View LTC3370-15_8181840.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

1 for more information www.linear.com/ltc3370 typical a pplica t ion fea t ures descrip t ion 4-channel 8a configurable buck dc/dcs the lt c ? 3370 is a highly flexible multioutput power supply ic . the device includes four synchronous buck converters, configured to share eight 1 a power stages, each of which is powered from independent 2.25 v to 5.5v inputs. the dc/dcs are assigned to one of eight power configu - rations via pin programmable c1-c3 pins. the common buck switching frequency may be programmed with an external resistor, synchronized to an external oscillator, or set to a default internal 2mhz clock. the operating mode for all dc/dcs may be programmed via the pll/ mode pin for burst mode or forced continuous mode operation. a pgoodall output indicates when all enabled dc/dcs are within a specified percentage of their final output value. to reduce input noise, the buck converters are phased in 90 steps. precision enable pin thresholds facilitate reliable power -up sequencing. the ltc3370 is available in a 32-lead 5mm 5mm qfn package. a pplica t ions n 8 1 a power stages configurable as 2, 3, or 4 output channels n 8 unique output configurations (1 a to 4 a per channel) n independent v in supplies for each dc/dc (2.25v to 5.5 v) n low total no load supply current: n zero current in shutdown ( all channels off) n 63 a one channel active in burst mode ? operation n 18 a per additional channel n precision enable pin thresholds for autonomous sequencing n 1mhz to 3mhz rt programmable frequency (2mhz default) or pll synchronization n temp monitor indicates die temperature n pgoodall pin indicates all enabled bucks are in regulation n 32-lead 5mm 5mm qfn package n general purpose multichannel power supplies: automotive, industrial, distributed power systems l, lt , lt c , lt m , linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. buck efficiency vs i load c3 c2 c1 buck1 buck2 buck3 buck4 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 2 a 3a 3a 4a 3a 4a 4a 4a 2 a 1a 1a 1a 2a C C C 2 a 2a 1a 1a C 2a 1a C 2 a 2a 3a 2a 3a 2a 3a 4a 2.25v to 5.5v v ina v inb v ine v inf v inc v ind v ing v inh swa swb swe swf 2.25v to 5.5v v out1 1.2v/2a v out3 1.8v/2a v out4 2.5v/2a v out2 1.5v/2a 324k 649k 402k 715k 649k 806k 649k 665k 309k 2.7v to 5.5v ltc3370 v cc c1 c2 c3 fb2 en2 fb1 en1 2.5v to 5.5v swc swd swg swh 2.25v to 5.5v 2.2h 2.2h 2.2h 2.2h fb4 en4 fb2 en2 temp pgoodall pll/mode rt 3370 ta01a gnd 20 30 40 50 60 70 80 90 100 efficiency (%) 3370 ta01b 1a buck 2a buck 3a buck 4a buck v in = 3.3v v out = 1.8v f osc = 1mhz l = 3.3h burst mode operation ltc 3370 3370f load current (ma) 1 10 100 1000 4000 0 10
2 for more information www.linear.com/ltc3370 table o f c on t en t s features ............................................................................................................................ 1 applications ....................................................................................................................... 1 t ypical application ............................................................................................................... 1 description ......................................................................................................................... 1 absolute maximum ratings ..................................................................................................... 3 order information ................................................................................................................. 3 pin configuration ................................................................................................................. 3 electrical characteristics ........................................................................................................ 4 t ypical performance characteristics .......................................................................................... 6 pin functions ..................................................................................................................... 12 block diagram .................................................................................................................... 14 operation ..........................................................................................................................15 buck switching regulators ............................................................................................................................... ..... 15 buck regulators with combined power stages ..................................................................................................... 15 p ower failure reporting via pgoodall pin ......................................................................................................... 16 t emperature monitoring and overtemperature protection ..................................................................................... 16 pr ogramming the operating frequency ................................................................................................................. 16 applications information ....................................................................................................... 17 b uck switching regulator output voltage and feedback network ........................................................................ 17 bu ck regulators ............................................................................................................................... ..................... 17 combined buck power stages ............................................................................................................................... 17 i nput and output decoupling capacitor selection.................................................................................................. 17 pcb considerations ............................................................................................................................... ................ 19 typical applications ............................................................................................................. 20 package description ............................................................................................................ 23 t ypical application .............................................................................................................. 24 related parts ..................................................................................................................... 24 ltc 3370 3370f
3 for more information www.linear.com/ltc3370 p in c on f igura t ion a bsolu t e maxi m u m r a t ings v ina -h , fb 1-4, en 1-4, v cc , pgoodall , rt, pll / mode , c 1-3 ................................... C0. 3 v to 6v temp .................. C 0.3 v to lesser of (v cc + 0.3 v) or 6v i pgoodall ................................................................. 5 ma op erating junction temperature range ( notes 2, 3) ............................................ C 40 c to 150 c storage temperature range .................. C 65 c to 150 c (note 1) o r d er i n f or m a t ion lead free finish tape and reel part marking* package description temperature range ltc3370euh#pbf ltc3370euh#trpbf 3370 32-lead (5mm 5mm) plastic qfn C40c to 125c ltc3370iuh#pbf ltc3370iuh#trpbf 3370 32-lead (5mm 5mm) plastic qfn C40c to 125c ltc3370huh#pbf ltc3370huh#trpbf 3370 32-lead (5mm 5mm) plastic qfn C40c to 150c consult lt c marketing for parts specified with wider operating temperature ranges. *the temperature grade is identified by a label on the shipping container. consult lt c marketing for information on nonstandard lead based finish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 32 31 30 29 28 27 26 25 9 10 11 12 top view 33 gnd uh package 32-lead (5mm 5mm) plastic qfn 13 14 15 16 17 18 19 20 21 22 23 24 8 7 6 5 4 3 2 1v ina swa swb v inb v inc swc swd v ind v inh swh swg v ing v inf swf swe v ine fb1 en1 temp v cc pll/mode rt en4 fb4 fb2 en2 c1 c2 c3 pgoodall en3 fb3 t jmax = 125c, ja = 34c/w, jc = 3c/w exposed pad ( pin 33) is gnd, must be soldered to pcb ltc 3370 3370f
4 for more information www.linear.com/ltc3370 e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at t a = 25c (note 2). v cc = v ina-h = 3.3v, unless otherwise specified. symbol parameter conditions min typ max units v cc v cc voltage range l 2.7 5.5 v v cc(uvlo) undervoltage threshold on v cc v cc voltage falling v cc voltage rising l l 2.325 2.425 2.45 2.55 2.575 2.675 v v i vcc(alloff) v cc input supply current all switching regulators in shutdown 0 2.5 a i vcc v cc input supply current one buck active pll/mode = 0v, r t = 400k, v fb(buck) = 0.85v pll/mode = 2mhz 45 170 70 250 a a f osc internal oscillator frequency v rt = v cc , pll/mode = 0v v rt = v cc , pll/mode = 0v r t = 400k, pll/mode = 0v l l 1.8 1.75 1.8 2 2 2 2.2 2.25 2.2 mhz mhz mhz f pll/mode synchronization frequency t low , t high > 40ns l 1 3 mhz v pll/mode pll/mode level high pll/mode level low for synchronization for synchronization l l 1.2 0.4 v v v rt rt servo voltage r t = 400k l 780 800 820 mv temp monitor v temp(room) temp voltage at 25c 180 220 260 mv v temp /c v temp slope 7 mv/c ot overtemperature shutdown 170 c ot hyst overtemperature hysteresis 10 c 1a buck regulators v in buck input voltage range l 2.25 5.5 v v out buck output voltage range l v fb v in v v in(uvlo) undervoltage threshold on v in v in voltage falling v in voltage rising l l 1.95 2.05 2.05 2.15 2.15 2.25 v v i vin burst mode operation input current forced continuous mode operation input current shutdown input current v fb = 0.85v (note 4) i sw(buck) = 0a, fb = 0v 18 400 0 30 600 2.5 a a a i fwd pmos current limit (note 5) 1.9 2.3 2.7 a v fb1 feedback regulation voltage for buck 1 l 792 800 808 mv v fb feedback regulation voltage for bucks 2-4 l 780 800 820 mv i fb feedback leakage current v fb = 0.85v C50 50 na d max maximum duty cycle v fb = 0v l 100 % r pmos pmos on-resistance i sw = 100ma 300 m r nmos nmos on-resistance i sw = C100ma 240 m i leakp pmos leakage current en = 0 C2 2 a i leakn nmos leakage current en = 0 C2 2 a t ss soft-start time 1 ms v pgood(fall) falling pgood threshold for buck 1 % of regulated v fb 96.8 98 99.2 % falling pgood threshold for bucks 2 to 4 % of regulated v fb 93 95 97 % v pgood(hys) pgood hysteresis for bucks 1 to 4 % of regulated v fb 0.3 % ltc 3370 3370f
5 for more information www.linear.com/ltc3370 e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at t a = 25c (note 2). v cc = v ina-h = 3.3v, unless otherwise specified. symbol parameter conditions min typ max units buck regulators combined i fwd 2 pmos current limit 2 buck power stages combined (note 5) 4.6 a i fwd 3 pmos current limit 3 buck power stages combined (note 5) 6.9 a i fwd 4 pmos current limit 4 buck power stages combined (note 5) 9.2 a interface logic pins (pgoodall, pll/mode, ct, c1, c2, c3) i oh output high leakage current pgoodall 5.5v at pin 1 a v ol output low voltage pgoodall 3ma into pin 0.1 0.4 v v il c1, c2, c3 input low threshold l 0.4 v v ih pll/mode, ct, c1, c2, c3 input high threshold l v cc C 0.4 v v il pll/mode input low threshold l v cc C 1.2 v interface logic pins (en1, en2, en3, en4) v hi(alloff) enable rising threshold all regulators disabled l 730 1200 mv v hi enable rising threshold at least one regulator enabled l 400 420 mv v lo enable falling threshold 340 375 mv i en enable pin leakage current en = 3.3v 1 a note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: the ltc3370 is tested under pulsed load conditions such that t j t a . the ltc3370e is guaranteed to meet specifications from 0c to 85c junction temperature. specifications over the C40c to 125 c operating junction temperature range are assured by design, characterization and correlation with statistical process controls. the ltc3370i is guaranteed over the C40c to 125c operating junction temperature range. the ltc3370h is guaranteed over the C40c to 150c operating junction temperature range. high junction temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than 125c. note that the maximum ambient temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal impedance and other environmental factors. the junction temperature (t j in c) is calculated from the ambient temperature (t a in c) and power dissipation (p d in watts) according to the formula: t j = t a + (p d ? ja ) where ja (in c/w) is the package thermal impedance. note 3: the ltc3370 includes overtemperature protection which protects the device during momentary overload conditions. junction temperatures will exceed 150c when overtemperature protection is active. continuous operation above the specified maximum operating junction temperature may impair device reliability. note 4: static current, switches not switching. actual current may be higher due to gate charge losses at the switching frequency. note 5: the current limit features of this part are intended to protect the ic from short term or intermittent fault conditions. continuous operation above the maximum specified pin current rating may result in device degradation over time. ltc 3370 3370f
6 for more information www.linear.com/ltc3370 typical p er f or m ance c harac t eris t ics buck v in undervoltage threshold vs temperature v cc supply current vs temperature v cc supply current vs temperature r t programmed oscillator frequency vs temperature default oscillator frequency vs temperature buck efficiency vs i load buck power loss vs i load v cc undervoltage threshold vs temperature oscillator frequency vs v cc t a = 25c, unless otherwise noted. load current (ma) efficiency (%) 3370 g01 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 burst mode operation v in = 3.3v v out = 1.8v f osc = 2mhz l = 2.2h 1a buck 2a buck 3a buck 4a buck power loss (mw) 3000 2500 1000 500 2000 1500 0 1 1000 100 10 burst mode operation v in = 3.3v v out = 1.8v f osc = 2mhz l = 2.2h 3370 g02 1a buck 2a buck 3a buck 4a buck load current (ma) v cc (v) 2.7 f osc (mhz) 2.20 2.15 2.00 1.90 2.10 2.05 1.95 1.85 1.80 3.9 5.1 3.5 4.7 3370 g09 5.5 3.1 4.3 v rt = v cc r t = 400k 25 50 75 100 125 i vcc (a) 3370 g05 at least one buck enabled pll/mode = 2mhz temperature (c) 35 65 95 125 155 1.80 1.85 1.90 1.95 2.00 ?55 ?25 5 35 65 95 125 155 0 40 2.05 2.10 2.15 2.20 f osc (mhz) 3371 g07 v cc = 2.7v v cc = 3.3v v cc = 5.5v r t = 400k 80 120 160 200 240 280 320 360 400 i vcc (a) temperature (c) 155 ?55 2.30 ?25 2.35 5 2.40 35 2.45 65 2.50 95 2.55 125 2.60 155 2.65 1.80 2.70 3370 g06 v cc = 2.7v v cc = 3.3v v cc = 5.5v 1.85 uv threshold (v) 1.90 3370 g03 1.95 v cc rising 2.00 v cc falling 2.05 temperature (c) 2.10 ?55 2.15 ?25 2.20 5 f osc (mhz) 35 3370 g08 65 v cc = 2.7v 95 v cc = 3.3v 125 v cc = 5.5v 155 v rt = v cc 1.90 at least one buck enabled 1.95 pll/mode = 0v 2.00 fb = 850mv 2.05 v cc = 2.7v 2.10 v cc = 3.3v 2.15 v cc = 5.5v 2.20 temperature (c) ?55 ?25 5 35 65 95 125 155 0 2.25 2.30 uv threshold (v) ltc 3370 3370 g04 3370f v in rising temperature (c) v in falling ?55 temperature (c) ?25 ?55 ?25 5 5 35 65 95 125
7 for more information www.linear.com/ltc3370 typical p er f or m ance c harac t eris t ics enable pin precision threshold vs temperature enable threshold vs temperature buck v in supply current vs temperature buck v in supply current vs temperature v out vs temperature pmos current limit vs temperature oscillator frequency vs r t v temp vs temperature t a = 25c, unless otherwise noted. r t (k) 250 f osc (mhz) 4.0 3.5 2.0 1.0 3.0 2.5 1.5 0.5 0 450400 3370 g10 350300 500 550 600 650 700 750 800 v cc = 3.3v pmos r ds(on) vs temperature 550 600 650 700 750 800 850 900 en threshold (mv) 3370 g12 en threshold (mv) 3370 g13 155 ?200 0 200 400 600 en rising 800 en falling 1000 temperature (c) 1200 ?55 1400 ?25 5 35 65 95 125 ltc 3370 3370f temperature (c) ?55 ?25 5 35 65 95 125 v temp (mv) 3370 g11 i load = 0ma actual v temp ideal v temp v cc = 3.3v 155 temperature (c) 365 ?55 370 ?25 375 5 380 385 390 395 400 405 35 65 95 125 155 0 10 20 30 40 50 i vin_burst (a) 3370 g14 v in = 2.25v v in = 3.3v v in = 5.5v burst mode operation fb = 850mv temperature (c) ?55 ?25 5 35 65 95 125 155 0 50 100 1.86 1.88 v out (v) 3370 g16 v in = 2.25v v in = 3.3v v in = 5.5v i load = 0ma 150 200 250 300 350 400 450 500 550 i forced continuous mode temperature (c) ?55 ?25 5 35 65 95 125 155 vin_forced_continuous (a) 3370 g15 v in = 2.25v v in = 3.3v v 2.0 2.1 2.2 2.3 2.4 2.5 2.6 i fwd (a) 3370 g17 v in = 3.3v in = 5.5v forced continuous mode fb = 0v temperature (c) ?55 ?25 5 35 65 temperature (c) ?55 ?25 5 35 65 95 125 155 150 95 125 155 1.72 1.74 1.76 1.78 1.80 1.82 1.84 200 250 300 350 400 450 500 550 r ds(on) (m) 3370 g18 v in = 2.25v v in = 3.3v v in = 5.5v en rising en falling all regulators disabled v cc = 3.3v temperature (c) ?55 ?25 5 35 65 95 125 155 350 400 450 500
8 for more information www.linear.com/ltc3370 1a buck power loss vs i load , v out = 1.2v 1a buck efficiency vs i load , v out = 1.8v 1a buck power loss vs i load , v out = 1.8v 1a buck efficiency vs i load , v out = 2.5v 1a buck power loss vs i load , v out = 2.5v 1a buck efficiency vs i load , v out = 3.3v nmos r ds(on) vs temperature 1a buck efficiency vs i load , v out = 1.2v 1a buck power loss vs i load , v out = 3.3v typical p er f or m ance c harac t eris t ics t a = 25c, unless otherwise noted. load current (ma) efficiency (%) 3370 g20 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 1.2v f osc = 2mhz l = 2.2h forced continuous mode v in = 2.25v v in = 3.3v v in = 5.5v v in = 2.25v v in = 3.3v v in = 5.5v burst mode operation load current (ma) efficiency (%) 3370 g22 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 1.8v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 2.25v v in = 3.3v v in = 5.5v v in = 2.25v v in = 3.3v v in = 5.5v load current (ma) power loss (mw) 3370 g23 1000 900 800 400 300 200 100 700 500 600 0 1 1000 100 10 v in = 2.25v burst mode operation v out = 1.8v f osc = 2mhz l = 2.2h v in = 3.3v v in = 5.5v load current (ma) efficiency (%) 3370 g24 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 2.5v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 2.7v v in = 3.3v v in = 5.5v v in = 2.7v v in = 3.3v v in = 5.5v load current (ma) power loss (mw) 3370 g25 1000 900 800 400 300 200 100 700 500 600 0 1 1000 100 10 v in = 2.7v burst mode operation v out = 2.5v f osc = 2mhz l = 2.2h v in = 3.3v v in = 5.5v load current (ma) efficiency (%) 3370 g26 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 3.3v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 4.2v v in = 5.5v v in = 4.2v v in = 5.5v load current (ma) power loss (mw) 3370 g21 1000 900 800 400 300 200 100 700 500 600 0 1 1000 100 10 v in = 2.25v burst mode operation v out = 1.2v f osc = 2mhz l = 2.2h v in = 3.3v v in = 5.5v load current (ma) power loss (mw) 3370 g27 1000 900 800 400 300 200 100 700 500 600 0 1 1000 100 10 burst mode operation v out = 3.3v f osc = 2mhz l = 2.2h v in = 5.5v v in = 4.2v 155 150 200 250 300 350 400 450 r ds(on) (m) 3370 g19 v in = 2.25v v in = 3.3v v in = 5.5v ltc 3370 3370f temperature (c) ?55 ?25 5 35 65 95 125
9 for more information www.linear.com/ltc3370 3a buck efficiency vs i load , v out = 1.8v 3a buck efficiency vs i load , v out = 2.5v 4a buck efficiency vs i load , v out = 1.8v 4a buck efficiency vs i load , v out = 2.5v 1a buck efficiency vs i load (across operating frequency) 1a buck efficiency vs frequency (forced continuous mode) 2a buck efficiency vs i load , v out = 1.8v 2a buck efficiency vs i load , v out = 2.5v typical p er f or m ance c harac t eris t ics t a = 25c, unless otherwise noted. load current (ma) efficiency (%) 3370 g28 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 1.8v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 2.25v v in = 3.3v v in = 5.5v v in = 2.25v v in = 3.3v v in = 5.5v load current (ma) efficiency (%) 3370 g29 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 2.5v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 2.7v v in = 3.3v v in = 5.5v v in = 2.7v v in = 3.3v v in = 5.5v load current (ma) efficiency (%) 3370 g30 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 1.8v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 2.25v v in = 3.3v v in = 5.5v v in = 2.25v v in = 3.3v v in = 5.5v load current (ma) efficiency (%) 3370 g31 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 v out = 2.5v f osc = 2mhz l = 2.2h burst mode operation forced continuous mode v in = 2.7v v in = 3.3v v in = 5.5v v in = 2.7v v in = 3.3v v in = 5.5v load current (ma) efficiency (%) 3370 g32 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 burst mode operation forced continuous mode v in = 2.25v v in = 3.3v v in = 5.5v v in = 2.25v v in = 3.3v v in = 5.5v v out = 1.8v f osc = 2mhz l = 2.2h load current (ma) efficiency (%) 3370 g33 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 burst mode operation forced continuous mode v in = 2.7v v in = 3.3v v in = 5.5v v in = 2.7v v in = 3.3v v in = 5.5v v out = 2.5v f osc = 2mhz l = 2.2h load current (ma) efficiency (%) 3370 g34 100 90 80 40 30 20 10 70 50 60 0 1 1000 100 10 burst mode operation forced continuous mode f osc = 1mhz, l = 3.3h f osc = 2mhz, l = 2.2h f osc = 3mhz, l = 1h f osc = 1mhz, l = 3.3h f osc = 2mhz, l = 2.2h f osc = 3mhz, l = 1h v out = 1.8v v in = 3.3v frequency (mhz) efficiency (%) 3370 g35 100 90 80 40 30 20 10 70 50 60 0 1 3 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 v out = 1.8v i load = 100ma l = 3.3h v in = 3.3v v in = 2.25v v in = 5.5v 1a buck efficiency vs frequency (forced continuous mode) frequency (mhz) efficiency (%) 3370 g36 100 90 80 40 30 20 10 70 50 60 0 1 3 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 v out = 1.8v i load = 200ma l = 3.3h v in = 2.25v v in = 5.5v v in = 3.3v ltc 3370 3370f
10 for more information www.linear.com/ltc3370 4a buck regulator load regulation ( forced continuous mode) 1a buck regulator line regulation ( forced continuous mode) 1a buck regulator no- load start- up transient(burst mode operation) 1a buck regulator no- load start- up transient (forced continuous mode) 4a buck regulator no- load start- up transient (burst mode operation) 4a buck regulator no- load start- up transient (forced continuous mode) 1a buck efficiency vs frequency (forced continuous mode) 1a buck regulator load regulation ( forced continuous mode) 1a buck regulator transient response (burst mode operation) typical p er f or m ance c harac t eris t ics t a = 25c, unless otherwise noted. frequency (mhz) efficiency (%) 3370 g37 100 90 80 40 30 20 10 70 50 60 0 1 3 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 v out = 1.8v v in = 3.3v l = 3.3h i load = 100ma i load = 500ma i load = 20ma load current (ma) v out (v) 3370 g38 1.820 1.816 1.812 1.796 1.792 1.788 1.784 1.808 1.800 1.804 1.780 1 1000 100 10 v in = 5.5v v in = 3.3v v in = 2.25v dropout f osc = 2mhz l = 2.2h load current (ma) v out (v) 3370 g39 1.820 1.816 1.812 1.796 1.792 1.788 1.784 1.808 1.800 1.804 1.780 1 1000 100 10 v in = 3.3v v in = 2.25v f osc = 2mhz l = 2.2h dropout v in = 5.5v v in (v) v out (v) 3370 g40 1.820 1.815 1.795 1.790 1.785 1.810 1.800 1.805 1.780 2.25 2.75 3.25 3.75 4.25 4.75 5.25 f osc = 2mhz l = 2.2h i load = 100ma i load = 500ma 200s/div v out 500mv/div inductor current 500ma/div en 2v/div 3370 g41 v in = 3.3v v out = 1.8v 200s/div v out 500mv/div inductor current 500ma/div en 2v/div 3370 g42 v in = 3.3v v out = 1.8v 200s/div v out 500mv/div inductor current 500ma/div en 2v/div 3370 g43 v in = 3.3v v out = 1.8v 200s/div v out 500mv/div inductor current 500ma/div en 2v/div 3370 g44 v in = 3.3v v out = 1.8v 50s/div v out 100mv/div ac-coupled inductor current 200ma/div 0ma 3370 g45 load step = 100ma to 700ma v in = 3.3v v out = 1.8v ltc 3370 3370f
11 for more information www.linear.com/ltc3370 4a buck regulator transient response (burst mode operation) 4a buck regulator transient response (forced continuous mode) 1a buck regulator transient response (forced continuous mode) typical p er f or m ance c harac t eris t ics t a = 25c, unless otherwise noted. 50s/div v out 100mv/div ac-coupled inductor current 200ma/div 0ma 3370 g46 load step = 100ma to 700ma v in = 3.3v v out = 1.8v 50s/div v out 100mv/div ac-coupled inductor current 1a/div 0ma 3370 g47 load step = 400ma to 2.8a v in = 3.3v v out = 1.8v 50s/div v out 100mv/div ac-coupled inductor current 1a/div 0ma 3370 g48 load step = 400ma to 2.8a v in = 3.3v v out = 1.8v ltc 3370 3370f
12 for more information www.linear.com/ltc3370 p in func t ions v ina (pin 1): power stage a input supply. bypass to gnd with a 10f or larger ceramic capacitor. swa (pin 2): power stage a switch node. external induc - tor connects to this pin. swb ( pin 3): power stage b switch node. external induc- tor connects to this pin. v inb (pin 4): power stage b input supply. bypass to gnd with a 10f or larger ceramic capacitor. v inc (pin 5): power stage c input supply. bypass to gnd with a 10f or larger ceramic capacitor. swc (pin 6): power stage c switch node. external induc - tor connects to this pin. swd ( pin 7): power stage d switch node. external induc- tor connects to this pin. v ind (pin 8): power stage d input supply. bypass to gnd with a 10f or larger ceramic capacitor. fb2 (pin 9): buck regulator 2 feedback pin. receives feedback by a resistor divider connected across the output. in configurations where buck 2 is not used, fb2 should be tied to ground. en2 (pin 10): buck regulator 2 enable input. active high. in configurations where buck 2 is not used, tie en2 to ground. do not float. c1 (pin 11): configuration control input bit. with c2 and c3, c1 configures the buck output current power stage combinations. c1 should either be tied to v cc or ground. do not float. c2 (pin 12): configuration control input bit. with c1 and c3, c2 configures the buck output current power stage combinations. c2 should either be tied to v cc or ground. do not float. c3 (pin 13): configuration control input bit. with c1 and c2, c3 configures the buck output current power stage combinations. c3 should either be tied to v cc or ground. do not float. pgoodall (pin 14): pgood status pin ( active low). open-drain output. when the regulated output voltage of any enabled switching regulator is below its pgood threshold level, this pin is driven low. this level is 98% of the programmed output value for buck 1 and 95% of the programmed output value for bucks 2-4. when all buck regulators are disabled pgoodall is driven low. en3 (pin 15): buck regulator 3 enable input. active high. in configurations where buck 3 is not used, tie en3 to ground. do not float. fb3 (pin 16): buck regulator 3 feedback pin. receives feedback by a resistor divider connected across the output. in configurations where buck 3 is not used, fb3 should be tied to ground. v ine (pin 17): power stage e input supply. bypass to gnd with a 10f or larger ceramic capacitor. swe (pin 18): power stage e switch node. external inductor connects to this pin. swf (pin 19): power stage f switch node. external inductor connects to this pin. v inf (pin 20): power stage f input supply. bypass to gnd with a 10f or larger ceramic capacitor. v ing ( pin 21): power stage g input supply. bypass to gnd with a 10f or larger ceramic capacitor. swg (pin 22): power stage g switch node. external inductor connects to this pin. swh (pin 23): power stage h switch node. external inductor connects to this pin. v inh ( pin 24): power stage h input supply. bypass to gnd with a 10f or larger ceramic capacitor. fb 4 (pin 25): buck regulator 4 feedback pin. receives feedback by a resistor divider connected across the output. en4 (pin 26): buck regulator 4 enable input. active high. do not float. ltc 3370 3370f
13 for more information www.linear.com/ltc3370 p in func t ions rt (pin 27): oscillator frequency pin. this pin provides two modes of setting the switching frequency. connecting a resistor from rt to ground sets the switching frequency based on the resistor value. if rt is tied to v cc the internal 2mhz oscillator is used. do not float. pll/mode (pin 28): oscillator synchronization and buck mode select pin. driving pll/mode with an external clock signal synchronizes all switches to the applied frequency, and the buck converters operate in forced continuous mode. the slope compensation is automatically adapted to the external clock frequency. the absence of an external clock signal enables the frequency programmed by the rt pin. when not synchronizing to an external clock this input determines how the ltc3370 operates at light loads. pulling this pin to ground selects burst mode operation. tying this pin to v cc invokes forced continuous mode operation. do not float. v cc (pin 29): internal bias supply. bypass to gnd with a 10f or larger ceramic capacitor. temp ( pin 30): temperature indication pin. temp outputs a voltage of 220mv ( typical) at 25 c. the temp voltage increases by 7mv/c ( typical) at higher temperatures giving an external indication of the ltc3370 internal die temperature. en 1 (pin 31): buck regulator 1 enable input. active high. do not float. fb1 (pin 32): buck regulator 1 feedback pin. receives feedback by a resistor divider connected across the output. gnd ( exposed pad pin 33): ground. the exposed pad should be connected to a continuous ground plane on the printed circuit board directly under the ltc3370. ltc 3370 3370f
14 for more information www.linear.com/ltc3370 b lock diagra m pgood logic buck regulator 1 control bandgap uvlo sd 4 pgood v inb mode 31 en1 32 fb1 oscillator 27 rt 29 v cc 28 pll/mode 14 pgoodall clk ref ot uv mode buck regulator 2 control v ind 10 fb2 9 en2 buck regulator 3 control v ine 15 fb3 16 en3 buck regulator 4 control 1a power stage h v ing c2 configuration lines 26 en4 25 fb4 sd ref clk 4 12 c1 11 c3 gnd (exposed pad) swh 3370 bd v inh 13 33 23 24 1a power stage g swg v ing 22 21 1a power stage f swf v inf 19 20 1a power stage e swe v ine 18 17 1a power stage d swd v ind 7 8 1a power stage c swc v inc 6 5 1a power stage b swb v inb 3 4 1a power stage a temp monitor swa v ina 2 1 temp 30 4 c3 c2 c1 buck1 buck2 buck3 buck4 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 2 a 3a 3a 4a 3a 4a 4a 4a 2 a 1a 1a 1a 2a C C C 2 a 2a 1a 1a C 2a 1a C 2 a 2a 3a 2a 3a 2a 3a 4a ltc 3370 3370f
15 for more information www.linear.com/ltc3370 o pera t ion buck switching regulators the ltc3370 contains eight monolithic 1a synchronous buck switching channels. these are controlled by up to four current mode regulator controllers. all of the switch - ing regulators are internally compensated and need only external feedback resistors to set the output voltage. the switching regulators offer two operating modes: burst mode operation (pll/mode = low) for higher efficiency at light loads and forced continuous pwm mode (pll/ mode = high or switching) for lower noise at light loads. in burst mode operation at light loads, the output capacitor is charged to a voltage slightly higher than its regulation point. the regulator then goes into a sleep state, during which time the output capacitor provides the load current. in sleep most of the regulators circuitry is powered down, helping conserve input power. when the output capaci - tor droops below its programmed value, the circuitry is powered on and another burst cycle begins. the sleep time decreases as load current increases. in burst mode operation, the regulator bursts at light loads whereas at higher loads it operates at constant frequency pwm mode operation. in forced continuous mode, the oscillator runs continuously and the buck switch currents are allowed to reverse under very light load conditions to maintain regulation. this mode allows the buck to run at a fixed frequency with minimal output ripple. each buck switching regulator can operate at an indepen - dent v in voltage and has its own fb and en pin to maxi- mize flexibility . the enable pins have two different enable threshold voltages that depend on the operating state of the ltc3370. with all regulators disabled, the enable pin threshold is set to 730mv ( typical). once any regulator is enabled, the enable pin thresholds of the remaining regulators are set to a bandgap-based 400 mv and the en pins are each monitored by a precision comparator. this precision en threshold may be used to provide event- based sequencing via feedback from other previously enabled regulators. all buck regulators have forward and reverse-current limiting, soft-start to limit inrush current during start-up, and short-circuit protection. the buck switching regulators are phased in 90 steps to reduce noise and input ripple. the phase step determines the fixed edge of the switching sequence, which is when the pmos turns on. the pmos off ( nmos on) phase is subject to the duty cycle demanded by the regulator . buck ?1 is set to 0, buck 2 is set to 90, buck 3 is set to 270, and buck 4 is set to 180. in shutdown all sw nodes are high impedance. the buck regulator enable pins may be tied to v out voltages through a resistor divider, to program power-up sequencing. the buck switching regulators feature a controlled shut - down scheme where the inductor current ramps down to zero through the nmos switch. if any event causes the buck regulator to shut down (en = low, ot, v ina-h or v cc uvlo) the nmos switch turns on until the inductor current reaches 0ma ( typical). then, the switch pin becomes hi-z. buck regulators with combined power stages up to four adjacent buck regulators may be combined in a master-slave configuration by setting the configuration via the c1, c2, and c3 pins. these pins should either be tied to ground or pin strapped to v cc in accordance with the desired configuration code ( table 1). any combined sw pins must be tied together, as must any of the com - bined v in pins. en1 and fb1 are utilized by buck 1, en2 and fb2 by buck 2, en3 and fb3 by buck 3, and en4 and fb4 by buck 4. if any buck is not used or is not available in the desired configuration, then the associated fb and en pins must be tied to ground. any available combination of 2, 3, or 4 adjacent buck regulators serve to provide up to either 2a, 3 a, or 4a of average output load current. for example, code 110 (c3c2c1) configures buck 1 to operate as a 4 a regula - tor through v in /sw pairs a, b, c, and d, while buck 2 is disabled, buck 3 operates as a 1 a regulator through v in /sw pair e, and buck 4 operates as a 3 a regulator through v in /sw pairs f, g, and h. ltc 3370 3370f
16 for more information www.linear.com/ltc3370 o pera t ion table 1. master slave program combinations (each letter corresponds to a v in and sw pair) program code c3c2c1 buck 1 buck 2 buck 3 buck 4 000 ab cd ef gh 001 abc d ef gh 010 abc d e fgh 011 abch d e fg 100 abc de not used fgh 101 abcd not used ef gh 110 abcd not used e fgh 111 abcd not used not used efgh power failure reporting via pgoodall pin power failure conditions are reported back by the pgoodall pin. each buck switching regulator has an internal power good ( pgood) signal. when the regulated output voltage of an enabled switcher falls below 98% for buck regulator 1 or 95% for buck regulators 2-4 of its programmed value, the pgood signal is pulled low. if any pgood signal stays low for greater than 100 s, then the pgoodall pin is pulled low, indicating to a microprocessor that a power failure fault has occurred. the 100 s filter time prevents the pin from being pulled low due to a transient. the pgood signal has a 0.3% hysteresis such that when the regulated output voltage of an enabled switcher rises above 98.3% or 95.3%, respectively, of its programmed value, the pgood signal transitions high. temperature monitoring and overtemperature protection to prevent thermal damage to the ltc3370 and its sur - rounding components, the ltc3370 incorporates an overtemperature ( ot) function. when the ltc3370 die temperature reaches 170c ( typical) all enabled buck switching regulators are shut down and remain in shutdown until the die temperature falls to 160c (typical). the temperature may be read back by the user by sampling the temp pin analog voltage. the temperature, t , indicated by the temp pin voltage is given by: t = v temp C 45mv 7mv ? 1 c (1) if none of the buck switching regulators are enabled, then the temperature monitor is also shut down to further reduce quiescent current. programming the operating frequency selection of the operating frequency is a trade-off between efficiency and component size. high frequency operation allows the use of smaller inductor and capacitor values. operation at lower frequencies improves efficiency by reducing internal gate charge losses but requires larger inductance values and/or capacitance to maintain low output voltage ripple. the operating frequency for all of the ltc3370 regulators is determined by an external resistor that is connected between the rt pin and ground. the operating frequency can be calculated using the following equation: f osc = 8 ? 10 11 ? ? hz r t (2) while the ltc3370 is designed to function with operat - ing frequencies between 1 mhz and 3 mhz, it has safety clamps that will prevent the oscillator from running faster than 4mhz ( typical) or slower than 250khz ( typical). tying the rt pin to v cc sets the oscillator to the default internal operating frequency of 2mhz (typical). the ltc3370s internal oscillator can be synchronized through an internal pll circuit to an external frequency by applying a square wave clock signal to the pll/mode pin. during synchronization, the top mosfet turn-on of buck regulator 1 is phase locked to the rising edge of the external frequency source. all other buck switching regulators are locked to the appropriate phase of the ex - ternal frequency source ( see buck switching regulators). the synchronization frequency range is 1 mhz to 3mhz. a synchronization signal on the pll/mode pin will force all active buck switching regulators to operate in forced continuous mode pwm . ltc 3370 3370f
17 for more information www.linear.com/ltc3370 a pplica t ions i n f or m a t ion buck switching regulator output voltage and feedback network the output voltage of the buck switching regulators is programmed by a resistor divider connected from the switching regulators output to its feedback pin and is given by v out = v fb (1 + r2/r1) as shown in figure 1. typical values for r1 range from 40 k to 1 m. the buck regulator transient response may improve with optional capacitor, c ff , that helps cancel the pole created by the feedback resistors and the input capacitance of the fb pin. experimentation with capacitor values between 2 pf and 22pf may improve transient response. the c1, c2, and c3 pins ( see table 1). tables 3, 4, and 5 show recommended inductors for the combined power stage configurations. the input supply should be decoupled with a 22 f capacitor while the output should be decoupled with a 47 f capaci - tor for a 2 a combined buck regulator. likewise for 3 a and 4a configurations the input and output capacitance must be scaled up to account for the increased load. refer to the capacitor selection section for details on selecting a proper capacitor. in some cases it may be beneficial to use more power stages than needed to achieve increased efficiency of the active regulators . in general the efficiency will improve by adding stages for any regulator running close to what the rated load current would be without the additional stage. for example, if the application requires a 1 a regulator that supplies close to 1 a at a high duty cycle, a 3 a regulator that only peaks at 3 a but averages a lower current, and a 2 a regulator that runs at 1.5 a at a high duty cycle, bet - ter efficiency may be achieved by using the 3a, 3a, 2a configuration. input and output decoupling capacitor selection the ltc3370 has individual input supply pins for each buck power stage and a separate v cc pin that supplies power to all top level control and logic. each of these pins must be decoupled with low esr capacitors to gnd. these capacitors must be placed as close to the pins as possible. ceramic dielectric capacitors are a good compro - mise between high dielectric constant and stability versus temperature and dc bias. note that the capacitance of a capacitor deteriorates at higher dc bias. it is important to consult manufacturer data sheets and obtain the true capacitance of a capacitor at the dc bias voltage that it will be operated at. for this reason, avoid the use of y5v dielectric capacitors. the x5r/x7r dielectric capacitors offer good overall performance. the input supply voltage pins 1, 4, 5, 8, 17, 20, 21, 24 and 29 all need to be decoupled with at least 10 f capacitors. if power stages are combined the supplies should be shorted with as short of a trace as possible, and the decoupling capacitor should be scaled accordingly. + buck switching regulator v out fb r1 3370 f01 r2 c ff optional c out figure 1. feedback components buck regulators all four buck regulators are designed to be used with inductors ranging from 1 h to 3.3 h depending on the lowest switching frequency at which the buck regulator must operate. when operating at 1 mhz a 3.3 h inductor should be used, while at 3 mhz a 1 h inductor may be used, or a higher value inductor may be used if reduced current ripple is desired. table 2 shows some recom - mended inductors for the buck regulators. the bucks are compensated to operate across the range of possible v in and v out voltages when the appropriate inductance is used for the desired switching frequency. the input supply should be decoupled with a 10 f capacitor while the output should be decoupled with a 22 f capaci - tor. refer to the capacitor selection section for details on selecting a proper capacitor. combined buck power stages the ltc3370 has eight power stages that can handle aver - age load currents of 1 a each. these power stages may be combined in any one of eight possible combinations, via ltc 3370 3370f
18 for more information www.linear.com/ltc3370 a pplica t ions i n f or m a t ion table 2. recommended inductors for 1a buck regulators part number l (h) max i dc (a) max dcr (m) size in mm (l w h) manufacturer ihlp1212aber1r0m-11 1.0 3 38 3 3.6 1.2 vishay 1239as-h-1r0n 1 2.5 65 2.5 2.0 1.2 toko xfl4020-222me 2.2 3.5 23.5 4 4 2.1 coilcraft 1277as-h-2r2n 2.2 2.6 84 3.2 2.5 1.2 toko ihlp1212bzer2r2m-11 2.2 3 46 3 3.6 1.2 vishay xfl4020-332me 3.3 2.8 38.3 4 4 2.1 coilcraft ihlp1212bzer3r3m-11 3.3 2.7 61 3 3.6 1.2 vishay table 3. recommended inductors for 2a buck regulators part number l (h) max i dc (a) max dcr (m) size in mm (l w h) manufacturer xfl4020-102me 1.0 5.1 11.9 4 4 2.1 coilcraft 74437324010 1 5 27 4.45 4.06 1.8 wrth elektronik xal4020-222me 2.2 5.6 38.7 4 4 2.1 coilcraft fdv0530-2r2m 2.2 5.3 15.5 6.2 5.8 3 toko ihlp2020bzer2r2m-11 2.2 5 37.7 5.49 5.18 2 vishay xal4030-332me 3.3 5.5 28.6 4 4 3.1 coilcraft fdv0530-3r3m 3.3 4.1 34.1 6.2 5.8 3 toko table 4. recommended inductors for 3a buck regulators part number l (h) max i dc (a) max dcr (m) size in mm (l w h) manufacturer xal4020-102me 1.0 8.7 14.6 4 4 2.1 coilcraft fdv0530-1r0m 1 8.4 11.2 6.2 5.8 3 toko xal5030-222me 2.2 9.2 14.5 5.28 5.48 3.1 coilcraft ihlp2525czer2r2m-01 2.2 8 20 6.86 6.47 3 vishay 74437346022 2.2 6.5 20 7.3 6.6 2.8 wrth elektronik xal5030-332me 3.3 8.7 23.3 5.28 5.48 3.1 coilcraft spm6530t-3r3m 3.3 7.3 27 7.1 6.5 3 tdk table 5. recommended inductors for 4a buck regulators part number l (h) max i dc (a) max dcr (m) size in mm (l w h) manufacturer xal5030-122me 1.2 12.5 9.4 5.28 5.48 3.1 coilcraft spm6530t-1r0m120 1 14.1 7.81 7.1 6.5 3 tdk xal5030-222me 2.2 9.2 14.5 5.28 5.48 3.1 coilcraft spm6530t-2r2m 2.2 8.4 19 7.1 6.5 3 tdk ihlp2525ezer2r2m-01 2.2 13.6 20.9 6.86 6.47 5 vishay xal6030-332me 3.3 8 20.81 6.36 6.56 3.1 coilcraft fdve1040-3r3m 3.3 9.8 10.1 11.2 10 4 toko ltc 3370 3370f
19 for more information www.linear.com/ltc3370 a pplica t ions i n f or m a t ion pcb considerations when laying out the printed circuit board, the following list should be followed to ensure proper operation of the ltc3370: 1. the exposed pad of the package ( pin 33) should connect directly to a large ground plane to minimize thermal and electrical impedance. 2. each of the input supply pins should have a decoupling capacitor. 3. the connections to the switching regulator input supply pins and their respective decoupling capacitors should be kept as short as possible. the gnd side of these capacitors should connect directly to the ground plane of the part. these capacitors provide the ac current to the internal power mosfets and their drivers. it is important to minimize inductance from these capacitors to the v in pins of the ltc3370. 4. the switching power traces connecting swa , swb, swc, swd, swe, swf, swg, and swh to the induc - tors should be minimized to reduce radiated emi and parasitic coupling. due to the large voltage swing of the switching nodes, high input impedance sensitive nodes, such as the feedback nodes, should be kept far away or shielded from the switching nodes or poor performance could result. 5. the gnd side of the switching regulator output capaci - tors should connect directly to the thermal ground plane of the part. minimize the trace length from the output capacitor to the inductor(s)/pin(s). 6. in a multiple power stage buck regulator application the trace length of switch nodes to the inductor must be kept equal to ensure proper operation. 7. care should be taken to minimize capacitance on the temp pin. if the temp voltage must drive more than ~30pf, then the pin should be isolated with a resistor placed close to the pin of a value between 10 k and 100k. keep in mind that any load on the isolation resistor will create a proportional error. ltc 3370 3370f
20 for more information www.linear.com/ltc3370 typical a pplica t ions 4 2a quad buck application ltc3370 exposed pad 2.2h v ina v inb swa swb fb1 v ing v inh swg swh fb4 v inc v ind swc swd fb2 v ine v inf swe swf fb3 3370 ta02 2.2h 806k 649k 232k 464k 22f 2.25v to 5.5v 1.8v 2a 1.2v 2a 47f 47f 22f 2.25v to 5.5v 402k rt en1 en2 en3 en4 pll/mode c1 c2 c3 v cc pgoodall temp microprocessor control 2.7v to 5.5v microprocessor control 10f 2.2h 2.2h 511k 162k 665k 309k 22f 2.5v to 5.5v 3.3v 2a 2.5v 2a 47f 47f 22f 3.3v to 5.5v ltc 3370 3370f
21 for more information www.linear.com/ltc3370 typical a pplica t ions buck regulators with sequenced start-up driven from a high voltage upstream buck converter exposed pad 2.2h v inh v ina v inb v inc swh swa swb swc fb1 v inf v ing swf swg fb4 3370 ta03 2.2h 806k 649k 232k 1m 464k 47f 1.2v 4a 2.5v 1a 1.8v 2a 10f 10f 22f 22f 3.3v 1a 47f 22f 100f 2.2h ltc3370 v ind swd fb2 v ine swe fb3 2.2h 511k 162k 665k 309k 402k rt en1 en2 en3 en4 pll/mode c1 c2 c3 v cc pgoodall temp v cc microprocessor control 10f 0.1f c in 22f v in 5.5v to 36v intv cc 34.8k 470pf 100k 100k c out : sanyo 10tpe330m d1: dfls1100 l1 coilcraft ser1360-802kl mtop, mbot: si7850dp 19.1k 2.2f d1 0.1f freq ith sgnd sgnd ltc3891 v in pgood pllin/mode i lim intv cc pgnd l1 8h r sense 7m boost sw bg sense + sense ? extv cc v fb tg mtop mbot 1nf c out 330f 5v 6a track/ss run v in en kill int pb tmr gnd on ltc2955ts8-1 microprocessor control microprocessor control ltc 3370 3370f
22 for more information www.linear.com/ltc3370 typical a pplica t ions combined buck regulators with common input supply ltc3370 exposed pad 2.2h v ina swa swb swc swd fb1 v inh swh swg swf fb4 3370 ta04 2.2h 511k 511k 324k 649k 1.6v 3a 1.2v 4a 2.7v to 5.5v 100f 68f 10f 10f 10f 10f 10f 10f 10f 10f v inb v ing v inc v inf 2.2h v ind rt fb2 en2 c1 c2 c3 en1 en3 en4 pll/mode v ine swe fb3 pgoodall temp v cc microprocessor control 665k 309k 2.5v 1a 22f 10f microprocessor control ltc 3370 3370f
23 for more information www.linear.com/ltc3370 information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. p ackage descrip t ion please refer to http://www .linear.com/designtools/packaging/ for the most recent package drawings. 5.00 0.10 (4 sides) note: 1. drawing proposed to be a jedec package outline m0-220 variation whhd-(x) (to be approved) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.20mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package pin 1 top mark (note 6) 0.40 0.10 31 1 2 32 bottom view?exposed pad 3.50 ref (4-sides) 3.45 0.10 3.45 0.10 0.75 0.05 r = 0.115 typ 0.25 0.05 (uh32) qfn 0406 rev d 0.50 bsc 0.200 ref 0.00 ? 0.05 0.70 0.05 3.50 ref (4 sides) 4.10 0.05 5.50 0.05 0.25 0.05 package outline 0.50 bsc recommended solder pad layout apply solder mask to areas that are not soldered pin 1 notch r = 0.30 typ or 0.35 45 chamfer r = 0.05 typ 3.45 0.05 3.45 0.05 uh package 32-lead plastic qfn (5mm 5mm) (reference ltc dwg # 05-08-1693 rev d) ltc 3370 3370f
24 for more information www.linear.com/ltc3370 ? linear technology corporation 2015 lt 0215 ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/ltc3370 r ela t e d p ar t s typical a pplica t ion combined bucks with 3mhz switching frequency and sequenced power up part number description comments ltc3589 8-output regulator with sequencing and i 2 c triple i 2 c adjustable high efficiency step-down dc/dc converters: 1.6a, 1a, 1a. high efficiency 1.2a buck-boost dc/dc converter, triple 250ma ldo regulators. pushbutton on/off control with system reset, flexible pin-strap sequencing operation. i 2 c and independent enable control pins, dynamic voltage scaling and slew rate control. selectable 2.25mhz or 1.12mhz switching frequency, 8a standby current, 40-lead (6mm 6mm 0.75mm) qfn. ltc3675 7-channel configurable high power pmic quad synchronous buck regulators (1a, 1a, 500ma, 500ma). buck dc/dcs can be paralleled to deliver up to 2 current with a single inductor. 1a boost, 1a buck- boost, 40v led driver. 44-lead (4mm 7mm 0.75mm) qfn package. ltc3676 8-channel power management solution for application processor quad synchronous buck regulators (2.5a, 2.5a, 1.5a, 1.5a). quad ldo regulators (300ma, 300ma, 300ma, 25ma). pushbutton on/off control with system reset. ddr solution with vtt and vttr reference. 40-lead (6mm 6mm 0.75mm) qfn package. ltc3375 ltc3374 8- channel programmable configurable 1a dc/dc 8 1a synchronous buck regulators. can connect up to four power stages in parallel to make a single inductor, high current output (4a maximum), 15 output configurations possible, 48-lead (7mm 7mm 0.75mm) qfn package (ltc3375) 38-lead (5mm 7mm 0.75mm) qfn and tssop packages (ltc3374). ltc3371 4-channel configurable dc/dc with 8 1a power stages 4 synchronous buck regulators with 8 1a power stages. can connect up to four power stages in parallel to make a single inductor, high current output (4a maximum), 8 output configurations possible, precision rst monitoring with windowed watchdog timer (ct programmable), 38-lead (5mm 7mm 0.75mm) qfn and tssop packages. ltc3370 exposed pad 1h swa swb swc fb1 v inc v inb v ina v ing v inh swh swg fb4 3370 ta05 1h 649k 432k 324k 649k 2v 2a 2.25v to 5.5v 2.5v to 5.5v 1.2v 3a 2.25v to 5.5v 68f 10f 10f 10f 10f 10f 47f 1h c1 c2 c3 temp pll/mode en1 en2 en3 en4 swe swf fb3 pgoodall swd v ind v ine v inf fb2 511k 162k rt v cc v cc microprocessor control 1h 665k 309k 2.7v to 5.5v 47f 10f 10f 22f 10f 10f 2.5v 2a 3.3v 1a 3.3v to 5.5v 267k microprocessor control ltc 3370 3370f

▲Up To Search▲

Price & Availability of LTC3370-15

	To Download LTC3370-15 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .