november 2003 asm3x2105a rev 1.2 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. features ? fcc approved method of emi attenuation. ? generates a 1x or ? x low emi spread spectrum clock of the input frequency. ? input frequency range: 6mhz to 10 mhz. ? internal loop filter minimizes external components and board space. ? frequency deviation: maximum 1%. ? sson# control pin for spread spectrum enable and disable options. ? low cycle-to-cycle jitter. ? 5.0v 5% operating voltage range. ? ttl or cmos compatible outputs. ? ultra-low power cmos design. ? available in 8-pin soic and tssop. product description the asm3x2105a is a versatile spread spectrum frequency modulator designed specifically for input clock frequencies from 6mhz to 10mhz. the asm3x2105a can generate an emi reduced clock from crystal, ceramic resonator, or system clock. the asm3x2105a offers frequency deviation of 1%. the asm3x2105a reduces electromagnetic interference (emi) at the clock source, allowing system wide reduction of emi of down stream clock and data dependent signals. the asm3x2105a 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 asm3x2105a uses the most efficient and optimized modulation profile approved by the fcc and is implemented in a proprietary all digital method. the asm3x2105a 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?. applications the asm3x2105a is targeted towards emi management for high speed digital applications such as pc peripheral devices, consumer electronics and embedded controller systems. block diagram vss xin xout crystal oscillator frequency divider feedback divider modulation phase detector loop filter vco output divider modout pll vdd sson# div2 sr0
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 2 of 10 notice: the information in this document is subject to change without notice. 1 2 3 4 5 6 7 8 asm3x2105a xin /clk xout div2 vss sr0 sson# modout vdd pin configuration pin description pin# pin name type description 1 xin/clk i crystal connection or external refere nce frequency input. this pin has dual functions. it can be connected to either an external crystal or an external reference clock. 2 xout o crystal connection. if using an external reference, this pin must be left unconnected. 3 div2 i digital logic input used to select nor mal output mode or divide-by-2 output mode. when this pin is high, the frequ ency of the output clock is the same as the input clock frequency. when it is tied low, the output frequency is half the input clock frequency. this pin has an internal pull-up resistor. 4 vss p ground to entire chip. 5 sr0 i digital logic input used to select sp reading range (refer spread deviation table). this pin has an internal pull-up resistor. 6 sson# i digital logic input used to enable spread spectrum function (active low). spread spectrum function enabled when low, disabled when high. this pin has an internal pull-low resistor. 7 modout o spread spectrum low emi output. 8 vdd p power supply for the entire chip (5v). spread deviation table sr0 spread deviation (%) 1 1 0 reserved modulation rate = f in /128
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 3 of 10 notice: the information in this document is subject to change without notice. spread spectrum spreading the spectrum of the signal reduces the system emi. the optimal setting should minimize system emi to the fullest without affecting syst em performance. the spreading is desc ribed as a percentage deviation of the center frequency (note: the center frequency is the fr equency of the external reference input on clkin, pin1). example: the asm3x2105a is designed for communications, digital video and imaging applications. it is not only optimized for operation in the 6mhz ? 10mhz range, but its output frequenc y can be extended down to one half of the input clock frequency using the di vide-by-two feature. this feature extends low frequency operation to as low as 3mhz. setting pin 3 low (div2=0; divide-by-two mode) sets the output frequency (modout) to half the frequency of the input clock (clkin). this is a simp le way to generate a spread spectrum modulated low frequency clock when only a higher frequency signal is av ailable. if you want the output frequency to be the same as the input, you can either set div2=1 or leave it unconnected. 1 2 3 4 clkin xout div2 vss modout 5 6 7 8 sr0 sson# vdd 8.832mhz cr y stal modulated 4.416mhz is connected to clk input pin of the system +5v 0.1f asm3x2105a
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 4 of 10 notice: the information in this document is subject to change without notice. emc software simulation by using alliance?s proprietary emc simulation software ? emi-lator?, radiated system level emi analysis can be made easier, allowing quantitative measure on t he benefits of alliance?s emi reduction products. the simulation engine of this emc software has already been characterized to correlate with the electrical characteristics of alliance emi reduct ion ics. the figure below is an illustration of this simulation result. please visit our website at www.alsc.com for information on how to obtain a free copy and demonstration of emi-lator ?. simulation results from emi-lator?
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 5 of 10 notice: the information in this document is subject to change without notice. absolute maximum ratings symbol parameter rating unit v dd , v in voltage on any pin with respect to gnd -0.5 to + 7.0 v t stg storage temperature -65 to +125 c t a operating temperature -25 to +70 c note: these are stress ratings only and functional oper ation is not implied. exposure to absolute maximum ratings for extended periods may affect device reliability. dc electrical characteristics symbol parameter min typ max unit v il input low voltage gnd ? 0.3 - 0.8 v v ih input high voltage 2.0 - v dd + 0.3 v i il input low current (pull-up resistors on inputs sr0 and div2) 44 a i ih input high current (pull-down resistor on input sson#) 66 a i xol x out output low current (@ 4.0v, v dd = 5v) 3 ma i xoh x out output high current (@2.5v, v dd = 5v) 3 ma v ol output low voltage (v dd = 5v, i ol = 20ma) 0.9 v v oh output high voltage (v dd = 5v, i oh = 20ma) 3.5 v i cc dynamic supply current normal mode (5v, 8mhz and 15pf loading) 40 ma i dd static supply current standby mode 40 a v dd operating voltage 4.75 5.0 5.25 v t on power up time (first locked cloc k cycle after power up) - 0.18 - ms z out clock out impedance - 50 - ?
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 6 of 10 notice: the information in this document is subject to change without notice. ac electrical characteristics symbol parameter min typ max unit f in input frequency 6 - 10 mhz modout output frequency 6 - 10 mhz t lh * output rise time (measure d at 0.8v to 2.0v) - 440 - ps t hl * output fall time (measured at 2.0v to 0.8v) - 300 - ps t jc jitter (cycle to cycle) - - 360 ps t d output duty cycle 45 50 55 % * v dd = +5v, input frequency = 8mhz, t lh and t hl are measured into a capacitive load of 15pf
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 7 of 10 notice: the information in this document is subject to change without notice. d e h d a1 a2 a l c b e package information 8-pin soic (pb free parts) symbol dimensions in inches dimensions in millimeters min max min max a 0.057 0.071 1.45 1.80 a1 0.004 0.010 0.10 0.25 a2 0.053 0.069 1.35 1.75 b 0.012 0.020 0.31 0.51 c 0.004 0.01 0.10 0.25 d 0.186 0.202 4.72 5.12 e 0.148 0.164 3.75 4.15 e 0.050 bsc 1.27 bsc h 0.224 0.248 5.70 6.30 l 0.012 0.028 0.30 0.70 0 8 0 8
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 8 of 10 notice: the information in this document is subject to change without notice. e h a a1 a2 d b c l e 8-pin tssop dimensions in inches dimensions in millimeters symbol min max min max a 0.047 1.10 a1 0.002 0.006 0.05 0.15 a2 0.031 0.041 0.80 1.05 b 0.007 0.012 0.19 0.30 c 0.004 0.008 0.09 0.20 d 0.114 0.122 2.90 3.10 e 0.169 0.177 4.30 4.50 e 0.026 bsc 0.65 bsc h 0.244 0.260 6.20 6.60 l 0.018 0.030 0.45 0.75 0 8 0 8
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 9 of 10 notice: the information in this document is subject to change without notice. or - sot23/t/r sr - soic, t/r tt ? tssop, tube qr ? qfn, t/r tr - tssop, t/r qt - qfn, tube vt ? tvsop, tube bt - bga, tube vr ? tvsop, t/r br ? bga, t/r st ? soic, tube f = pb free part number x = automotive i = industrial p or n/c = commercial 1 ? reserved 6 ? power management 2 - non pll based 7 ? power management 3 ? emi reduction 8 ? power management 4 ? ddr support products 9 ? hi performance 5 ? std zero dela y buffe r 0 - reserved alliance semiconductor mixed signal product ordering codes part number package ASM3X2105AFTR 8-pin tssop tape and reel asm3x2105aft 8-pin tssop tube asm3x2105afsr 8-pin soic tape and reel asm3x2105afs 8-pin soic tube device ordering information ASM3X2105AFTR licensed under us patent #5,488,627, # 6,646,463 and #5,631,920.
november 2003 asm3x2105a rev 1.2 low frequency emi reduction 10 of 10 notice: the information in this document is subject to change without notice. ? 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 ch anges to this document and its products at any time without notice. alliance assumes no responsibility for any errors t hat may appear in this document. the data contained herein represents alliance's best data and/or estimate s at the time of issuance. alliance rese rves 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 in tended to operate as, or provide, any guarantee or warrantee to any user or customer. alliance does not assume any responsibility or lia bility arising out of the applic ation or use of any product described herein, and disclaims any express or implied warrant ies related to the sale and/or use of alliance products including liability or warranties related to fitness for a particular purpose, mercha ntability, or infringement of any intellec tual 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 pa tent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of alli ance or third parties. alliance does not aut horize its products for use as critical components in life-supporting systems where a malfunction or fa ilure 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. alliance semiconductor corporation 2575, augustine drive, santa clara, ca 95054 tel# 408-855-4900 fax: 408-855-4999 www.alsc.com copyright ? alliance semiconductor all rights reserved preliminary information part number: asm3x2105a document version: v1.2 note: this product utilizes us patent # 6, 646,463 impedance emulator patent issued to dan hariton / alliance semiconductor, dat ed 11-11-2003
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