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product structure silicon monolithic integrated circuit this product has no designed protection against radioactive ra ys . 1/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 tsz22111 ? 14 ? 001 www.rohm.com 1 .5 v to v cc -1v, 1.5a 1 ch ultra low dropout linear regulator bd352 81 hfn general description bd35281hfn is an ultra low-dropout linear chipset regulator that operates from a very low input supply. it offers ideal performance in low input voltage to low ou tput 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 =150m (max). by lowering the dropout voltage, the regulator achieves high output current of up to (i outmax =1.5a) thereby, reducing conversion loss, making it comparable to a switching regulator and its power transistor, choke coil, and rectifier diode constituen ts . it is a low-cost design and is available in significant ly downsized package profiles. the 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 output voltage circuit (1.20v1 %) built-in vcc undervoltage lockout circuit (v cc =3.80v) nrcs (soft start) function reduces the magnitude of in-rush current internal n-channel mosfet driver offers low on -resistance built-in short circuit protection (scp) built-in current limit circuit (1.5a min) built-in thermal shutdown (tsd) circuit tracking function applications notebook computers, desktop computers, lcd-tv, dvd, digital appliances key specifications ? in input voltage range: 1.5v to v cc -1v ? vcc input voltage range: 4.3v to 5.5v ? output voltage: 1.2v(fixed) ? output current: 1.5 a (max) ? on -resistance: 100m (typ ) ? standby current: 0a (typ) ? operating temperature range: -10c to +100c package w(typ) x d(typ) x h(max) hson8 2.90mm x 3.00mm x 0.60mm datashee t datashee t downloaded from: http:///
2/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn typical application circuit , block diagram pin configuration pin description pin no. pin name pin function 1 v cc power supply pin 2 en enable input pin 3 nrcs in -rush current protection (nrcs) capacitor connection pin 4 in input voltage pin 5 o ut output voltage pin 6 vos output voltage control pin 7 fb reference voltage feedback pin 8 gnd ground pin - fin connected to heatsink and gnd reference block v in uvlolatch current limit en v cc v cc v cc v cc en uvlo1 uvlo2 v ref1 gnd cl uvlo1 uvlo2 tsd scp en uvlo1 cl v cc v ref2 in out fb in out v os nrcs 1 2 3 8 5 4 nrcs tsd nrcs0.3. vref1 x 0.4 fb scp/tsd latch latch en uvlo1 en/uvlo nrcs c 1 c 2 7 c nrcs c 3 c fb 6 r 2 r 1 r 2 r 1 top view gnd fb fin v os 5 6 7 8 out vcc en nrcs in 4 3 2 1 downloaded from: http:///
3/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn description of blocks 1. amp this is an error amp that compares the reference voltage (0.65 v) with fb voltage to drive the output n-channel fet. frequency optimization aids in attaining rapid transi en t response, and to support the use of ceramic capacitors on the output. amp output voltage ranges from gnd to vcc. when en is off, o r when uvlo is active, output goes low and the output of the n-channel fet switch es to off state. 2. en the en block controls the on and off state of the regulator vi a the en logic input pin. during the off state, circuit voltage stabilizes at 0a, which minimiz es current consumption during standby mode. the fet is switched on to enable the discharge of the nrcs and out, thereby draining the excess charge and preven ting the load side of an ic from malfunctioning. since there is no electrical connection required (e.g. between the vcc pin and the esd prevention diode), module operation is independent of the input sequenc e. 3. vccuvlo to prevent malfunctions that can occur during sudden decre ase in vcc, the uvlo circuit switches the output to off state, 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. in uvlo when in voltage exceeds the threshold voltage, in uvlo becomes active. once active, the status of output vol tage remains on even if in voltage drops. (when in voltage drops, scp engages and output swi tches off.) unlike en and vcc, it is active at output startup. in uvlo can be restored either by reconnecting the en pin or vcc pin. 5. current limit during on state, the current limit function monitors the output current of the ic against the current limit value. when output current exceeds this value, th is block lowers the output current to protect the load of the ic. wh en it overcomes the overcurrent state, output voltage is restored to the normal value. however, when output voltage falls belo w the scp startup voltage, the scp function becomes active and the output switc hes off. 6. nrcs (non rush current on start- up) the soft start function 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 reache s 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 calculated by the formula below. ? ? nrcs fb nrcsp nrcs i v c typ t ? ? 7. ts d (thermal shut down) the shutdown (tsd) circuit is automatically latched off when the chip temperature exceed s the threshold temperature after the programmed time period elapses, thus protect ing the ic against thermal runaway and heat damage. since the tsd circuit is designed only to shut down the ic in the occ urrence of extreme heat, it is important hat the tj (max) parameter should not be exceeded in the thermal design in order to avoid potential problems with the tsd. 8. in the in line acts as the major current supply line, and is c onnected to the output n-channel fet drain. since there is no electrical connection (such as between the vcc pin and the esd protecti on diode ) required , in operates independent of the input sequence. however, since an output n-channel fet bo dy di ode exists between in and out, a in-o ut electric (diode) connection is present. therefore, when output is sw itched on or off, reverse current may flow from in to out. 9. scp when output voltage (out) drops, the ic assumes that v o pin is shorted to gnd and switches the output voltage off . after the gnd short has been detected and the programmed dela y time has elapsed, the output is latched off. scp is also effective during output startup. scp condition can be cle ared either by reconnecting the en pin or vcc pin. delay time is calculated by the formula below. downloaded from: http:///
4/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn absolute maximum ratings (ta=25 c ) parameter symbol rating unit input voltage 1 v cc +6.0 (note 1) v input voltage 2 v in +6.0 (note 1) v maximum output current i o ut 2 (note 1) a enable input voltage v en -0.3 to +6.0 v power dissipation 1 pd1 0.63 (note 2) w power dissipation 2 pd2 1.35 (note 3) w power dissipation 3 pd3 1.75 (note 4) w operating temperature range topr -10 to +100 c storage temperature range tstg -55 to +125 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, copper foil area : less than 0.2 %) (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, copper foil area : less than 7.0%) (note 4) derate by 14.0mw/ c for ta above 25 c (when mounted on a 70mm x 70mm x 1.6mm glass-epoxy board , 1-layer, copper foil area : less than 65.0%) caution: operating the ic over the absolute maximum ratings may damage the ic. th e 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 ope rated over the absolute maximum ratings. recommended operating ratings (ta=25 c ) parameter symbol rating unit min max input voltage 1 v cc 4.3 5.5 v input voltage 2 v in 1.5 v cc -1 (note 5) v output voltage setting range v o ut 1. 2 (fixed) v enable input voltage v en -0.3 +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. downloaded from: http:///
5/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn electrical characteristics (unless otherwise specified, ta=25 c , v cc =5v, v en =3v, v in =1.7v) parameter symbol limit unit conditions min typ max bias current i cc - 0.7 1.2 ma vcc shutdown mode current i st - 0 10 a v en =0v output current i o ut 1.5 - - a feedback voltage 1 v vos1 1.188 1.200 1.212 v feedback voltage 2 v vos2 1.176 1.200 1.224 v tj=- 10 c to +100 c 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 =1.5v to 3.3v load regulation reg.l - 0.5 10 mv i out =0 a to 1.5a output on-resistance r on - 100 150 m i out =1.5a,v in =1.2v, tj=- 10 c to +100 c standby discharge current i den 1 - - ma v en =0v, v out =1v [enable] enable pin input voltage high v enhigh 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 [n rcs] nrcs charge current i nrcs 12 20 28 a nrcs standby voltage v stb - 0 50 mv v en =0v [uvlo] vcc undervoltage lockout threshold voltage v ccuvlo 3.5 3.8 4.1 v vcc:sweep- up vcc undervoltage lockout hysteresis voltage v cchys 100 160 220 mv vcc:sweep- dow n in undervoltage lockout threshold voltage v inuvlo 0.72 0.84 0.96 v in:sweep- up [scp] scp start up voltage v o ut scp v o ut x 0.3 v out x 0.4 v out x 0.5 v scp threshold voltage t scp 45 90 200 sec downloaded from: http:///
6/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn typical waveforms figure 1. transient response (0a to 1.5 a) c out =100f c fb =1000pf 1a/div i out v out 50mv/div t (10 sec/div) 66mv 1.5a figure 2. transient response (0a to 1.5 a) c out =47f c fb =1000pf t (10 sec/div) 91mv 1.5a 2a/div i out v out 50mv/div figure 3. transient response (0a to 1.5 a) c out =22f c fb =1000pf t (10 sec/div) 1.5a 108mv 1a/div i out v out 50mv/div figure 4. transient response (1.5a to 0a) c out =100f c fb =1000pf 1.5a 51mv t (1 00sec/div) 1a/div i out v out 50mv/div downloaded from: http:///
7/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn figure 5. transient response (1.5a to 0a) c out =47f c fb =1000pf t (1 00sec/div) 80mv 1.5a 1a/div i out v out 50mv/div typical waveforms C continued figure 6. transient response (1.5a to 0a) c out =22f c fb =1000pf t (1 00sec/div) 98mv 1.5a 1a/div i out v out 50mv/div figure 7. waveform at output start t (200 se c/div) v en v nrcs v out figure 8. wa veform at output off t (200 sec/div) v en v nrcs v out downloaded from: http:///
8/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn figure 9. input sequence v cc v en v in v out v cc to v in to v en typical waveforms C continued figure 10. in put sequence v in to v cc to v en v cc v en v in v out figure 11. input sequence v en to v cc to v in v cc v en v in v out figure 12. in put sequence v cc v en v in v out v cc to v en to v in downloaded from: http:///
9/ 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn typical waveforms C continued figure 14. in put sequence v en to v in to v cc v cc v en v in v out figure 13. input sequence v in to v en to v cc v cc v en v in v out downloaded from: http:///
10 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn typical performance curves figure 17. i in vs junction temperature 1.0 1.2 1.4 1.6 1.8 2.0 -50 -25 0 25 50 75 100 125 150 tj [ ] iin [ma] - 50 - 25 0 25 50 75 100 125 150 junction temperature : tj [c] i in [ma] figure 18. i st vs junction temperature 0.0 0.5 1.0 1.5 2.0 2.5 3.0 -50 -25 0 25 50 75 100 125 150 tj [ ] istb [a] - 50 - 25 0 25 50 75 100 125 150 junction temperature : tj [c] i st [a] figure 15. output voltage vs junction temperature (i out =0ma) 1.15 1.17 1.19 1.21 1.23 1.25 -50 -25 0 25 50 75 100 125 150 tj [ ] vo [v] - 50 - 25 0 25 50 75 100 125 150 output voltage : v out [v] junction temperature : tj [c] figure 16. ci rcuit current vs junction temperature 0.4 0.5 0.6 0.7 0.8 0.9 -50 -25 0 25 50 75 100 125 150 tj [ ] icc [ma] - 50 - 25 0 25 50 75 100 125 150 circuit current : i cc [ma] junction temperature : tj [c] downloaded from: http:///
11 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn typical performance curves C continued figure 20. enable in put bias current vs junction temperature 0 1 2 3 4 5 6 7 8 9 10 -50 -25 0 25 50 75 100 125 150 tj [ ] ien [a] - 50 - 25 0 25 50 75 100 125 150 junction temperature : tj [c] enable input bias current : i e n [a] figure 19. nrcs charge current vs junction temperature 10 11 12 13 14 15 16 17 18 19 20 -50 -25 0 25 50 75 100 125 150 tj [ ] inrcs [a] - 50 - 25 0 25 50 75 100 125 150 junction temperature : tj [c] nrcs charge current : i nrcs [a] figure 21. output on-resistance vs junction temperature (v cc =5v/v out =1.2v) 50 70 90 110 130 150 -50 -25 0 25 50 75 100 125 150 tj [ ] ron [m] - 50 - 25 0 25 50 75 100 125 150 junction temperature : tj [c] output on-resistance : r on [m] 75 85 95 105 115 125 135 3 4 5 6 7 8 vcc [v] ron [mo] figure 22. ou tput on-resistance vs input voltage 1 (v out =1.2v) input voltage 1 : v cc [v] output on-resistance : r on [m] downloaded from: http:///
12 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn timing chart en on/off v cc on/off in v cc en nrcs out t startup 0.65v(typ) in v cc en nrcs out t hysteresis uvlo startup 0.65v(typ) downloaded from: http:///
13 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn timing chart C continued in on scp off v cc en nrcs out v in uvlo in v cc en nrcs out in scp startup voltage scp delay time downloaded from: http:///
14 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn application information 1. evaluation board bd352 81 hfn evaluation board list component rating manufacturer product name u1 - rohm bd35 281 hfn c 1 1f murata grm188b11a105kd c 3 10 f kyocera cm32x5r 10 6m10a c 5 22 f kyocera cm32x5r226m10a c 11 0.01f murata grm188b11h103kd c 13 1000pf murata grm188b11h102kd r 4 0 - jumper r 8 0 - jumper bd352 81 hfn evaluation board layout (2nd layer and 3rd layer are gnd line. ) bd352 81 hfn evaluation board schematic 1 2 3 4 8 7 6 5 v cc v cc v cc gnd gnd tp1 out fb gnd vos nrcs v in r 4 r 8 c = c 6 c 8 c 9 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 7 5 6 8 4 3 2 1 gnd_s out _s gnd gnd gnd c 13 gnd tp2 v cc jpf2 jpf1 r 9 c 14 2 3 4 5 v in _s u3 gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd gnd g nd u1 bd352 81h fn silk screen top layer bottom layer downloaded from: http:///
15 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn 2. recommended circuit example component recommended value programming notes and precautions c 3 22f to assure output voltage stability, ensure that the outp ut capacitors are connected between out pin and gnd. output capacitors play a role in loop gain phase compensation and in mitigating output fluctuation during rapid changes in load level. in sufficient capacitance may cause oscillation, while hig h equivalent series resistance (esr) will exacerbate output voltage fluctuation u nder rapid load change conditions. while a 22f ceramic capacitor is recomended, actual stability is highly dependent on temperature and load conditions. also, note tha t connecting different types of capacitors in series may result in insufficient tot al phase compensation, thus causing oscillation. please confirm operation across a va riety of temperature and load conditions. c 1 /c 2 1f/10f input capacitors reduce the output impedance of the voltage supply source connected to the input pins (vcc, in). if the impedance of th is power supply were to increase, input voltage (v cc , v in ) could become unstable, leading to oscillation or lowered ripple rejection function. while a low- esr 1f/ 10 f capacitor with minimal susceptibility to temperature is recommended, stability is highly dependent on the input power supply characteristics and the substrate wiring pattern. in light of thi s information, please confirm operation across a variety of te mperature and load conditions. c 4 0.01f the non rush current on startup (nrcs) function is built into the ic to preve nt rush current from going through the load (in to o ut ) and affects output capacitors at power supply start-up. constant current comes from the nrcs pin when en is high or when the uvlo function is deactivated. the temporary reference voltage is proportional to time, due to the current charge of the nrcs pin capacitor, and outpu t voltage start-up is proportional to this reference voltage . capacitors with low susceptibility to temperature are recommended, to ensure a st able soft-start time. c 5 1000pf this component is employed when the c 3 capacitor causes, or may cause, oscillation. it provides more precise internal phase correction. 4 3 2 1 8 7 6 5 c 1 v cc r 4 v en c 4 v in c 2 c 3 gnd fb out c 5 v cc en in vos out gnd fb nrcs downloaded from: http:///
16 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn 3. power dissipation 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 100 c . (2) chip junction temperature (tj) can be no higher than 150 c . chip junction temperature can be determined as follows: calculation based on ambient temperature (ta) w aj ta tj ? ??? ? j -a:hson8 198.4 c /w 92.4 c /w 71.4 c /w 1-layer substrate (copper foil area : below 0.2%) 1-layer substrate (copper foil area : 7%) 2-layer substrate (copper foil area : 65%) substrate size: 70 mm x 70 mm x 1.6mm 3 (substrate with thermal via) 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). t his package is so small (size: 2.9 mm x 3.0mm) that it is not available to layout the via in the bottom of ic. spreading t he pattern and increasing the number of via as shown in the figure below, enable to achieve superior heat radiation ch aracteristic. (this figure is an image only. it is recommended that the via size and the number are designed suitable for the ac tual situation.). most of the heat loss in bd352 81 hfn occurs at the output n-channel fet. power loss is determine d by the total v in -v out voltage and output current. be sure to confirm the system in put and output voltage and the output current conditions in relation to the heat dissipation characteristics of the in and out in the design. bearing in mind that heat dissipatio n may vary substantially depending on the substrate employed (d ue to the power package incorporated in the bd352 81 hfn ) make sure to factor in conditions such as substrate size into the thermal design. ? ? (ave) i ) (v voltage output -) (v voltage input = (w) n consumptio power out out out ? example) where v in =1.7v, v o ut =1.2v, i out (ave) = 2 a, ? ? 0.75(w) = 1.5(a) (v) 1.2 - (v) 1.7 = (w) n consumptio power ? downloaded from: http:///
17 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn hson8 i /o equivalent circuits 400k en 1k in v cc out 50k 10k 1 k v cc fb 1k 1k v os nrcs v cc 1k 1k 1k 90k 210k 1k v cc 1k 1k 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 (1) 1 layer substrate (substrate surface copper foil area: below 0.2 %) j -a=198.4c/w (2) 1 layer substrate (substrate surface copper foil area:7%) j -a=92.4c/w (3) 1 layer substrate (substrate surface copper foil area:65%) j -a=71.4c/w downloaded from: http:///
18 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn operational notes 1. reverse connection of power supply connecting the power supply in reverse polarity can damage th e ic. take precautions against reverse polarity when connecting the power supply, such as mounting an external diode between the power supply and the ic s power supply pin s. 2. power supply lines design the pcb layout pattern to provide low impedance supp ly lines. separate the ground and supply lines of the digital and analog blocks to prevent noise in the gro und and supply lines of the digital block from affecting the analog block. furthermore, connect a capacitor to ground at all power 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 tra ces, 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 grou nd traces of external components do not cause variations on the ground voltage. the ground lines must be as short and thick as possible to reduce line impedance. 5. thermal consideration should by any chance the power dissipation rating be ex ceeded the rise in temperature of the chip may result in deterioration of the properties of the chip. in case of exceedi ng this absolute maximum rating, increase the board size and copper area to prevent exceeding the pd 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 condi tions of each parameter. 7. inrush current when power is first supplied to the ic, it is possible th at the internal logic may be unstable and inrush current may flow instantaneously due to the internal powering sequence and del ays, 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 routing 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 capa citor directly to a low-impedance output pin may subject the ic to stress. always discharge capacitors completely after e ach process or step. the ics power supply should always be turned off completely before connecting or remo ving it from the test setup during the inspection process. to prevent damage from static discharge, ground the ic during ass embly and use similar precautions during transport and storage. 10. inter-pin short and mounting errors ensure that the direction and position are correct when mountin g the ic on the pcb. incorrect mounting may result in damaging the ic. avoid nearby pins being shorted to each o ther 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 pins input pins 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 electric field from the outside can easily charge it. the small c harge acquired in this way is enough to produce a significan t effect on the conduction through the transistor and caus e unexpected operation of the ic. so unless otherwise specifie d, unused input pins should be connected to the power supply or ground line. downloaded from: http:///
19 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn operational notes C continued 12. regarding the input pin 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 mutual interference among circuits, operational faults, or physica l damage. therefore, conditions that cause these diodes to operate, such as applying a voltage lower than the gnd vo ltage to an input pin (and thus to the p substrate) should b e avoided. figure 23. example of monolithic ic structure 13. area of safe operation (aso) operate the ic such that the output voltage, output current, and power 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 prevents heat damage to the ic. normal operation should always be within the ics power dissipation rating. if however the rating is exceeded for a continued period, the junction temperature (tj) will rise which will activate the tsd circuit that will turn off all output pins. the ic should be powered down and turned on again to resume normal operation becau se the tsd circuit keeps the outputs at the off state even if the tj falls below the tsd threshold. note that the tsd circuit operates in a situation that exceed s the absolute maximum ratings and therefore, under no circumstances, should the tsd circuit be used in a set design or for a ny purpose other than protecting the ic from heat damage. 15. output pin design pcb layout pattern to provide low impedance gnd and su pply lines. to obtain a low noise ground and supply line, separate the ground section and supply lines of th e digital and analog blocks. furthermore, for all power sup ply terminals to ics, connect a capacitor between the power suppl y and the gnd terminal. when applying electrolytic capacitors in the circuit, not that capacitance characteristic va lues are reduced at low temperatures. tsd on temperature [ c ] (typ) bd352 81 hfn 175 output pin (example) 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 downloaded from: http:///
20 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn ordering information b d 3 5 2 8 1 h f n t r part number package hfn : hson8 packaging and forming specification tr : embossed tape and reel marking diagram hson8 (top view) 281 part number marking lot number 1pin mark d 3 5 downloaded from: http:///
21 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn physical dimension, tape and reel information package name hson8 downloaded from: http:///
22 / 22 tsz02201-0j2j0a601060-1-2 ? 20 15 rohm co., ltd. all rights reserved. 02.nov.2015 rev.001 www.rohm.com tsz22111 ? 15 ? 001 bd35281hfn 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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