asm3p2579a peak emi reducing solution ?2010 scillc. all rights reserved. publication order number: january 2010 C rev. 2 asm3p2579/d features generates an emi optimized clock signal at the output. integrated loop filter components. operates with a 3.3 / 2.5v supply. operating current less than 4ma. cmos design. input frequency range: 12mhz to 30mhz for 2.5v 12mhz to 30mhz for 3.3v generates a 1x low emi spread spectrum clock of the input frequency. spread spectrum enable control. frequency deviation: 1% @ 24mhz available in 6l-tsop (6l-tsot-23). product description the asm3p2579a is a versatile spread spectrum frequency modulator designed specifically for a wid e range of clock frequencies. the asm3p2579a reduces electromagnetic interference (emi) at the clock sou rce, allowing system wide reduction of emi of all clock dependent signals. the asm3p2579a allows significan t system cost savings by reducing the number of circu it board layers, ferrite beads and shielding that are traditionally required to pass emi regulations. -the asm3p2579a uses the most efficient and optimiz ed modulation profile approved by the fcc and is implemented by using a proprietary all digital meth od. the asm3p2579a 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 result in significantly lower s ystem emi compared to the typical narrow band signal prod uced by oscillators and most frequency generators. lower ing emi by increasing a signals bandwidth is called s pread spectrum clock generation. applications the asm3p2579a is targeted towards all portable devices like mp3 players and digital still cameras. key specifications description specification supply voltages vdd = 3.3v/2.5v cycle-to-cycle jitter 200ps (typ) output duty cycle 45/55% (worst case) modulation rate equation f in /640 frequency deviation 1% @ 24mhz block diagram vss modout xin frequency divider feedback divider modulation phase d etector loop filter vco output divider pll crystal oscillator xout sson vdd
asm3p2579a rev. 2 | page 2 of 7 | www.onsemi.com vdd modout xin / clkin xout 1 2 3 4 5 6 asm3p2579a sson vss pin configuration (6l-tsop) pin description pin# pin name type description 1 sson i when sson is high, the spread spectrum is enabled a nd when low, it turns off the spread spectrum. connect the pin to ground when spr ead spectrum feature is not required. 2 xout o crystal connection. if using an external r eference, this pin must be left unconnected. 3 xin / clkin i crystal connection or external reference frequency input. this pin has dual functions. it can be connected either to an external crystal or a n external reference clock. 4 vdd p power supply for the entire chip. 5 modout o spread spectrum clock output. 6 vss p ground connection. absolute maximum ratings symbol parameter rating unit vdd, v in voltage on any pin with respect to ground -0.5 to +4.6 v t stg storage temperature -65 to +125 c t s max. soldering temperature (10 sec) 260 c t j junction temperature 150 c t dv static discharge voltage (as per jedec std22- a114-b) 2 kv note: these are stress ratings only and are not imp lied for functional use. exposure to absolute maxim um ratings for prolonged periods of time may affect device reliability. operating conditions parameter description min max unit vdd supply voltage 2.375 3.6 v t a operating temperature (ambient temperature) -40 + 85 c c l load capacitance 15 pf c in input capacitance 7 pf
asm3p2579a rev. 2 | page 3 of 7 | www.onsemi.com dc electrical characteristics for 2.5v supply symbol parameter min typ max unit v il input low voltage vss-0.3 0.8 v v ih input high voltage 2.0 vdd+0.3 v i il input low current -35 a i ih input high current 35 a i xol xout output low current (@ 0.5v, vdd = 2.5v) 3 m a i xoh xout output high current (@ 1.8v, vdd = 2.5v) 3 ma v ol output low voltage (vdd = 2.5v, i ol = 8ma) 0.6 v v oh output high voltage (vdd = 2.5v, i oh = 8ma) 1.8 v i dd static supply current 1 1.1 ma i cc dynamic supply current (2.5v, 24mhz and no load) 3.5 ma vdd operating voltage 2.375 2.5 2.625 v t on power-up time (first locked cycle after power-up) 5 ms z out output impedance 50 note: 1. xin / clkin is made low. ac electrical characteristics for 2.5v supply symbol parameter min typ max unit clkin input frequency 12 30 mhz modout output frequency 12 30 mhz f d frequency deviation input frequency = 12mhz 1.65 % input frequency = 30mhz 0.80 t lh 1 output rise time (measured from 0.7v to 1.7v) 0.7 1.5 1.9 ns t hl 1 output fall time (measured from 1.7v to 0.7v) 0.4 1.0 1.1 ns t jc jitter (cycle-to-cycle) 200 ps t d output duty cycle 45 50 55 % note: 1. t lh and t hl are measured into a capacitive load of 15pf.
asm3p2579a rev. 2 | page 4 of 7 | www.onsemi.com dc electrical characteristics for 3.3v supply symbol parameter min typ max unit v il input low voltage vss-0.3 0.8 v v ih input high voltage 2.0 vdd+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, vdd = 3.3v) 3 m a i xoh xout output high current (@ 2.5v, vdd = 3.3v) 3 ma v ol output low voltage (vdd = 3.3v, i ol = 8ma) 0.4 v v oh output high voltage (vdd = 3.3v, i oh = 8ma) 2.5 v i dd static supply current 1 1.2 ma i cc dynamic supply current (3.3v, 24mhz and no load) 4.0 ma vdd operating voltage 2.7 3.3 3.6 v t on power-up time (first locked cycle after power-up) 5 ms z out output impedance 45 note: 1. xin / clkin is made low. ac electrical characteristics for 3.3v supply symbol parameter min typ max unit clkin input frequency 12 30 mhz modout output frequency 12 30 mhz f d frequency deviation input frequency = 12mhz 1.65 % input frequency = 30mhz 0.80 t lh 1 output rise time (measured from 0.8 to 2.0v) 0.5 1 .4 1.7 ns t hl 1 output fall time (measured at 2.0v to 0.8v) 0.4 1. 0 1.2 ns t jc jitter (cycle-to-cycle) 200 ps t d output duty cycle 45 50 55 % note: 1. t lh and t hl are measured into a capacitive load of 15pf.
asm3p2579a rev. 2 | page 5 of 7 | www.onsemi.com typical crystal specifications fundamental at cut parallel resonant crystal nominal frequency 14.31818mhz frequency tolerance 50 ppm or better at 25c operating temperature range -25c to +85c storage temperature -40c to +85c load capacitance(c p ) 18pf shunt capacitance 7pf maximum esr 25 w note: note: c l is load capacitance and rx is used to prevent osci llations at overtone frequency of the fundamental f requency. typical crystal interface circuit c l = 2*(c p C c s ), where c p = load capacitance of crystal c s = stray capacitance due to c in, pcb, trace etc. typical application schematic vss vdd 2.2f c2 modout modout clock asm3p2579a 0.1f rs c1 vdd rx c l c l crystal r
asm3p2579a rev. 2 | page 6 of 7 | www.onsemi.com package information 6l-tsop symbol dimensions inches millimeters min max min max a 0.04 1.00 a1 0.00 0.004 0.00 0.10 a2 0.033 0.036 0.84 0.90 b 0.012 0.02 0.30 0.50 h 0.005 bsc 0.127 bsc d 0.114 bsc 2.90 bsc b 0.06 bsc 1.60 bsc e 0.0374 bsc 0.950 bsc c 0.11 bsc 2.80 bsc l 0.0118 0.02 0.30 0.50 0 4 0 4
asm3p2579a note: this product utilizes us patent #6,646,463 im pedance emulator patent issued to pulsecore semicon ductor, dated 11-11-2003. on semiconductor and are registered trademarks of semiconductor componen ts industries, llc (scillc). scillc reserves the ri ght to make changes without further notice to any products herein. sci llc makes no warranty, representation or guarantee regarding the suitability of its products for any p articular purpose, nor does scillc assume any liability arisi ng out of the application or use of any product or circuit, and specifically disclaims any and all lia bility, including without limitation special, consequential or incidental damages. typical parameters which may be provided in scillc data sheets and/or specifications can and do vary in different applica tions and actual performance may vary over time. al l operating parameters, including typicals must b e validated for each customer application by customer 's technical experts. scillc does not convey any l icense under its patent rights nor the rights of ot hers. scillc products are not designed, intended, or auth orized for use as components in systems intended fo r surgical implant into the body, or other applicat ions intended to support or sustain life, or for any oth er application in which the failure of the scillc p roduct could create a situation where personal inju ry or death may occur. should buyer purchase or use scillc pro ducts for any such unintended or unauthorized appli cation, buyer shall indemnify and hold scillc and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs , damages, and expenses, and reasonable attorney fe es arising out of, directly or indirectly, any claim of person al injury or death associated with such unintended or unauthorized use, even if such claim alleges tha t scillc was negligent regarding the design or manufacture o f the part. scillc is an equal opportunity/affirmat ive action employer. u.s patent pending; timing-sa fe and active bead are trademarks of pulsecore semicon ductor, a wholly owned subsidiary of on semiconduct or. this literature is subject to all applicable copyright laws and is not for resale in any manner. publication ordering information literature fulfillment: literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone: 303-675-2175 or 800-344-3860 toll free usa/canada fax: 303-675-2176 or 800-344-3867 toll free usa/canada email: orderlit@onsemi.com n. american technical support: 800-282-9855 toll free usa/canada europe, middle east and africa technical support: phone: 421 33 790 2910 japan customer focus center phone: 81-3-5773-3850 on semiconductor website: www.onsemi.com order literature: http://www.onsemi.com/orderlit for additional information, please contact your local sales representative ordering information part number marking package type temperature ASM3I2579AF-06OR s5l 6l-tsop (6l-tsot-23), tape & reel, pb free -40c to +85c a microdot placed at the end of last row of marki ng or just below the last row toward the center of package indicates pb-free. licensed under us patent #5,488,627 and #5,631,921.
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