november 2003 asm3p2185b rev 1.1 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. 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 0.8%. ? 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. product description the asm3p2185b is a versatile spread spectrum frequency modulator designed specifically for a wide range of input clock frequencies from 25mhz to 50mhz. the asm3p2185b can generate an emi reduced clock from an osc or a system generated clock. the asm3p2185b reduces electromagnetic interference (emi) at the clock source, allowing system wide emi reduction for all the down stream clocks and data dependent signals. the asm3p2185b 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 asm3p2185b uses the most efficient and optimized modulation profile approved by the fcc and is implemented in a proprietary all digital method. the asm3p2185b 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 asm3p2185b 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 vss xin crystal oscillator frequenc y feedback divide r modulation phase detecto r loop filte r vco output divide r modout pll vdd ss% xout
november 2003 asm3p2185b rev 1.1 emi reduction ic 2 of 7 notice: the information in this document is subject to change without notice. 1 2 3 4 5 6 7 8 asm3p2185b xin xout gnd ss% modout vdd nc nc pin configuration pin description pin# pin name type description 1 xin 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 i crystal connection. input connection for an external crystal. if using an external reference, this pin must be left unconnected. 3 gnd p ground to entire chip. 4 ss% i spread range select. digital logic input used to select frequency deviation (refer spread deviation table ). this pin has an internal pull-up resistor. 5 modout o spread spectrum low emi output. 6 vdd p power supply for the entire chip (3.3v). 7 nc no connect. 8 nc no connect. spread deviation selection table ss% (pin 4) spread deviation (%) 0 - 1.25 1 0.8%
november 2003 asm3p2185b rev 1.1 emi reduction ic 3 of 7 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 0 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 - - -35 a i ih input high current - - 35 a i xol xout output low current (@ 0.4v, v dd = 3.3v) - tbd - ma i xoh xout output high current (@ 2.5v, v dd = 3.3v) - tbd - ma v ol output low voltage (v dd = 3.3v, i ol = 20ma) - - 0.4 v v oh output high voltage (v dd = 3.3v, i oh = 20ma) 2.5 - - v i cc dynamic supply current normal mode (3.3v and 10pf loading) 8.46 12 17.78 ma i dd static supply current standby mode 0.6 ma v dd operating voltage 2.7 3.3 3.7 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 asm3p2185b rev 1.1 emi reduction ic 4 of 7 notice: the information in this document is subject to change without notice. ac electrical characteristics symbol parameter min typ max unit xin input frequency 25 - 50 mhz modout output frequency 25 - 50 mhz t lh * output rise time (measured at 0.8v to 2.0v) 1.2 1.32 1.4 ns t hl * output fall time (measured at 2.0v to 0.8v) 0.8 0.9 1.0 ns t jc jitter (cycle to cycle) - - 360 ps t d output duty cycle 45 50 55 % t lh and t hl are measured into a capacitive load of 15pf
november 2003 asm3p2185b rev 1.1 emi reduction ic 5 of 7 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 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 asm3p2185b rev 1.1 emi reduction ic 6 of 7 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 licensed under us patent #5,488,627, # 6,646,463 and #5,631,920.
november 2003 asm3p2185b rev 1.1 emi reduction ic 7 of 7 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: asm3p2185b document version: v1.1 note: this product utilizes us patent # 6,646,463 impedance emulator patent issued to alliance semiconductor, dated 11-11-2003
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