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product structure silicon monolithic integrated circuit this product has no designed protection against radioactive ra ys 1/ 26 www.rohm.com ? 20 15 rohm co., ltd. all rights reserved. tsz22111 14 001 tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 0.95v to v cc -1v, 0.5a/1.0a/2.0a 1ch ultra low dropout linear regulators bd3550hfn bd3551hfn bd3552hfn general description bd3550hfn, bd3551hfn and bd3552hfn are ultra low -dropout linear chipset regulators that operate from a very low input supply. the y offer ideal performance in low input voltage to low output voltage applications . the input- to -output voltage difference is minimized by using a built-in n-channel power mosfet with a maximum on-resistance of r on =100m (typ) . by lowering the dropout voltage, the regulator realizes high output current (i outmax =2.0a ) thereby, reducing conversion loss, making it comparable to a switching regulator and its power transistor, choke coil, and rectifier diode constituents. the bd3550hfn, bd3551hfn, bd3552hfn are available in significantly downsized package profiles and allow low-cost design. an external resistor allows the entire range of output voltage configurations between 0.65v and 2.7v, while th e nrcs (soft start) function enables a controlled output voltage ramp-up, which can be programmed to a required power supply sequence. features ? internal high-precision reference voltage circuit (0.65v1%) ? built-in vcc undervoltage lockout circuit ? nrcs (soft start) function reduces the magnitude of in-rush current ? internal n-channel mosfet ? built-in current limit circuit ? built-in thermal shutdown (tsd) circuit ? tracking function applications notebook computers, desktop computers, lcd-tv, dvd, digital appliances key specifications ? in input voltage range: 0.95v to v cc -1v ? vcc input voltage range: 4.3v to 5.5v ? output voltage range: 0.65v to 2. 7v ? standby current: 0a (typ) ? operating temperature range: - 10 c to +100c package w(typ) x d(typ) x h(max) lineup maximum output current on -resistance(typ) package v cc =5v 0.5a 400m hson8 bd3550hfn 1.0a 200m bd3551hfn 2.0a 100m bd3552hfn h so n8 2.90mm x 3.00mm x 0.60mm datashee t datashee t downloaded from: http:///
2/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical application circuit, block diagram pin descriptions pin no. pin name pin function 1 vcc power supply pin 2 en enable input pin 3 gate gate pin 4 in input voltage pin 5 out output voltage pin 6 fb reference voltage feedback pin 7 nrcs in -rush current protection (nrcs) capacitor connection pin 8 gnd ground pin reverse fin connected to heatsink and gnd reference block thermal shutdown nrcs current limit cl uvlo tsd en vcc uvlo vcc cl en vcc vcc in out fb gate gnd nrcs out in tsd downloaded from: http:///
3/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 description of blocks 1. amp this is an error amp that compares the reference voltage ( 0.65v) with fb voltage to drive the output n-channel fet . frequency optimization aids in attaining rapid transient res ponse, and to support the use of ceramic capacitors on th e output. amp output voltage ranges from gnd to vcc. when en is off, or when uvlo is active, output goes low and the output of the n-ch an nel fet switches off. 2. en the en block controls the on and off state of the regulator via the en logic input pin. during off state, circuit voltage stabilizes at 0a which minimizes the current c onsumption during standby mode. the fet is switched on to ena ble discharge of the nrcs and out, thereby draining the exce ss charge and preventing the load side of an ic from malfunctioning. since there is no electrical connectio n required (e.g., between the v cc pin and the esd prevention diode), module operation is independent of the input se quence. 3. uvlo to prevent malfunctions that can occur during a sudden d ecrease in v cc , the uvlo circuit switches the output off, and (like the en block) discharges nrcs and out. once the uvlo threshold voltage (typ3.80v) is reached, the power-on reset is triggered and output is restored. 4. current limit during on state, the current limit function monitors the output current of the ic against the current limit value (2.0a or more: bd3552hfn). when output current exceeds this value , this block lowers the output current to protect the load ic. when it overcomes the over-current state, output voltage i s restored to the normal value. 5. nrcs (non rush current on start- up) the soft start function is enabled by connecting an external capacitor between the nrcs pin and gnd. output ramp-up can be set for any period up to the time the nrcs pin reaches v fb (0.65v). during startup, the nrcs pin serves as a 20 a (typ) constant current source to charge the external capaci tor. output start time is ca lculated by formula (1) below. tracking sequence is possible by connecting the nrcs ou tput to an external power supply instead of external capacitor. and then, ratio-metric sequence is also availa ble by changing the resistor divi der ratio of external power supply voltage. (see page 16) 6. tsd (thermal shut down) the shutdown (tsd) circuit automatically latched off when th e chip temperature exceeds the threshold temperature after the programmed time period elapses, thus protecting the ic against thermal runaway and heat damage. since the tsd circuit is designed only to shut down the ic in the occurrence of extreme heat, it is important that the tj (ma x) parameter should not be exceeded in the thermal design, in ord er to avoid potential problems with the tsd. 7. in the in line acts as the major current supply line, and is connecte d to the output n-channel fet drain. since there is no electrical connection (such as between the vcc pin and the esd protecti on di ode ) required , in operates independent of the input sequence. however, since an output n-channel fet body diode exists between in and out, a v in -v out electric (diode) connection is present. therefore, when output is s witched on or off, reverse current may flow from in to out. ??? (1) a v c t ? 20 65 .0 ? downloaded from: http:///
4/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 absolute maximum ratings (ta=25c) parameter symbol limit unit bd3550hfn bd3551hfn bd3552hfn input voltage 1 v cc +6.0 (note 1) v input voltage 2 v in +6.0 (note 1) v enable input voltage v en -0.3 to +6.0 v power dissipation 1 pd 1 0.63 (note 2) w power dissipation 2 pd 2 1.35 (note 3) w power dissipation 3 pd 3 1.75 (note 4) w operating temperature range topr - 10 to +100 c storage temperature range tstg - 55 to +150 c maximum junction temperature tjmax +150 c (note 1) should not exceed pd. (note 2) derate by 5.04mw/ c for ta above 25 c (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 1-layer) on less than 0.2% (percentage occupied by copper foil. (note 3) derate by 10.8mw/ c for ta above 25 c (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 1-layer) on less than 7.0% (percentage occupied by copper foil. (note 4) derate by 14.0mw/ c for ta bove 25 c (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board, 1-layer) on less than 65.0% (percentage occupied by copper foil. caution: operating the ic over the absolute maximum ratings may damage t he ic. the damage can either be a short circuit between pins or an open circuit between pins and the internal circuitry. therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the ic is operated over the absolute maximum ratings. recommended operating condition s (ta=25 c ) parameter symbol min max unit input voltage 1 v cc 4.3 5.5 v input voltage 2 v in 0.95 v cc - 1 (note 5) v output voltage setting range v out v fb 2.7 v enable input voltage v en 0 5.5 v nrcs capacity c nrcs 0.001 1 f (note 5) vcc and in do not have to be implemented in the order listed. electrical characteristics (unless otherwise specified, ta=25 c , v cc =5v, v en =3v, v in =1.8v, r 1 =3.9k, r 2 =3.3k) parameter sym bol limit unit conditions min typ max bias current i cc - 0.5 1.0 ma vcc shutdown mode current i st - 0 10 a v en =0v output voltage temperature coefficient tcvo - 0.01 - %/c feedback voltage 1 v fb1 0.643 0.650 0.657 v feedback voltage 2 v fb2 0.637 0.650 0.663 v tj=-10c to +100c load regulation reg.l - 0.5 10 mv i out =0a to 1a (bd3550hfn i out =0a to 0.5a) line regulation 1 reg.l1 - 0.1 0.5 %/v v cc =4.3v to 5.5v line regulation 2 reg.l2 - 0.1 0.5 %/v v in =1.2v to 3.3v standby discharge current i den 1 - - ma v en =0v, v out =1v [enable] enable pin input voltage high v enhi 2 - - v enable pin input voltage low v enlow 0 - 0.8 v enable input bias current i en - 7 10 a v en =3v [feedback] feedback pin bias current i fb - 100 0 + 100 na [nrcs] nrcs charge current i nrcs 14 20 26 a v nrcs =0.5v nrcs standby voltage v stb - 0 50 mv v en =0v downloaded from: http:///
5/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 electrical characteristics - continued (unless otherwise specified, ta=25 c , v cc =5v, v en =3v, v in =1.8v, r 1 =3.9k, r 2 =3.3k) parameter symbol limit unit conditions min typ max [uvlo] vcc undervoltage lockout threshold voltage v cc uvlo 3.5 3.8 4.1 v v cc : sweep- up vcc undervoltage lockout hysteresis voltage v cchys 100 160 220 mv v cc : sweep-down [amp] gate source current i gso - 1.6 - ma v fb =0, v gate =2.5v gate sink current i gsi - 4.7 - ma v fb =v cc , v gate =2.5v maximum output current bd3550hfn i out 0.5 - - a bd3551hfn i out 1.0 - - a bd3552hfn i out 2.0 - - a minimum dropout voltage bd3550hfn dv out - 2 00 300 mv i out =0.5a, v in =1.2v, ta=-10c to +100c bd3551hfn dv out - 200 300 mv i out =1.0a, v in =1.2v, ta=-10c to +100c bd3552hfn dv out - 200 300 mv i out =2.0a, v in =1.2v, ta=-10c to +100c downloaded from: http:///
6/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms bd3550hfn 26mv 0.5a v out 50mv/div i out 0.5a/div i out =0a to 1a/sec t(10sec/div) 40mv 0.5a v out 50mv/div i out 0.5a/div i out =0a to 1a/sec t(10sec/div) v out 50mv/div i out 0.5a/div 14mv 0.5a i out =1a to 0a/sec t(100sec/div) figure 1. transient response (0a to 0.5a) c out =100f, c fb =1000pf figure 2. transient response (0a to 0.5a) c out =47f, c fb =1000pf figure 3. transient response (0a to 0.5a) c out =22f, c fb =1000pf figure 4. transient response (0.5 to 0a) c out =100f, c fb =1000pf 22mv 0.5a v out 50mv/div i out 0.5a/div i out =0a to 1a/sec t(10sec/div) downloaded from: http:///
7/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms C continued bd3551hfn 23mv 0.5a i out =1a to 0a/sec t(100sec/div) v out 50mv/div i out 0.5a/div 33mv 0.5a i out =1a to 0a/sec t(100sec/div) v out 50mv/div i out 0.5a/div figure 5. transient response (0.5a to 0a) c out =47f, c fb =1000pf figure 6. transient response (0.5a to 0a) c out =22f, c fb =1000pf 35mv 1.0a v out 50mv/div i out 1.0a/div i out =0a to 1a/sec t(10sec/div) figure 7. transient response (0a to 1.0a) c out =100f, c fb =1000pf 1.0a 46mv v out 50mv/div i out 1.0a/div i out =0a to 1a/sec t(10sec/div) figure 8. transient response (0a to 1.0a) c out =47f, c fb =10 00pf downloaded from: http:///
8/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms C continued 55mv 1.0a v out 50mv/div i out 1.0a/div i out =0a to 1a/sec t(10sec/div) 36mv 1.0a i out = 1a to 0a/sec t(100sec/div) v out 50mv/div i out 1.0a/div i out =0a to 1a/ sec t(10 sec/div) i out =1a to 0a/sec t(100sec/div) 1.0a 46mv v out 50mv/div i out 1.0a/div i out =0a to 1a/ sec t(10 sec/div) i out =1a to 0a/sec t(100sec/div) 56mv 1.0a v out 50mv/div i out 1.0a/div figure 9. transient response (0a to 1.0a) c out =22f, c fb =1000pf figure 10. transient response (1.0a to 0a) c out =100f, c fb =1 000pf figure 12. transient response (1.0a to 0a) c out =22f, c fb =1000pf figure 11. transient response (1.0a to 0a) c out =47f, c fb =10 00pf downloaded from: http:///
9/ 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms C continued bd3552hfn v out 50mv/div i out 2.0a/div i out =0a to 1a/sec t(10sec/div) 26mv 2.0a v out 50mv/div 117mv 2.0a i out =0a to 1a/sec t(10sec/div) i out 2.0a/div v out 50mv/div i out 2.0a/div i out =1a to 0a/sec t(100sec/div) 54mv 2.0a figure 13. transient response (0a to 2.0a) c out =100f, c fb =1000pf figure 14. transient response (0a to 2.0a) c out =47f, c fb =1000pf figure 15. transient response (0a to 2.0a) c out =22f, c fb =1000pf figure 16. transient response (2.0a to 0a) c out =100f, c fb =1000pf i out =0a to 1a/sec t(10sec/div) 89mv 2.0a i out 2.0a/div v out 50mv/div downloaded from: http:///
10 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms C continued bd3551hfn figure 17. transient response (2.0a to 0a) c out =47f, c fb =1000 pf figure 18. transient response (2.0a to 0a) c out =22f, c fb =1 000pf i out =1a to 0a/sec t(100sec/div) 83mv 2.0a v out 50mv/div i out 2.0a/div i out = 1a to 0a/sec t(100sec/div) 117mv 2.0a v out 50mv/div i out 2.0a/div figure 19. waveform at output start figure 20. waveform at output off v nrcs 2v/div v out 1v/div v en 2v/div t(200 sec/div) v en 2v/div t(2msec/div) v nrcs 2v/div v out 1v/div downloaded from: http:///
11 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms C continu ed figure 21. input sequence figure 22. input sequence figure 23. input sequence figure 24. input sequence v cc v en v in v out v cc to v in to v en v in to v cc to v en v cc v en v in v out v en to v cc to v in v cc v en v in v out v cc to v en to v in v cc v en v in v out downloaded from: http:///
12 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical waveforms C continued figure 25. input sequence figure 26. in put sequence v cc v en v in v out v in to v en to v cc v en to v in to v cc v cc v en v in v out downloaded from: http:///
13 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 typical performance curves figure 27. output voltage vs temperature (i out =0ma) 1.15 1.17 1.19 1.21 1.23 1.25 -10 10 30 50 70 90 ta( ) vo(v) 100 temperature : ta (c) output voltage : v out (v) figure 28. circuit current vs temperature 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 -10 10 30 50 70 90 ta( ) icc(ma) 100 temperature : ta (c) circuit current : i cc (ma) figure 29. i stb vs temperature 0.0 0.2 0.4 0.6 0.8 1.0 1.2 -60 -30 0 30 60 90 120 150 temperature : ta (c) i stb (a) figure 30. i in vs temperature 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 -10 10 30 50 70 90 100 temperature : ta (c) i in (a) downloaded from: http:///
14 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 ( ) C A 100 figure 31. i instb vs temperature 0 5 10 15 20 25 30 -60 -30 0 30 60 90 120 150 temperature : ta (c) i in stb (a) figure 32. ncr s charge current vs temperature 15 16 17 18 19 20 21 22 23 24 25 -10 10 30 50 70 90 100 temperature : ta (c) nrcs charge current : i ncrs (a) figure 34. en able input bias current vs temperature 0 1 2 3 4 5 6 7 8 9 10 -10 10 30 50 70 90 100 temperature : ta (c) enable input bias current : i en (a) figure 33. feedback pin bias current vs temperature -20 -15 -10 -5 0 5 10 15 20 -10 10 30 50 70 90 temperature : ta (c) feedback pin bias current : i fb (na) downloaded from: http:///
15 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 ( ) C A figure 36. output on-resistance vs input voltage 1 input voltage 1 : v cc (v) output on-resistance : r on (m) figure 35. output on-resistance vs temperature (v cc =5v/v out =1.2v) 90 100 110 120 130 140 150 -10 10 30 50 70 90 100 temperature : ta (c) output on-resistance : r on (m) downloaded from: http:///
16 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 timing chart en on/off vcc on/off tracking sequence in vcc en nrcs out t startup 0.65v(typ) in vcc en nrcs out t hysteresis uvlo startup 0. 65v(typ) 1.8v output 1.2v output (r 1 =3.9k, r 2 =3.3k) tracking sequence 1.8v output 1.2v output ratio-metric sequence nrcs fb out out r 2 r 1 3.3k 1.2v 3.9k dc/dc 1.8v downloaded from: http:///
17 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 application information 1. evaluation board component rating manufacturer product name component rating manufacturer product name u1 - rohm bd355xhfn c 2 22uf kyocera cm32x5r226m10a c 1 1 f murata grm188b11a105kd c 13 1000pf murata grm188b11h102kd c 10 0.01f murata grm188b11h103 kd r 1 3.9k rohm mcr03ezpf3301 r 8 0 - jumper r 2 3.3k rohm mcr03ezpf3901 c 5 22 f kyocera cm32x5r226m10a bd3550hfn,bd3551hfn,bd3552hfn evaluation board schematic bd3550hfn,bd3551hfn,bd3552hfn evaluation board layout (2nd layer and 3rd layer is gnd line.) bd3550hfn,bd3551hfn,bd3552hfn evaluation board standard component list top layer bottom layer silkscreen t p1 gnd u1 bd355xhfn (hson8) 1 2 3 4 8 7 6 5 v cc vcc v cc gnd gnd vo nrcs gnd fb gate v in r 4 r 8 r 1 r 2 c 5 c 6 c 8 c9 r 3 r 7 r 6 r 5 u2 sw1 c 2 c 3 c 7 c 4 c 11 c 12 c 1 en c 10 7 5 6 8 4 3 2 1 gnd_s v o_ s gn d gnd c 13 gnd tp2 vcc jpf2 jpf1 r 9 c 14 2 3 4 5 vin_s u3 gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd downloaded from: http:///
18 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 2. recommended circuit example component recommended value programming notes and precautions r 1 /r 2 3.9k /3.3k ic output voltage can be set with a configuration formula u sing the values for the internal reference output voltage (v fb ) and the output voltage resistors (r 1 , r 2 ). select resistance values that will avoid the impact of the fb current (100n a) . the recommended total resistance value is 10k . c 3 22f to assure output voltage stability, make sure the out pi n and the gnd pins are connected. output capacitors play a role in loop gain p hase compensation and in minimizing output fluctuation during rapid changes in load level. insufficient capacitance may cause oscillation, while high equivalent series res istance (esr) will exacerbate output voltage fluctuation under rapid load change condit ions. while a 22 f ceramic capacitor is recomended, actual stability is highly de pendent on temperature and load conditions. also, note that connecting different types of capa citors in series may result in insufficient total phase compensation, thus causing osc illation. in light of this information, please confirm operation across a variety of temperature and loa d conditions. c 1 / c 2 1f/22f input capacitors reduce the output impedance of the voltage supply source connected to the (vcc, in ) input pins. if the impedance of this power supply were to increase, input voltage (v cc , v in ) could become unstable, leading to oscillation or dec reased ripple rejection ability. while a low-esr 1f/22f capacitor with mi nimal susceptibility to temperature is recommended, stability is highly dependent on the input power supply characteristics and the substrate wiring pattern. in light of this information, please confirm operation across a variety of temperature and load conditions. c 4 0.01f the non rush current on startup (nrcs) function is built into the ic to prevent rush current from going through the load (in to out) and affecting outp ut capacitors at power supply start-up. constant current comes from the nrcs pin when en is high or the uvlo function is deactivated. the temporary reference voltage is proportional to time, due to the current charge of the nrcs pin capacitor, and outp ut voltage start-up is proportional to this reference voltage. capacitors with low s usceptibility to temperature are recommended, in order to ensure a stable soft-start time. c 5 - this component is employed when the c 3 capacitor causes, or may cause, oscillation. it provides more precise internal phase correction. r 4 several k to several 10k it is recommended that a resistance (several k to several 10k) be put in r 4 , in case negative voltage is applied in en pin. 1 2 3 4 8 7 6 5 vo(1.2v) c 3 r 2 r 1 fb c 4 gnd v cc c 1 v en c 2 v in r 4 c 5 downloaded from: http:///
19 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 3. heat loss in thermal design consider the temperature range wherein the ic is guaranteed to operate and apply appropriate margins. the temperature conditions that need to be conside red are listed below: (1) ambient temperature ta can be no higher than 100c. (2) chip junction temperature (tj) can be no higher than 150c. chip junction temperature can be determined as follows: it is recommended to layout the via for heat radiation in the gnd pattern of reverse (of ic) when there is the gnd pattern in the inner layer (in using multiplayer substrate). this package is so small (size: 2.9mm x 3.0mm) that it is not available to layout the via in the bottom of ic. spreading th e pattern and being increased the number of via as shown in the figure below), enable to achieve superior heat radi ation characteristic. (this figure is an image only. it is recommended that the via size and the number is designed sui table for the actual situation.). most of the heat loss in bd3550hfn, bd3551hfn, bd3552hfn occurs at the outp ut n-channel fet. power loss is determined by the total in-out voltage and output current. be s ure to confirm the system input and output voltage and the output current conditions in relation to the heat dissipati on characteristics of the in and out in the design. bearing in mind that heat dissipation may vary substantially dep ending on the substrate employed make sure to factor conditions such as substrate size into the thermal design. power consumption (w) = input voltage (v in )- output voltage (v out ) x i out (ave) example ) where v in =1.8v, v o ut =1.2v, i out (ave) = 1a, calculation based on ambient temperature (ta) w aj ta tj ? ??? ? 1-layer substrate (copper foil density 0.2 %) 1-layer substrate (copper foil density 7%) 2-layer substrate (copper foil density 65%) substrate size: 70mm x 70mm x 1.6mm 3 (substrate with thermal via) j -a:hson8 198.4 c /w 92.4 c /w 71.4 c /w ? ? ? ? ? ? ? ? ? ? ? ? w 6.0 a0.1 v2.1 v8.1 w n consumptio power ? ? ? ? downloaded from: http:///
20 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 hson8 4. reference landing pattern (unit: mm) lead pitch e lead pitch mie landing length l2 landing pitch b2 0.65 2.50 0.40 0.35 central pad length central pad pitch d3 e3 2.90 1.90 (note) it is recommended to design suitable for the actual application. d3 mie e3 e b2 l2 (1) substrate (copper foil density: 0.2%1 -layer) j -a=198.4c/w (2) substrate (copper foil density: 7%1 -layer) j -a=92.4c/w (3) substrate (copper foil density: 65%1 -layer) j -a=71.4c /w power dissipation [pd] [w] 0 25 75 100 125 150 50 [ c ] ambient temperature [ta] 1.0 0.5 0 2.0 1.5 (1) 0.63w (2) 1.35w (3) 1.75w downloaded from: http:///
21 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 i/o equivalent circuits vcc o ut 1 o ut 2 50k 1k 1k nrcs vcc 1k 1k 1k 1k 1k vcc in 1k vcc vfb 1k 40 0k en downloaded from: http:///
22 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 operational notes 1. reverse connection of power supply connecting the power supply in reverse polarity can damage the ic. take precautions against reverse polarity when connecting the power supply, such as mounting an external diod e between the power supply and the ics power supply terminals. 2. power supply lines design the pcb layout pattern to provide low impedance supply lines. separate the ground and supply lines of the digital and analog blocks to prevent noise in the grou nd and supply lines of the digital block from affecting the analog block. furthermore, connect a capacitor to ground at all pow er supply pins. consider the effect of temperature and aging on the capacitance value when using electrolytic capa citors. 3. ground voltage ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition. 4. ground wiring pattern when using both small-signal and large-current ground tr aces, the two ground traces should be routed separately but connected to a single ground at the reference point of the application board to avoid fluctuations in the small- signal ground caused by large currents. also ensure that the gro und traces of external components do not cause variations on the ground voltage. the ground lines must be as short an d thick as possible to reduce line impedance. 5. thermal consideration should by any chance the power dissipation rating be exc eeded, the rise in temperature of the chip may result in deterioration of the properties of the chip. the absolute maxi mum rating of the pd stated in this specification is when the ic is mounted on a 70mm x 70mm x 1.6mm glass epoxy boa rd. in case of exceeding this absolute maximum rating, increase the board size and copper area to prevent exceeding the p d rating. 6. recommended operating conditions these conditions represent a range within which the expe cted characteristics of the ic can be approximately obtained . the electrical characteristics are guaranteed under the conditi ons of each parameter. 7. inrush current when power is first supplied to the ic, it is possible that the internal logic may be unstable and inrush current ma y flow instantaneously due to the internal powering sequence and de lays, especially if the ic has more than one power supply. therefore, give special consideration to power coupling cap acitance, power wiring, width of ground wiring, and routi ng of connections. 8. operation under strong electromagnetic field operating the ic in the presence of a strong electromagnetic field ma y cause the ic to malfunction. 9. testing on application boards when testing the ic on an application board, connecting a capac itor directly to a low-impedance output pin may subject the ic to stress. always discharge capacitors completely after each process or step. the ics power supply should always be turned off completely before connecting or rem oving it from the test setup during the inspection process. to prevent damage from static discharge, ground the ic during assembly and use similar precautions during transport and storage. 10. inter-pin short and mounting errors ensure that the direction and position are correct when mounti ng the ic on the pcb. incorrect mounting may result in damaging the ic. avoid nearby pins being shorted to each other especially to ground, power supply and output pin . inter-pin shorts could be due to many reasons such as m etal particles, water droplets (in very humid environment) and unintentional solder bridge deposited in between pins during as sembly to name a few. 11. unused input terminals input terminals of an ic are often connected to the gate of a mos transistor. the gate has extremely high impedance and extremely low capacitance. if left unconnected, the e lectric field from the outside can easily charge it. the sm all charge acquired in this way is enough to produce a signi ficant effect on the conduction through the transistor and cause unexpected operation of the ic. so unless otherwise spe cified, unused input terminals should be connected to the power supply or ground line. downloaded from: http:///
23 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 operational notes - continued 12. regarding input pins of the ic this monolithic ic contains p+ isolation and p substrate layers between adjacent elements in order to keep them isolated. p-n junctions are formed at the intersection of the p layers with the n layers of other elements, creating a parasitic diode or transistor. for example (refer to figure below): when gnd > pin a and gnd > pin b, the p-n junction operates as a paras itic diode. when gnd > pin b, the p-n junction operates as a parasitic transistor. parasitic diodes inevitably occur in the structure of the ic . the operation of parasitic diodes can result in mutu al interference among circuits, operational faults, or physic al damage. therefore, conditions that cause these diodes to operate, such as applying a voltage lower than the gnd v oltage to an input pin (and thus to the p substrate) should be avoided. figure 37. example of monolithic ic structure 13. area of safe operation (aso) operate the ic such that the output voltage, output current, and p ower dissipation are all within the area of safe operation (aso). 14. thermal shutdown circuit (tsd) this ic has a built-in thermal shutdown circuit that prevent s heat damage to the ic. normal operation should always be within the ics power dissipation rating. if however the rating i s exceeded for a continued period, the junction temperature (tj) will rise which will activate the tsd circuit that will turn off all output pins. when the tj falls below the tsd threshold, the circuits are automatically restored to normal oper ation. note that the tsd circuit operates in a situation that exceeds th e absolute maximum ratings and therefore, under no circumstances, should the tsd circuit be used in a set design or fo r any purpose other than protecting the ic from heat damage. 15. output protection diode please add a protection diode when a large inductance co mponent is connected to the output terminal, and reverse-polarity power is possible at startup or in output off conditio n. tsd on temperature [c] (typ) hysteresis temperature [c] (typ) bd3550hfn,bd3551hfn,bd3552hfn 175 15 n n p + p n n p + p substrate gnd n p + n n p + n p p substrate gnd gnd parasitic elements pin a pin a pin b pin b b c e parasitic elements gnd parasitic elements c be transistor (npn) resistor n region close-by parasitic elements output pin (example) downloaded from: http:///
24 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 ordering information b d 3 5 5 x h f n t r part number 3550 3551 3552 package hfn : hson8 packaging and forming specification tr: emboss tape reel opposite draw-out side: 1 pin marking diagrams ? bd3550hfn ? bd3551hfn ? bd3552hfn hson8 (top view) 551 part number marking lot number 1pin mark bd3 hson8 (top view) 552 part number marking lot number 1pin mark bd3 hson8 (top view) 550 part number marking lot number 1pin mark bd3 downloaded from: http:///
25 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 physical dimension, tape and reel information package name hson8 downloaded from: http:///
26 / 26 bd3550hfn bd 3551hfn bd3552hfn tsz02201-0j2j0a601140-1-2 02.nov.2015 rev.001 ? 20 15 rohm co., ltd. all rights reserved. www.rohm.com tsz22111 14 001 revision history date revision changes 02.nov.2015 001 new release downloaded from: http:///
datasheet d a t a s h e e t notice-pga-e rev.00 2 ? 2015 rohm co., ltd. all rights reserved. notice precaution on using rohm products 1. our products are designed and manufac tured for application in ordinary elec tronic equipments (such as av equipment, oa equipment, telecommunication equipment, home electroni c appliances, amusement equipment, etc.). if you intend to use our products in devices requiring ex tremely high reliability (such as medical equipment (note 1) , transport equipment, traffic equipment, aircraft/spacecra ft, nuclear power controllers, fuel c ontrollers, car equipment including car accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or serious damage to property (?specific applications?), please consult with the rohm sale s representative in advance. unless otherwise agreed in writing by rohm in advance, rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any ro hm?s products for specific applications. (note1) medical equipment classification of the specific applications japan usa eu china class class class b class class ? class 2. rohm designs and manufactures its products subject to strict quality control system. however, semiconductor products can fail or malfunction at a certain rate. please be sure to implement, at your own responsibilities, adequate safety measures including but not limited to fail-safe desi gn against the physical injury, damage to any property, which a failure or malfunction of our products may cause. the following are examples of safety measures: [a] installation of protection circuits or other protective devices to improve system safety [b] installation of redundant circuits to reduce the impact of single or multiple circuit failure 3. our products are designed and manufactured for use under standard conditions and not under any special or extraordinary environments or conditio ns, as exemplified below. accordin gly, rohm shall not be in any way responsible or liable for any damages, expenses or losses arising from the use of an y rohm?s products under any special or extraordinary environments or conditions. if you intend to use our products under any special or extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of product performance, reliability, etc, prior to use, must be necessary: [a] use of our products in any types of liquid, incl uding water, oils, chemicals, and organic solvents [b] use of our products outdoors or in places where the products are exposed to direct sunlight or dust [c] use of our products in places where the products ar e exposed to sea wind or corrosive gases, including cl 2 , h 2 s, nh 3 , so 2 , and no 2 [d] use of our products in places where the products are exposed to static electricity or electromagnetic waves [e] use of our products in proximity to heat-producing components, plastic cords, or other flammable items [f] sealing or coating our products with resin or other coating materials [g] use of our products without cleaning residue of flux (ev en if you use no-clean type fluxes, cleaning residue of flux is recommended); or washing our products by using water or water-soluble cleaning agents for cleaning residue after soldering [h] use of the products in places subject to dew condensation 4. the products are not subjec t to radiation-proof design. 5. please verify and confirm characteristics of the final or mounted products in using the products. 6. in particular, if a transient load (a large amount of load applied in a short per iod of time, such as pulse. is applied, confirmation of performance characteristics after on-boar d mounting is strongly recomm ended. avoid applying power exceeding normal rated power; exceeding the power rating under steady-state loading c ondition may negatively affect product performance and reliability. 7. de-rate power dissipation depending on ambient temperature. when used in sealed area, c onfirm that it is the use in the range that does not exceed t he maximum junction temperature. 8. confirm that operation temperat ure is within the specified range described in the product specification. 9. rohm shall not be in any way responsible or liable for fa ilure induced under deviant condi tion from what is defined in this document. precaution for mounting / circuit board design 1. when a highly active halogenous (chlori ne, bromine, etc.) flux is used, the resi due of flux may negatively affect product performance and reliability. 2. in principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method must be used on a through hole mount products. if the flow sol dering method is preferred on a surface-mount products, please consult with the rohm representative in advance. for details, please refer to rohm mounting specification downloaded from: http:///
datasheet d a t a s h e e t notice-pga-e rev.00 2 ? 2015 rohm co., ltd. all rights reserved. precautions regarding application examples and external circuits 1. if change is made to the constant of an external circuit, pl ease allow a sufficient margin considering variations of the characteristics of the products and external components, including transient characteri stics, as well as static characteristics. 2. you agree that application notes, re ference designs, and associated data and in formation contained in this document are presented only as guidance for products use. theref ore, in case you use such information, you are solely responsible for it and you must exercise your own indepen dent verification and judgment in the use of such information contained in this document. rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of such information. precaution for electrostatic this product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. please take proper caution in your manufacturing process and storage so that voltage exceeding t he products maximum rating will not be applied to products. please take special care under dry condit ion (e.g. grounding of human body / equipment / solder iron, isolation from charged objects, se tting of ionizer, friction prevention and temperature / humidity control). precaution for storage / transportation 1. product performance and soldered connections may deteriora te if the products are stor ed in the places where: [a] the products are exposed to sea winds or corros ive gases, including cl2, h2s, nh3, so2, and no2 [b] the temperature or humidity exceeds those recommended by rohm [c] the products are exposed to di rect sunshine or condensation [d] the products are exposed to high electrostatic 2. even under rohm recommended storage c ondition, solderability of products out of recommended storage time period may be degraded. it is strongly recommended to confirm sol derability before using products of which storage time is exceeding the recommended storage time period. 3. store / transport cartons in the co rrect direction, which is indicated on a carton with a symbol. otherwise bent leads may occur due to excessive stress applied when dropping of a carton. 4. use products within the specified time after opening a humidity barrier bag. baking is required before using products of which storage time is exceeding the recommended storage time period. precaution for product label qr code printed on rohm products label is for rohm?s internal use only. precaution for disposition when disposing products please dispose them proper ly using an authorized industry waste company. precaution for foreign exchange and foreign trade act since concerned goods might be fallen under listed items of export control prescribed by foreign exchange and foreign trade act, please consult with rohm in case of export. precaution regarding intellectual property rights 1. all information and data including but not limited to application example contained in this document is for reference only. rohm does not warrant that foregoi ng information or data will not infringe any intellectual property rights or any other rights of any third party regarding such information or data. 2. rohm shall not have any obligations where the claims, actions or demands arising from the co mbination of the products with other articles such as components, circuits, systems or external equipment (including software). 3. no license, expressly or implied, is granted hereby under any intellectual property rights or other rights of rohm or any third parties with respect to the products or the informati on contained in this document. pr ovided, however, that rohm will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to manufacture or sell products containing the produc ts, subject to the terms and conditions herein. other precaution 1. this document may not be reprinted or reproduced, in whol e or in part, without prior written consent of rohm. 2. the products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written consent of rohm. 3. in no event shall you use in any wa y whatsoever the products and the related technical information contained in the products or this document for any military purposes, incl uding but not limited to, the development of mass-destruction weapons. 4. the proper names of companies or products described in this document are trademarks or registered trademarks of rohm, its affiliated companies or third parties. downloaded from: http:///
datasheet datasheet notice ? we rev.001 ? 201 5 rohm co., ltd. all rights reserved. general precaution 1. before you use our pro ducts, you are requested to care fully read this document and fully understand its contents. rohm shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny rohms products against warning, caution or note contained in this document. 2. all information contained in this docume nt is current as of the issuing date and subj ec t to change without any prior notice. before purchasing or using rohms products, please confirm the la test information with a rohm sale s representative. 3. the information contained in this doc ument is provi ded on an as is basis and rohm does not warrant that all information contained in this document is accurate an d/or error-free. rohm shall not be in an y way responsible or liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or concerning such information. downloaded from: http:///

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