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filterless, high efficiency, mono 2.5 w class-d audio amplifier ssm2377 rev. 0 information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 www.analog.com fax: 781.461.3113 ?2011 analog devices, inc. all rights reserved. features filterless, class-d amplifier with spread-spectrum - modulation 2.5 w into 4 load and 1.4 w into 8 load at 5.0 v supply with <1% total harmonic distortion plus noise (thd + n) 92% efficiency at 5.0 v, 1.4 w into 8 speaker >100 db signal-to-noise ratio (snr) high psrr at 217 hz: 80 db ultralow emi emissions single-supply operation from 2.5 v to 5.5 v gain select function: 6 db or 12 db fixed input impedance of 80 k 100 na shutdown current short-circuit and thermal protection with autorecovery available in a 9-ball, 1.2 mm 1.2 mm wlcsp pop-and-click suppression applications mobile phones mp3 players portable electronics general description the ssm2377 is a fully integrated, high efficiency, class-d audio amplifier. it is designed to maximize performance for mobile phone applications. the application circuit requires a minimum of external components and operates from a single 2.5 v to 5.5 v supply. it is capable of delivering 2.5 w of continuous output power with <1% thd + n driving a 4 load from a 5.0 v supply. the ssm2377 features a high efficiency, low noise modulation scheme that requires no external lc output filters. the modu- lation operates with high efficiency even at low output power. the ssm2377 operates with 92% efficiency at 1.4 w into 8 from a 5.0 v supply and has an snr of >100 db. spread-spectrum pulse density modulation (pdm) is used to provide lower emi-radiated emissions compared with other class-d architectures. the inherent randomized nature of spread-spectrum pdm eliminates the clock intermodulation (beating effect) of several amplifiers in close proximity. the ssm2377 produces ultralow emi emissions that signifi- cantly reduce the radiated emissions at the class-d outputs, particularly above 100 mhz. the ssm2377 passes fcc class b radiated emission testing with 50 cm, unshielded speaker cable without any external filtering. the ultralow emi emissions of the ssm2377 are also helpful for antenna and rf sensitivity problems. the device is configured for either a 6 db or a 12 db gain setting by connecting the gain pin to the vdd pin or the gnd pin, respectively. input impedance is a fixed value of 80 k, indepen- dent of the gain select operation. the ssm2377 has a micropower shutdown mode with a typical shutdown current of 100 na. shutdown is enabled by applying a logic low to the sd pin. the device also includes pop-and-click suppression circuitry, which minimizes voltage glitches at the output during turn-on and turn-off, reducing audible noise on activation and deactivation. built-in input low-pass filtering is also included to suppress out- of-band noise interference to the pdm modulator. the ssm2377 is specified over the industrial temperature range of ?40 c to +85 c. it has built-in thermal shutdown and output short-circuit protection. it is available in a halide-free, 9-ball, 0.4 mm pitch, 1.2 mm 1.2 mm wafer level chip scale package (wlcsp). functional block diagram fet driver modulator ( - ) 0.1f vdd out+ out? bias in+ 80k? 80k? power supply 2.5v to 5.5v in? internal oscillator pop/click and emi suppression gnd 10f 22nf 22nf shutdown sd gain select audio in+ audio in? ssm2377 gain gain = 6db or 12db 09824-001 figure 1.
ssm2377 rev. 0 | page 2 of 16 table of contents features .............................................................................................. 1 ? applications ....................................................................................... 1 ? general description ......................................................................... 1 ? functional block diagram .............................................................. 1 ? revision history ............................................................................... 2 ? specifications ..................................................................................... 3 ? absolute maximum ratings ............................................................ 5 ? thermal resistance ...................................................................... 5 ? esd caution .................................................................................. 5 ? pin configuration and function descriptions ............................. 6 ? typical performance characteristics ............................................. 7 ? typical application circuits .......................................................... 12 ? theory of operation ...................................................................... 13 ? overview ..................................................................................... 13 ? gain selection ............................................................................. 13 ? pop-and-click suppression ...................................................... 13 ? emi noise .................................................................................... 13 ? output modulation description .............................................. 13 ? layout .......................................................................................... 14 ? input capacitor selection .......................................................... 14 ? power supply decoupling ......................................................... 14 ? outline dimensions ....................................................................... 15 ? ordering guide .......................................................................... 15 ? revision history 5 /11revision 0: initial version
ssm2377 rev. 0 | page 3 of 16 specifications v dd = 5.0 v, t a = 25c, r l = 8 +33 h, unless otherwise noted. table 1. parameter symbol test conditions/comments min typ max unit device characteristics output power p out f = 1 khz, 20 khz bw r l = 8 , thd = 1%, v dd = 5.0 v 1.41 w r l = 8 , thd = 1%, v dd = 3.6 v 0.72 w r l = 8 , thd = 1%, v dd = 2.5 v 0.33 w r l = 8 , thd = 10%, v dd = 5.0 v 1.78 w r l = 8 , thd = 10%, v dd = 3.6 v 0.90 w r l = 8 , thd = 10%, v dd = 2.5 v 0.41 w r l = 4 , thd = 1%, v dd = 5.0 v 2.49 w r l = 4 , thd = 1%, v dd = 3.6 v 1.25 w r l = 4 , thd = 1%, v dd = 2.5 v 0.54 w r l = 4 , thd = 10%, v dd = 5.0 v 3.17 1 w r l = 4 , thd = 10%, v dd = 3.6 v 1.56 w r l = 4 , thd = 10%, v dd = 2.5 v 0.68 w efficiency p out = 1.4 w into 8 , v dd = 5.0 v 92.4 % total harmonic distortion plus noise thd + n p out = 1 w into 8 , f = 1 khz, v dd = 5.0 v 0.007 % p out = 0.5 w into 8 , f = 1 khz, v dd = 3.6 v 0.009 % input common-mode voltage range v cm 1.0 v dd ? 1 v common-mode rejection ratio cmrr 100 mv rms at 1 khz 51 db average switching frequency f sw 256 khz clock frequency f osc 6.2 mhz differential output offset voltage v oos gain = 6 db 0.4 5.0 mv power supply supply voltage range v dd guaranteed from psrr test 2.5 5.5 v power supply rejection ratio inputs are ac-grounded, c in = 0.1 f, gain = 6 db psrr gsm v ripple = 100 mv at 217 hz 80 db psrr v ripple = 100 mv at 1 khz 80 db supply current i sy v in = 0 v, no load, v dd = 5.0 v 2.5 ma v in = 0 v, no load, v dd = 3.6 v 2.0 ma v in = 0 v, no load, v dd = 2.5 v 1.9 ma v in = 0 v, r l = 8 + 33 h, v dd = 5.0 v 2.5 ma v in = 0 v, r l = 8 + 33 h, v dd = 3.6 v 2.0 ma v in = 0 v, r l = 8 + 33 h, v dd = 2.5 v 1.8 ma shutdown current i sd sd = gnd 100 na gain control closed-loop gain gain gain = gnd 12 db gain = vdd 6 db input impedance z in sd = vdd, gain = 6 db or 12 db 80 k shutdown control input voltage high v ih 1.35 v input voltage low v il 0.35 v turn-on time t wu sd rising edge from gnd to vdd 12.5 ms turn-off time t sd sd falling edge from vdd to gnd 5 s output impedance z out sd = gnd 100 k
ssm2377 rev. 0 | page 4 of 16 parameter symbol test conditions/comments min typ max unit noise performance output voltage noise e n f = 20 hz to 20 khz, inputs are ac-grounded, gain = 6 db, a-weighted v dd = 5.0 v 30 v v dd = 3.6 v 30 v signal-to-noise ratio snr p out = 1.4 w, r l = 8 , a-weighted 101 db 1 although the ssm2377 has good audio quality above 3 w, continuous output power beyond 3 w must be avoided due to device packag ing limitations.
ssm2377 rev. 0 | page 5 of 16 absolute maximum ratings absolute maximum ratings apply at 25c, unless otherwise noted. table 2. parameter rating supply voltage 6 v input voltage v dd common-mode input voltage v dd storage temperature range ?65c to +150c operating temperature range ?40c to +85c junction temperature range ?65c to +165c lead temperature (soldering, 60 sec) 300c esd susceptibility 4 kv stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. thermal resistance junction-to-air thermal resistance ( ja ) is specified for the worst- case conditions, that is, a device soldered in a printed circuit board (pcb) for surface-mount packages. ja is determined according to jedec jesd51-9 on a 4-layer pcb with natural convection cooling. table 3. thermal resistance package type pcb ja unit 9-ball, 1.2 mm 1.2 mm wlcsp 2s2p 88 c/w esd caution
ssm2377 rev. 0 | page 6 of 16 pin configuration and fu nction descriptions top view (ball side down) not to scale 09824-002 a 3 2 1 b c in+ sd gain vdd out? in? gnd vdd out+ ball a1 corner figure 2. pin configuration table 4. pin function descriptions pin no. mnemonic description a1 in+ noninverting input. b1 vdd power supply. c1 in? inverting input. a2 gain gain selection pin. b2 vdd power supply. c2 sd shutdown input. active low digital input. a3 out? inverting output. b3 gnd ground. c3 out+ noninverting output.
ssm2377 rev. 0 | page 7 of 16 typical performance characteristics 100 10 1 0.1 0.01 0.001 0.0001 10 thd + n (%) output power (w) 0.001 0.01 0.1 1 r l = 8 ? + 33h gain = 6db v dd = 2.5v v dd = 5v 09824-003 v dd = 3.6v 100 10 1 0.1 0.01 0.001 0.0001 10 thd + n (%) output power (w) 09824-004 0.001 0.01 0.1 1 r l = 8 ? + 33h gain = 12db v dd = 2.5v v dd = 3.6v v dd = 5v figure 3. thd + n vs. output power into 8 , gain = 6 db figure 6. thd + n vs. output power into 8 , gain = 12 db 100 10 1 0.1 0.01 0.001 0.0001 10 thd + n (%) output power (w) 0.001 0.01 0.1 1 r l = 4 ? + 15h gain = 6db v dd = 2.5v v dd = 3.6v v dd = 5v 09824-005 100 10 1 0.1 0.01 0.001 0.0001 10 thd + n (%) output power (w) 0.001 0.01 0.1 1 r l = 4 ? + 15h gain = 12db v dd = 2.5v v dd = 5v 09824-006 v dd = 3.6v figure 4. thd + n vs. output power into 4 , gain = 6 db figure 7. thd + n vs. output power into 4 , gain = 12 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 09824-008 100 1k 10k v dd = 5v gain = 12db r l = 8 ? + 33h 1w 0.5w 0.25w 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 09824-007 100 1k 10k v dd = 5v gain = 6db r l = 8 ? + 33h 1w 0.5w 0.25w figure 5. thd + n vs. frequency, v dd = 5 v, r l = 8 , gain = 6 db figure 8. thd + n vs. frequency, v dd = 5 v, r l = 8 , gain = 12 db
ssm2377 rev. 0 | page 8 of 16 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 5v gain = 6db r l = 4 ? + 15h 2w 0.5w 1w 09824-009 figure 9. thd + n vs. frequency, v dd = 5 v, r l = 4 , gain = 6 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 3.6v gain = 6db r l =8 ? + 33h 0.25w 0.125w 0.5w 09824-011 figure 10. thd + n vs. frequency, v dd = 3.6 v, r l = 8 , gain = 6 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 3.6v gain = 6db r l = 4 ? + 15h 0.25w 0.5w 1w 09824-013 figure 11. thd + n vs. frequency, v dd = 3.6 v, r l = 4 , gain = 6 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 5v gain = 12db r l = 4 ? + 15h 2w 0.5w 1w 09824-010 figure 12. thd + n vs. frequency, v dd = 5 v, r l = 4 , gain = 12 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 3.6v gain = 12db r l =8 ? + 33h 0.25w 0.5w 09824-012 0.125w figure 13. thd + n vs. frequency, v dd = 3.6 v, r l = 8 , gain = 12 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 3.6v gain = 12db r l = 4 ? + 15h 0.25w 0.5w 1w 09824-014 figure 14. thd + n vs. frequency, v dd = 3.6 v, r l = 4 , gain = 12 db
ssm2377 rev. 0 | page 9 of 16 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 2.5v gain = 6db r l = 8 ? + 33h 0.125w 0.25w 09824-015 0.0625w figure 15. thd + n vs. frequency, v dd = 2.5 v, r l = 8 , gain = 6 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 2.5v gain = 6db r l = 4 ? + 15h 0.125w 0.25w 0.5w 09824-017 figure 16. thd + n vs. frequency, v dd = 2.5 v, r l = 4 , gain = 6 db 2.5 3.0 3.5 4.0 4.5 5.0 5.5 quiescent current (ma) supply voltage (v) 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 gain = 6db no load r l = 4 ? + 15h 09824-019 r l = 8 ? + 33h figure 17. quiescent current vs. supply voltage, gain = 6 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 2.5v gain = 12db r l = 8 ? + 33h 0.125w 0.25w 09824-016 0.0625w figure 18. thd + n vs. frequency, v dd = 2.5 v, r l = 8 , gain = 12 db 100 10 1 0.1 0.01 0.001 10 100k thd + n (%) frequency (hz) 100 1k 10k v dd = 2.5v gain = 12db r l = 4 ? + 15h 0.125w 0.25w 0.5w 09824-018 figure 19. thd + n vs. frequency, v dd = 2.5 v, r l = 4 , gain = 12 db 2.5 3.0 3.5 4.0 4.5 5.0 5.5 quiescent current (ma) supply voltage (v) 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 gain = 12db no load r l = 4 ? + 15h 09824-020 r l = 8 ? + 33h figure 20. quiescent current vs. supply voltage, gain = 12 db
ssm2377 rev. 0 | page 10 of 16 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 2.5 3.0 3.5 4.0 4.5 5.0 output power (w) supply voltage (v) f = 1khz gain = 6db r l = 8 ? + 33h thd + n = 10% thd + n = 1% 09824-021 figure 21. maximum output power vs. supply voltage, r l = 8 , gain = 6 db 3.5 2.0 2.5 3.0 1.5 1.0 0.5 0 2.5 3.0 3.5 4.0 4.5 5.0 output power (w) supply voltage (v) f = 1khz gain = 6db r l = 4 ? + 15h thd + n = 10% thd + n = 1% 09824-023 figure 22. maximum output power vs. supply voltage, r l = 4 , gain = 6 db 100 90 80 70 60 50 40 30 20 10 0 0 0.20.40.60.81.01.21.41.61.82.0 efficiency (%) output power (w) v dd = 2.5v v dd = 3.6v v dd = 5v r l = 8 ? + 33h gain = 6db 09824-025 figure 23. efficiency vs. output power into 8 , gain = 6 db 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 2.5 3.0 3.5 4.0 4.5 5.0 output power (w) supply voltage (v) f = 1khz gain = 12db r l = 8 ? + 33h thd + n = 10% thd + n = 1% 09824-022 figure 24. maximum output power vs. supply voltage, r l = 8 , gain = 12 db 3.5 2.0 2.5 3.0 1.5 1.0 0.5 0 2.5 3.0 3.5 4.0 4.5 5.0 output power (w) supply voltage (v) f = 1khz gain = 12db r l = 4 ? + 15h thd + n = 10% thd + n = 1% 09824-024 figure 25. maximum output power vs. supply voltage, r l = 4 , gain = 12 db 100 90 80 70 60 50 40 30 20 10 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2.0 2.2 efficiency (%) output power (w) 1.8 v dd = 2.5v v dd = 3.6v v dd = 5v r l = 4 ? + 15h gain = 6db 09824-026 figure 26. efficiency vs. output power into 4 , gain = 6 db
ssm2377 rev. 0 | page 11 of 16 500 0 02 supply current (ma) output power (w) 50 100 150 200 250 300 400 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 . 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2.0 2.2 1.8 600 500 0 supply current (ma) output power (w) 100 200 300 400 v dd = 2.5v v dd = 3.6v v dd = 5v r l = 4 ? + 15h gain = 6db 09824-028 450 350 v dd = 2.5v v dd = 3.6v v dd = 5v r l = 8 ? + 33h gain = 6db 09824-027 figure 27. supply current vs. output power into 8 , gain = 6 db figure 30. supply current vs. output power into 4 , gain = 6 db 0 10 100k psrr (db) frequency (hz) 100 1k 10k ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 v dd = 5v r l = 8 ? + 33h gain = 12db gain = 6db 09824-030 0 ?100 10 100k cmrr (db) frequency (hz) 100 1k 10k ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 v dd = 5v r l = 8 ? + 33h gain = 12db gain = 6db 09824-029 figure 28. common-mode rejection ratio (cmrr) vs. frequency figure 31. power supply rejectio n ratio (psrr) vs. frequency 7 6 5 4 3 2 1 0 ?1 ?8 ?4 363228242016 12 840 voltage (v) time (ms) sd input output 09824-031 7 6 5 4 3 2 1 0 ?50 ?30 ?10 10 30 50 70 voltage (v) time (s) sd input output 09824-032 figure 29. turn-on response figure 32. turn-off response
ssm2377 rev. 0 | page 12 of 16 typical application circuits fet driver modulator ( - ) 0.1f vdd out+ out? bias in+ 80k? 80k? power supply 2.5v to 5.5v in? internal oscillator pop/click and emi suppression gnd 10f 22nf 22nf shutdown sd gain select audio in+ audio in? ssm2377 gain gain = 6db or 12db 09824-033 figure 33. monaural differential input configuration fet driver modulator ( - ) 0.1f vdd out+ out? bias in+ 80k? 80k? power supply 2.5v to 5.5v in? internal oscillator pop/click and emi suppression gnd 10f 22nf 22nf shutdown sd gain select audio in? ssm2377 gain gain = 6db or 12db 09824-034 figure 34. monaural single -ended input configuration
ssm2377 rev. 0 | page 13 of 16 theory of operation overview the ssm2377 mono class-d audio amplifier features a filterless modulation scheme that greatly reduces the external component count, conserving board space and, thus, reducing system cost. the ssm2377 does not require an output filter but, instead, relies on the inherent inductance of the speaker coil and the natural filtering of the speaker and human ear to fully recover the audio component of the square wave output. m ost class-d amplifiers use some variation of pulse-width modulation (pwm), but the ssm2377 uses - modulation to determine the switching pattern of the output devices, resulting in a number of important benefits. ? - modulators do not produce a sharp peak with many harmonics in the am frequency band, as pulse-width modulators often do. ? - modulation provides the benefits of reducing the amplitude of spectral components at high frequencies, that is, reducing emi emissions that might otherwise be radiated by speakers and long cable traces. ? due to the inherent spread-spectrum nature of - modu- lation, the need for oscillator synchronization is eliminated for designs that incorporate multiple ssm2377 amplifiers. the ssm2377 also integrates overcurrent and overtemperature protection. gain selection the preset gain of the ssm2377 can be set to 6 db or 12 db using the gain pin, as shown in table 5 . table 5. gain pin function description gain setting (db) gain pin configuration 6 tie to vdd 12 tie to gnd pop-and-click suppression voltage transients at the output of audio amplifiers can occur when shutdown is activated or deactivated. voltage transients as low as 10 mv can be heard as an audible pop in the speaker. clicks and pops can also be classified as undesirable audible transients generated by the amplifier system and, therefore, as not coming from the system input signal. the ssm2377 has a pop-and-click suppression architecture that reduces these output transients, resulting in noiseless activation and deactivation from the sd control pin. emi noise the ssm2377 uses a proprietary modulation and spread-spectrum technology to minimize emi emissions from the device. for applications that have difficulty passing fcc class b emission tests or experience antenna and rf sensitivity problems, the ultralow emi architecture of the ssm2377 significantly reduces the radiated emissions at the class-d outputs, particularly above 100 mhz. figure 35 shows the low radiated emissions from the ssm2377 due to its ultralow emi architecture. 60 50 40 30 20 10 0 electric field strength (dbv/m) 30 130 230 330 430 530 frequency (mhz) 630 730 830 930 1000 + + + + 09824-035 fcc class b limit horizontal polarization vertical polarization figure 35. emi emissions from the ssm2377 the measurements for figure 35 were taken in an fcc-certified emi laboratory with a 1 khz input signal, producing 1.0 w of output power into an 8 load from a 5.0 v supply. the ssm2377 passed fcc class b limits with 50 cm, unshielded twisted pair speaker cable. note that reducing the power supply voltage greatly reduces radiated emissions. output modulation description the ssm2377 uses three-level, - output modulation. each output can swing from gnd to v dd and vice versa. ideally, when no input signal is present, the output differential voltage is 0 v because there is no need to generate a pulse. in a real-world situation, noise sources are always present. due to the constant presence of noise, a differential pulse is generated, when required, in response to this stimulus. a small amount of current flows into the inductive load when the differ- ential pulse is generated. most of the time, however, the output differential voltage is 0 v, due to the analog devices, inc., three-level, - output modula- tion. this feature ensures that the current flowing through the inductive load is small.
ssm2377 rev. 0 | page 14 of 16 when the user wants to send an input signal, an output pulse (out+ and out?) is generated to follow the input voltage. the differential pulse density (v out ) is increased by raising the input signal level. figure 36 depicts three-level, - output modulation with and without input stimulus. output > 0v +5v 0v out+ +5v 0v out? +5v 0v v out output < 0v +5v 0v out+ +5v 0v out? 0v ?5v v out output = 0v out+ +5v 0v +5v 0v out? +5v ?5v 0v v out 0 9824-037 figure 36. three-level, - output modulation with and without input stimulus layout as output power increases, care must be taken to lay out pcb traces and wires properly among the amplifier, load, and power supply. a good practice is to use short, wide pcb tracks to decrease voltage drops and minimize inductance. ensure that track widths are at least 200 mil for every inch of track length for lowest dcr, and use 1 oz or 2 oz copper pcb traces to further reduce ir drops and inductance. a poor layout increases voltage drops, conse- quently affecting efficiency. use large traces for the power supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance. proper grounding guidelines help to improve audio performance, minimize crosstalk between channels, and prevent switching noise from coupling into the audio signal. to maintain high output swing and high peak output power, the pcb traces that connect the output pins to the load, as well as the pcb traces to the supply pins, should be as wide as possible to maintain the minimum trace resistances. it is also recommended that a large ground plane be used for minimum impedances. in addition, good pcb layout isolates critical analog paths from sources of high interference. high frequency circuits (analog and digital) should be separated from low frequency circuits. properly designed multilayer pcbs can reduce emi emissions and increase immunity to the rf field by a factor of 10 or more, compared with double-sided boards. a multilayer board allows a complete layer to be used for the ground plane, whereas the ground plane side of a double-sided board is often disrupted by signal crossover. if the system has separate analog and digital ground and power planes, the analog ground plane should be directly beneath the analog power plane, and, similarly, the digital ground plane should be directly beneath the digital power plane. there should be no overlap between the analog and digital ground planes or between the analog and digital power planes. input capacitor selection the ssm2377 does not require input coupling capacitors if the input signal is biased from 1.0 v to v dd ? 1.0 v. input capacitors are required if the input signal is not biased within this recom- mended input dc common-mode voltage range, if high-pass filtering is needed, or if a single-ended source is used. if high- pass filtering is needed at the input, the input capacitor (c in ) and the input impedance of the ssm2377 form a high-pass filter with a corner frequency determined by the following equation: f c = 1/(2 80 k c in ) the input capacitor value and the dielectric material can significantly affect the performance of the circuit. not using input capacitors can generate a large dc output offset voltage and degrade the dc psrr performance. power supply decoupling to ensure high efficiency, low total harmonic distortion (thd), and high psrr, proper power supply decoupling is necessary. noise transients on the power supply lines are short-duration voltage spikes. these spikes can contain frequency components that extend into the hundreds of megahertz. the power supply input must be decoupled with a good quality, low esl, low esr capacitor, with a minimum value of 4.7 f. this capacitor bypasses low frequency noises to the ground plane. for high frequency transient noises, use a 0.1 f capacitor as close as possible to the vdd pins of the device. placing the decoupling capacitors as close as possible to the ssm2377 helps to maintain efficient performance.
ssm2377 rev. 0 | page 15 of 16 outline dimensions 09-23-2010-a a b c 0.645 0.600 0.555 1.280 1.240 sq 1.200 1 2 3 bottom view (ball side up) top view (ball side down) end view 0.300 0.260 0.220 0.80 ref 0.80 ref 0.40 ref 0.415 0.400 0.385 seating plane 0.230 0.200 0.170 coplanarity 0.05 ball a1 identifier figure 37. 9-ball wafer level chip scale package [wlcsp] (cb-9-4) dimensions shown in millimeters ordering guide model 1 temperature range package description package option 2 branding ssm2377acbz-rl ?40c to +85c 9-ball wafer level chip scale package [wlcsp] cb-9-4 y48 ssm2377acbz-r7 ?40c to +85c 9-ball wafer level chip scale package [wlcsp] cb-9-4 y48 EVAL-SSM2377Z evaluation board 1 z = rohs compliant part. 2 this package option is halide free.
ssm2377 rev. 0 | page 16 of 16 notes ?2011 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d09824-0-5 /11(0)

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