? semiconductor components industries, llc, 2011 august, 2011 ? rev. p3 1 publication order number: asm3p2508a/d asm3p2508a product preview peak emi reducing solution description the asm3p2508a is a versatile spread spectrum frequency modulator. the asm3p2508a reduces electromagnetic interference (emi) at the clock source. the asm3p2508a allows significant system cost savings by reducing the number of circuit board layers and shielding that are required to pass emi regulations. the asm3p2508a modulates the output of pll in order to spread the bandwidth of a synthesized clock, thereby decreasing 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 clock generators. lowering emi by increasing a signal?s bandwidth is called spread spectrum clock generation. the asm3p2508a has a feature to power down the 72 mhz / 48 mhz output by writing data into specific registers in the device via i2c. by writing a ?0? into bit 1 of byte 0, the pll block generating 72 mhz / 48 mhz can be powered down. writing ?0? into bit ?7? of byte 1 selects an output of 72 mhz on fout2clk while a ?1? at the same location selects a 48 mhz clock output. however, the i2c block, crystal oscillator, and the pll block generating 120 mhz would be always running. features ? generates an emi optimized clocking signal at output ? input frequency ? 14.31818 mhz ? frequency outputs: ? 120 mhz (modulated) ? default ? 72 mhz (modulated) or 48 mhz (modulated) selectable via i2c ? 1% centre spread ? modulation rate: 40 khz ? byte write via i2c ? supply voltage range 3.3 v 0.3 v ? available in 8 ? pin soic package ? available in commercial and industrial ? temperature ranges ? these devices are pb ? free, halogen free/bfr free and are rohs compliant this document contains information on a product under development. on semiconductor reserves the right to change or discontinue this product without notice. http://onsemi.com soic ? 8 s suffix case 751bd pin configuration (top view) see detailed ordering and shipping information in the package dimensions section on page 8 of this data sheet. ordering information v ss scl sda fout2clk xout v dd xin 1 fout1clk
asm3p2508a http://onsemi.com 2 figure 1. block diagram scl sda xin xout v dd pll 1 v ss pll 2 fout1clk (120 mhz) fout2clk (72 mhz / 48 mhz) crystal oscillator i2c interface table 1. pin description pin name type description xin i connection to crystal xout o connection to crystal v dd p power supply for the analog and digital blocks fout1clk o clock output ? 1 (120 mhz) ? default fout2clk o clock output ? 2 (72 mhz / 48 mhz) sda i/o i2c data scl i i2c clock v ss p ground to entire chip table 2. absolute maximum ratings symbol parameter rating unit v dd , v in voltage on any pin with respect to ground ? 0.5 to +4.6 v t stg storage temperature ? 40 to +85 c t a operating temperature 0 to 70 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 stresses exceeding maximum ratings may damage the device. maximum ratings are stress ratings only. functional operation above t he recommended operating conditions is not implied. extended exposure to stresses above the recommended operating conditions may af fect device reliability. table 3. operating conditions symbol parameter condition / description min typ max unit v dd supply voltage 3.3 v 10% 3 3.3 3.6 v t a ambient operating temperature range ? 10 +70 c f xin crystal resonator frequency 14.31818 mhz serial data transfer rate standard mode 10 100 kb/s c l output driver load capacitance 15 pf
asm3p2508a http://onsemi.com 3 table 4. dc electrical characteristics (test condition: all the parameters are measured at room temperature (25 c), unless otherwise stated.) parameter symbol conditions / description min typ max unit overall supply current, dynamic i cc v dd = 3.3 v, f clk = 14.31818 mhz, c l = 15 pf 40 49 60 ma supply current, static i dd v dd = 3.3 v, software power down (note 1) 27 35 43 ma all input pins high ? level input voltage v ih v dd = 3.3 v 2.0 ? v dd +0.3 v low ? level input voltage v il v dd = 3.3 v v ss ? 0.3 ? 0.8 v high ? level input current i ih ? 1 ? 1 a low ? level input current (pull ? up) i il ? 20 ? 36 ? 80 a clock outputs (fout1clk, fout2clk ) high ? level output voltage v oh v dd = 3.3 v, i oh = 20 ma 2.5 ? 3.3 v low ? level output voltage v ol v dd = 3.3 v, i ol = 20 ma 0 ? 0.4 v output impedance z oh v o = 0.5 v dd ; output driving high ? 29 ? z ol vo = 0.5 v dd ; output driving low ? 27 ? 1. fout1clk (120 mhz) is functional and not loaded. table 5. ac electrical characteristics parameter symbol conditions / description min typ max unit rise time t r v o = 0.8 v to 2.0 v; c l = 15 pf fout1clk 640 680 750 ps fout2clk 440 480 600 fall time t f v o = 2.0 v to 0.8 v; c l = 15 pf fout1clk 660 720 800 ps fout2clk 460 520 570 clock duty cycle t d ratio of pulse width (as measured from rising edge to next falling edge at 2.5 v) to one clock period 45 ? 55 % frequency deviation f d output frequency = 120 mhz ? 2.73 ? % output frequency = 72 mhz / 48 mhz ? 1.78 ? jitter, long term tj (lt) on rising edges 500 s apart at 2.5 v relative to an ideal clock, pll b inactive (note 2) ? 45 ? ps on rising edges 500 s apart at 2.5 v relative to an ideal clock, pll b active (note 2) ? 165 ? jitter, peak to peak tj ( t) from rising edge to next rising edge at 2.5 v, pll b inactive (note 2) ? 110 ? ps from rising edge to next rising edge at 2.5 v, pll b active (note 2) ? 390 ? clock stabilization time t stb output active from power up, run mode via software power down ? 125 ? s 2. cl = 15 pf, fxin = 14.31818 mhz.
asm3p2508a http://onsemi.com 4 figure 2. typical crystal oscillator circuit c2 = 27 pf c1 = 27 pf r1 = 510 crystal table 6. typical crystal specifications fundamental at cut parallel resonant crystal nominal frequency 14.31818 mhz frequency tolerance 50 ppm or better at 25 c operating temperature range ? 20 c to +85 c storage temperature ? 40 c to +85 c load capacitance 18 pf shunt capacitance 7 pf maximum esr 25
asm3p2508a http://onsemi.com 5 i2c serial interface information the information in this section assumes familiarity with i2c programming. how to program asm3p2508a through i2c: ? master (host) sends a start bit. ? master (host) sends the write address d4 (h). ? asm3p2508a device will acknowledge. ? master (host) sends the beginning byte location (n = 0, 1). ? asm3p2508a device will acknowledge. ? master (host) sends a byte count (x = 1, 2). ? asm3p2508a device will acknowledge. ? master (host) starts sending byte n through byte (n+x ? 1). ? asm3p2508a device will acknowledge each byte one at a time. ? master (host) sends a stop bit. controller (host) asm3p2508a (slave/receiver) start bit slave address d4 (h) ack beginning byte location (=n) ack byte count (=x) ack beginning byte (byte n) ack next byte (byte n+1) ack ??????? ???? last byte (byte n+x ? 1) ack stop bit how to read from asm3p2508a through i2c: ? master (host) will send start bit. ? master (host) sends the write address d4 (h). ? asm3p2508a device will acknowledge. ? master (host) sends the beginning byte location (n = 0, 1). ? asm3p2508a device will acknowledge. ? master (host) will send a separate start bit. ? master (host) sends the read address d5 (h). ? asm3p2508a device will acknowledge. ? asm3p2508a device will send the byte count (x = 1, 2). ? master (host) acknowledges. ? asm3p2508a device sends byte n through byte (n+x ? 1). ? master (host) will need to acknowledge each byte. ? master (host) will send a stop bit. controller (host) asm3p2508a (slave/receiver) start bit slave address d4 (h) ack beginning byte = n ack repeat start slave address d5 (h) ack byte count (= x) ack beginning byte n ack next byte n+1 ack ???? ??????? last byte (byte n+x ? 1) not acknowledge stop bit
asm3p2508a http://onsemi.com 6 an example of a byte write via i2c to partially ?power down? the device: asm3p2508a can be partially ?powered down? using bit 1 of byte 0. the organization of the register bits for byte ?0? is given with default values below: bit 7 6 5 4 3 2 1 0 resv resv resv resv resv resv pll2 enable pll1 enable 0 1 0 1 0 1 1 1 the function of partial power down of the device is of interest to us ? that is bit 1 of byte 0. in the default mode this bit is logic ?1?. as such, the byte 0 default value is 57 (h). to put asm3p2508a in ?power down? mode, the bit 1 of byte 0 is to be changed to logic ?0?. hence writing a 55 (h) via i2c into byte 0 would put the device in partial ?power down? mode where the pll block generating 72 mhz / 48 mhz would be powered down while i2c block, crystal oscillator, and the pll block generating 120 mhz would still be active. the organization of the register bits is as below: bit 7 6 5 4 3 2 1 0 resv resv resv resv resv resv pll2 enable pll1 enable 0 1 0 1 0 1 0 1 byte 0 byte 1 fout1clk (mhz) fout2clk (mhz) power up default 6f (h) 3f (h) 120 72 48_mhz mode 6f (h) bf (h) 120 48 power down pll with 72 mhz 6d (h) 3f (h) 120 ? power down pll with 48 mhz 6d (h) bf (h) 120 ? figure showing a complete data transfer:
asm3p2508a http://onsemi.com 7 package dimensions soic 8, 150 mils case 751bd ? 01 issue o e1 e a a1 h l c e b d pin # 1 identification top view side view end view notes: (1) all dimensions are in millimeters. angles in degrees. (2) complies with jedec ms-012. symbol min nom max a a1 b c d e e1 e h 0o 8o 0.10 0.33 0.19 0.25 4.80 5.80 3.80 1.27 bsc 1.75 0.25 0.51 0.25 0.50 5.00 6.20 4.00 l 0.40 1.27 1.35
asm3p2508a http://onsemi.com 8 table 7. ordering information part number marking package type temperature asm3p2508ag ? 08st 3p2508ag 8 ? pin soic, tube, green commercial asm3p2508ag ? 08sr 3p2508ag 8 ? pin soic, tape and reel, green commercial asm3i2508ag ? 08st 3i2508ag 8 ? pin soic, tube, green industrial asm3i2508ag ? 08sr 3i2508ag 8 ? pin soic, tape and reel, green industrial asm3p2508af ? 08st 3p2508af 8 ? pin soic, tube, pb free commercial asm3p2508af ? 08sr 3p2508af 8 ? pin soic, tape and reel, pb free commercial asm3i2508af ? 08st 3i2508af 8 ? pin soic, tube, pb free industrial asm3i2508af ? 08sr 3i2508af 8 ? pin soic, tape and reel, pb free industrial on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for an y particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including wi thout 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 application s and actual performance may vary over time. all operating parameters, including ?typicals? must be validated for each customer application by customer?s technical experts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc product could create a sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indemnify and hold scillc and its of ficers, employees, subsidiaries, af filiates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, direct ly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. this literature is subject to all applicable copyright laws and is not for resale in any manner. asm3p2508a/d publication ordering information 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 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 on semiconductor website : www.onsemi.com order literature : http://www.onsemi.com/orderlit for additional information, please contact your local sales representative
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