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product structure silicon monolithic integrated circuit this product has no designed protection against radioactive ra ys . 1/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17.feb.2015 rev.002 tsz22111 ? 14 ? 001 www.rohm.com 3.5v to 14v, 0 .8 a 1ch synchronous buck converter integrated mosfet bd8312h fn general description bd8312hfn can produce 1.2v, 1.8v, 3.3v, or 5v step ped -down output voltages from a power supply composed of 4 batteries, which can be li2cell, li3cell, or from a 5v/12v fixed power supply line. the built-in synchronous rectification switches are capable of withstanding up to15v. this ic has a flexible phase compensation system and a switching frequency of 1.5mhz allowing the use of smaller external output ind uctor and capacitor making the construction of a compact power supply really easy. features ? built-in 1.0a/15v pch/nch synchronous rectification sw ? on -chip phase compensation device between input and output of error amp. ? built-in soft-start function. ? bui lt -in timer latch system for short circuit protection function. application for portable equipments like dsc/dvc powered by 4 dry batteries or li2cell and li3cell, or general consumer-equipment with 5v/12 v lines key specifications ? i nput voltage range: +3.5v to + 14v ? output voltage range: +1.2v to + 12v ? output current: 0 .8 a(max) ? switching frequency: 1.5mhz(typ) ? pch fet on-resistance: 450m(typ) ? nch fet on-resistance: 300m(typ) ? standby current: 0 a( typ ) ? operating temperature range: - 25 c to +85c package w (typ) x d (typ) x h (ma x) typical application circuit input: 4.5v to 10v, output: 3.3v / 500ma figure 1 . typical application circuit hson8 2.90mm x 3.00mm x 0.60mm v bat =4.5v to 10v lx datashee t downloaded from: http:///
2/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn pin configuration pin description block diagram pin no. pin name function 1 gnd ground pin 2 vcc supply voltage input pin for control circuit 3 vreg 5v output terminal of regulator for internal circuit 4 pgnd power switch ground pin 5 lx power switch terminal for external coil 6 pvcc supply voltage input pin for power switches 7 stb on/off pin 8 inv error amp input pin figure 3. block diagram vcc inv vreg pgnd gnd stb pvcc figure 2. pin configuration (top view) lx downloaded from: http:///
3/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn description of blocks (1) reference this block produces the 1.0v internal reference voltage of the error a mp. (2) 5v r eg this block produces a 5v regulated voltage supply for the internal analog circuit. bd8312hfn is equipped with this regulator for the purpose of protecting the internal circuit from high voltages. the output of this block decreases wh en v cc is less than 5v, increasing the pmos on- resistance and decreasing the dc/dc converters power efficienc y and maximum output current (please see data in figure 15, 16, 17 and 1 8). (3) uvlo this circuit prevents malfunction of the internal circuit during activation of the power supply voltage or during low power supply voltage. it monitors the vcc pin voltage, turns off all output fet and dc/dc converter output, and resets the timer latch of the internal scp circuit and soft- start circuit when v cc voltage becomes lower than 2.9v. typical uvlo hysteresis is 200 mv. (4) scp scp is a timer latch system for short circuit protection. when the dc/dc converter is at 100% duty, the internal scp circuit starts counting. the internal counter is in-syn c with osc so that the latch circuit is activated to turn off the dc/dc converters output after about 2.7 msec or after the coun ter counts about 4000 clock pulses. to reset the latch circuit, turn off the stb pin once, then, turn it on again. or, turn the powe r supply off and then on again. (5) osc circuit that generates oscillating saw-tooth waveform signal with a fixed frequency of 1.5 mhz. (6) error amp the error amplifier detects the output signal and output pwm control signals. the internal reference voltage is set at 1.0v. a primary phase compensation device of 200 pf, 62k is built -in between the inverting input terminal and the output terminal of this error amp. (7) pwm comp pwm comp is the voltage- to -pulse-width converter for controlling the output voltage corre sponding to the input voltage. it compares the internal slope waveform with the error am p output voltage, then controls the pulse width of the output to the driver. (8) soft start this circuit prevents inrush current during startup by gradu ally increasing the output voltage of the dc/dc converter.. soft-start time is in-sync with the internal osc so that the output voltage of the dc/dc converter reaches the set voltage after about 8000 oscillations. (9) pre driver/timing control cmos inverter circuit for driving the built-in synchronous rectification pch/nch fet switch. the synchronous rectification off time for preventing feed through is about 25 nsec. (10) stby_io voltage applied on stb pin (7 pin) controls the on/off state of the ic. the ic is turned on when a voltage of 2.5v or higher is applied and turned off when the terminal is open or 0v is applied. a pull-down resistor which is approximately 400 k is built -in. (11) pch/nch fet sw built-in synchronous rectification fet for switching the coil current of the dc/dc converter. the switch is a combination of a pch fet rated at 15v with r on of 450m and a nch fet also rated at 15v with ron of 300m. since the current rating of this fet is 1.0a, the output current including the ripple current of the coil should not exceed this limit. downloaded from: http:///
4/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn absolute maximum ratings parameter symbol rating unit maximum applied power voltage v cc , pv cc 15 v maximum input current i inmax 1.0 a power dissipation pd 0. 63 (note 1) w operating temperature range topr -25 to +85 c storage temperature range tstg -55 to +150 c junction temperature tjmax +150 c (note 1) when used at ta = 25c or more and installed on a 70x 70 x1.6 t mm board, the rating is reduced by 5.04mw/c. caution: operating the ic over the absolute maximum ratings may dam age the ic. the damage can either be a short circuit between pi ns or an open circuit between pins and the internal circuitry. therefore, it is important to consi der circuit protection measures, such as adding a fuse, in case the ic is operated over the absolute maximum ratings. recommended operating conditions (ta = 25c) parameter symbol rating unit power s upply voltage v cc 3.5 to 14 v output voltage v out 1.2 to 12 v electrical characteristics (unless otherwise specified, ta = 25c , v cc = 7.4 v) parameter symbol limit unit conditions min typ max [low voltage input malfunction preventing circuit] detection threshold voltage v uv - 2.9 3.2 v vreg monitor hysteresis range v uvhy 100 200 300 mv [oscillator] oscillation frequency f osc 1.38 1.5 1.62 mhz [regulator] output voltage v reg 4.65 5.0 5.35 v [error amp] inv threshold voltage v inv 0.99 1.00 1.01 v input bias current i inv - 50 0 + 50 na v cc =12.0v , v inv =6.0v soft-start time t ss 3.2 5.3 7.4 msec [pwm comparator] lx max duty d max - - 100 (note 1) % [output] pmos on-resistance r onp - 450 600 m nmos on-resistance r onn - 300 420 m leak current i leak -1 0 +1 a [stb] stb pin control voltage operation v stbh 2.5 - 11 v no -operation v stbl -0.3 - +0.3 v stb p in p ull -down resistance r stb 250 400 700 k [circuit current] standby current v cc p in i stb1 - - 1 a pv cc p in i stb2 - - 1 a circuit current at operation v cc i cc1 - 600 900 a v inv =1.2v circuit current at operation pvcc i cc2 - 30 50 a v inv =1.2v (note 1) 100% is max duty as behavior of a pwm comparator. where in high side pmos is 100% at on state because the same or less in put voltage than output voltage is supplied. this causes the scp to activate and stop the op eration of the dc/dc converter . downloaded from: http:///
5/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn typical performance curves (unless otherwise specified, ta = 25c , v cc = 7.4v figure 4. inv threshold vs temperature inv threshold [v] temperature [c] 0.98 0.99 1.00 1.01 1.02 -40 -20 0 20 40 60 80 100 120 figure 5. inv threshold vs power s upply voltage inv threshold [ v ] v cc [v] 0.98 0.99 1.00 1.01 1.02 0 5 10 figure 6. vreg output vs temperature temperature [ c] v reg voltage [ v] 4.7 4.8 4.9 5.0 5.1 5.2 5.3 -40 0 40 80 120 figure 7. vreg output vs power s upply voltage v reg [v] v cc [v] 0 1 2 3 4 5 6 7 8 0 2 4 6 8 10 12 14 downloaded from: http:///
6/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn typical performance curves C continued (unless otherwise specified, ta = 25c , v cc = 7.4v) figure 8. frequency vs temperature frequency [mhz] temperature [c] 1.3 1.4 1.5 1.6 1.7 -40 0 40 80 120 figure 9. frequency vs power supply voltage frequency [mhz] v cc [v] 1.3 1.4 1.5 1.6 1.7 3 6 9 12 15 figure 10. uvlo threshold vs environmental temperature (uvlo threshold) uvlo threshold [ v ] environmental temperature ta [c] hysteresis voltage vhys [ v ] 2.50 2.70 2.90 3.10 3.30 3.50 -40 0 40 80 120 0.00 0.05 0.10 0.15 0.20 0.25 uvlo release voltage hysteresis width uvlo detection voltage 100 200 300 400 500 -40 0 40 80 120 i d =500ma figure11. nch fet on -resistance vs temperature nch on -resistance [ m? ] temperature [c] downloaded from: http:///
7/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn typical performance curves C continued (unless otherwise specified, ta = 25c, v cc = 7.4v 0 100 200 300 400 500 600 3 6 9 12 15 i d =500ma figure 12. nch fet on-resistance vs v cc nch on -resistance [ m ] v cc [v] i d =500ma figure 13. pch fet on-resistance vs temperature temperature [o c] pch on -resistance [m ] 0 200 400 600 800 -40 0 40 80 120 0 200 400 600 800 1000 3 6 9 12 15 i d =500ma figure 14. pch fet on-resistance vs v cc pch on -resistance [m ] v cc [v] figure 15. pch fet on-resistance vs i o (v cc =3.5v) pmos on-resistance [ ] i o [a] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 1.0 2.0 ta=25 oc ta=85 oc ta=- 25 oc downloaded from: http:///
8/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn typical performance curves C continued (unless otherwise specified, ta = 25c , v cc = 7.4v figure 16. pch fet on resistance vs i o (v cc =4.0v) pmos on -resistance [ ] i o [a] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 1.0 2.0 ta=25 oc ta=85 oc ta=- 25 oc 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 1.0 2.0 figure 17. pch fet on-resistance vs i o (v cc =4.5v) pmos on -resistance [ ] i o [a] ta=- 25 oc ta=25 oc ta=85 oc figure 18. pch fet on-resistance vs i o (v cc =5.0v) pmos on -resistance [ ] i o [a] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 1.0 2.0 figure 19. stb threshold vs temperature stb voltage [v] ta [c] 1.0 1.5 2.0 2.5 -50 0 50 100 150 on off downloaded from: http:///
9/ 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn typical performance curves- continued (unless otherwise specified, ta = 25c, v cc = 7.4 v) figure 20. circuit current i cc vs temperature temperature [o c] i cc [a] 0 200 400 600 800 1000 -40 0 40 80 120 figure 21. circuit current i cc vs v cc v cc [v] i cc [a] 0 200 400 600 800 1000 0 2 4 6 8 10 12 14 downloaded from: http:///
10 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn application information 1. example of application input: 4.5v to 10v, output: 3.3v / 500 ma vreg pgnd vcc gnd pvcc inv lx stb vt=v 1 f grm188b11a105ka61 mraa 4.7 h mtoko 1 f grm188b11a105ka61 mraa 10 f grm31cb11a106ka01 mraa 51k 22k 200k 10k 10pf 3.3v/500ma on/off 2. reference application data 1 figure 22. reference application diagram lx v bat =4.5v to 10v 1f 1f 10f 47 h figure 24 . load regulation (v out = 3.3v) figure 23 . power conversion efficiency (v out = 3.3v) 0 20 40 60 80 100 1 10 100 1000 output current [ma] output voltage [v] v cc =4.5v v cc =7.5v v cc =5.5v 3.25 3.27 3.29 3.31 3.33 3.35 1 10 100 1000 output voltage [v] output current [ma] v cc =4.5v v cc =5.5v v cc =7.5v downloaded from: http:///
11 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn 3. reference application data 2 (input 4.5v, 6.0v, 8.4v, 10v, output 3.3v ) figure 25 . frequency response 1 (v cc =4.5v, i o =250ma) frequency [hz] - 60 - 40 - 20 0 20 40 60 100 1000 10000 100000 1000000 gain [db] - 180 - 120 - 60 0 60 120 180 phase [deg] phase gain figure 26 . frequency response 2 (v cc =6.0v, i o =250ma) frequency [hz] - 60 - 40 - 20 0 20 40 60 100 1000 10000 100000 1000000 gain [db] - 180 - 120 - 60 0 60 120 180 phase [deg] gain phase figure 27 . frequency response 3 (v cc =8.4v, i o =250ma) frequency [hz] gain [db] phase [deg] figure 28 . frequency response 4 (v cc =10v, i o =250ma) frequency [hz] gain [db] phase [deg] downloaded from: http:///
12 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn reference application data 2 - continued (input 4.5v, 6.0v, 8.4v, 10v, output 3.3v ) figure 29 . frequency response 5 (v cc =4.5v, i o =500ma) frequency [hz] gain [db] phase [deg] figure 30 . frequency response 6 (v cc =6.0v, i o =500ma) frequency [hz] gain [db] phase [deg] figure 31 . frequency response 7 (v cc =8.4v, i o =500ma) frequency [hz] gain [db] phase [deg] figure 32 . frequency response 8 (v cc =10v, i o =500ma) frequency [hz] gain [db] phase [deg] downloaded from: http:///
13 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn 4. reference board pattern (1) the heat sink on the rear should be a gnd trace of low imped ance and at the same potential with the pgnd trace. (2) it is recommended to install a gnd pin not direc tly connected to the pgnd, as shown in the picture a bove. (3) make the patterns for vbat, lx and pgnd as wide as possible since these paths carry large current. 5. selection of parts for application (1) inductor a shielded inductor with low dcr (direct resistance component) that satisfies the current rating (current value , i peak as shown in the equation below) is recommended. inductor values affect inductor ripple current, which causes ou tput ripple. ripple current can be reduced as the coil l value becomes larger and the switching frequency becomes higher. where is the efficiency. ? i l is the output ripple current. f is the switching frequency. as a guide, inductor ripple current should be set at about 20% to 5 0% of the maximum input current. note: current flowing in the coil that is larger than the coils ra ting will bring the coil into magnetic saturation, which may lead to lower efficiency or output oscillation. select an i nductor with an adequate margin so that the peak current does not exceed the rated current of the coil. (2) output capacitor a ceramic capacitor with low esr is recommended for the output in order to reduce output ripple. there must be an adequate margin between the maximum rating and output voltage of the capacitor, taking the dc bias property into consideration. output ripple voltage is acquired by the following equation. setting must be performed so that output ripple is within the allo wable ripple voltage. figure 33 . inductor current i l i l ? ? ? (3) ][ 2 1 v r i c f i v esr l o l pp ? ?? ? ? ? ?? ? ][ 1 a f v v l v v in out out in i l ? ? ? ? ? ? ? ? (2) ? ? ? (1) ][ 2/ a i i ipeak l out ?? ? downloaded from: http:///
14 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn (3) output voltage setting the internal reference voltage of the error amp is 1.0v. output voltag e is acquired by equation (4). (4) dc/dc converter frequency response adjustment system condition for stable application. the condition for feedback system stability under negative fe edback is that the phase delay is 135 or less when gain is 1 (0db). since dc/dc converter application is sampled according to the switchi ng frequency, the bandwidth g bw of the whole system (frequency at which gain is 0 db) must be controlled to be e qual to or lower than 1/10 of the switching frequency. in summary, the conditions necessary for the dc/dc converter are: - phase delay must be 135 or lower when gain is 1 (0 db). - bandwidth g bw (frequency when gain is 0 db) must be equal to or lower than 1/1 0 of the switching frequency. to satisfy those two conditions , r 1 , r 2 , r 3 , c s and r s in figure 35 should be set as follows. (a) r 1 , r 2 , r 3 bd8312hfn incorporates phase compensation devices of r 4 =62k and c 2 =200pf. c 2 and r 1 , r 2 , and r 3 values decide the primary pole that determines the bandwidth of dc/dc converter. primary pole point frequency dc/dc converter dc gain using equations (5) and (6), the frequency f sw of point 0 db under limitation of the bandwidth of the dc gain at the primary pole point is as shown below. it is recommended that f sw should be approximately 10 khz. when load response is difficult, it may be set at approximately 20 khz. in equation (7), r 1 and r 2 , which determines the voltage value, will be in the order o f several hundred k. if an appropriate resistance value this high is not available an d routing may cause noise, the use of r 3 enables easy setting. figure 34 . setting of voltage feedback resistance fb v out c 2 r 1 r 2 rs r 4 cs r 3 inside of ic ???? (5 ) ???? (6) ???? (7) figure 35 . example of phase compensation setting where: a is the error amp gain about 100db = 10 5 b is the oscillator amplification = 0.5 v in is the input voltage v out is the output voltage ? ? ? ? ? ? o in sw v v b r r r r r c gain dc fp f ? ? ? ? ? ? ? ? ? 1 2 1 3 2 1 2 1 2 ? o in v v b a gain dc ? ? ? 1 ? ? 2 3 2 1 2 1 2 1 c r r r r r a fp ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? (4) ][ 0.1 ) ( 2 2 1 v r r r v o ? ? ? vref 1.0v vout error amp r1 r2 inv v out v ref 1.0v r 1 r 2 downloaded from: http:///
15 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn (b) cs and rs setting for dc/dc converter, the 2nd dimension pole point is caused by the coil and capacitor as expressed by the following equation. cout: output capacitor this secondary pole causes a phase rotation of 180. to secure t he stability of the system, put a zero point in 2 places to perform compensation. zero point by built-in cr zero point by c s setting f z2 frequenc y to be half to two times as large as f lc provides an appropriate phase margin. it is desirable to set rs at about 1/20 of (r 1 +r 3 ) to cancel any phase boosting at high frequencies. th ese pole points are summarized in the figure below. the actual frequency property is different from the ideal calculation because of part constants. if possible, check th e phase margin with a frequency analyzer or network analyzer. otherwise, check for the presence or absence of ringi ng by load response waveform and also check for the presence or absence of oscillation under a load of an adequa te margin. ???? (8) (9) ( 10 ) (8) (7) figure 36. example of dc/dc converter frequency property measured with fra5097 by nf corporation ???? ( 10 ) ? ? s z c r r f 3 1 2 2 1 ? ? ? ???? (9) khz cr f z 13 2 1 24 1 ? ? ? ? ? lcout f lc ? 2 1 ? downloaded from: http:///
16 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn i/o equivalent circuit figure 37. i/o equivalent circuit stb inv vreg vcc inv lx, pgnd, pv cc vreg vcc stb vcc v cc vreg vcc vreg vcc vcc vcc vreg lx pgnd pvcc pv cc lx pgnd downloaded from: http:///
17 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn 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 externa l 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 sup ply lines. separate the ground and supply lines of the digital and analog blocks to prevent noise in the ground a nd supply lines of the digital block from affecting the ana log 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 pi n at any time, even during transient condition. 4. ground wiring pattern when using both small-signal and large-current ground trace s, 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 ground 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 exc eeded the rise in temperature of the chip may result in deterioration of the properties of the chip. in case of ex ceeding this absolute maximum rating, increase the boar d 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 curren t may flow instantaneously due to the internal powering sequen ce and delays, especially if the ic has more than one power supply. therefore, give special consideration to power co upling capacitance, power wiring, width of ground wiring, and routing of connections. 8. operation under strong e le ctromagnetic 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 capacitor directly to a low-impedance output pin may subject the ic to stress. always discharge capacitors comple tely after each process or step. the ics power supply should always be turned off completely before connecting or removing it from the test setup during the inspection process. to prevent damage from static discharge, ground th e 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 mounting t he ic on the pcb. incorrect mounting may result in damaging the ic. avoid nearby pins being shorted to each oth er 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 du ring assembly to name a few. downloaded from: http:///
18 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn operational notes C continued 11. unused input pins input pins of an ic are often connected to the gate of a mos tra nsistor. the gate has extremely high impedance and extremely low capacitance. if left unconnected, the elec tric field from the outside can easily charge it. the sm all charge acquired in this way is enough to produce a sig nificant effect on the conduction through the transistor and cause unexpected operation of the ic. so unless otherwise spe cified, unused input pins should be connected to the power supply or ground line. 12. regarding the input pin of the ic this monolithic ic contains p+ isolation and p substrate l ayers 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 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 38. example of monolithic ic structure 13. thermal shutdown circuit(tsd) this ic has a built-in thermal shutdown circuit that preve nts heat damage to the ic. normal operation should always be within the ics power dissipation rating. if however the ra ting is exceeded for a continued period, the junction temperature (tj) will rise which will activate the tsd circui t that will turn off all output pins. when the tj falls be low the tsd threshold, the circuits are automatically restored to normal o peration. note that the tsd circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no circumstances, should the tsd circuit be used in a set desi gn or for any purpose other than protecting the ic from heat damage. 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:///
19 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn ordering information b d 8 3 1 2 h f n - t r part number package hfn: h so n8 packaging and forming specification tr: embossed tape and reel marking diagram hson8 (top view) 3 1 2 part number marking lot number 1pin mark b d 8 downloaded from: http:///
20 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn physical dimension, tape and reel information package name hson8 downloaded from: http:///
21 / 21 tsz02201-0q3q0nz00360-1-2 ? 2014 rohm co., ltd. all rights reserved. 17. feb.2015 rev.002 www.rohm.com tsz22111 ? 15 ? 001 bd8312hfn re vision history date revision changes 26 .nov.2014 001 new release 17.feb.2015 002 correction of the writing. downloaded from: http:///
datasheet d a t a s h e e t notice-pga-e rev.001 ? 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 (pd) depending on ambient temper ature (ta). when used in seal ed area, confirm the actual ambient 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.001 ? 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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