 A e B A1 L C
Symbol A A1 A2 B C D E e H L
Dimensions in inches Min Max 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
Dimensions in millimeters Min Max 1.10 0.05 0.80 0.19 0.09 2.90 4.30 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
0.65 BSC 6.20 0.45 0 6.60 0.75 8
Low Power EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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ASM3P2821B
Alliance Semiconductor Corporation 2595, 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: ASM3P2821B Document Version: v1.0
(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.
Low Power EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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