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1/17 www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. single-chip type with built-in fet switching regulator series output 2a or more high-efficiency step-down switching regulator with built-in power mosfet bd9134muv description rohm?s high efficiency step-down switching regulator bd9134muv is a power supply designed to produce 3.3 volts from 5 volts power supply line. offers high efficiency with our original pulse skip control technology and synchronous rectifier. employs a current mode control system to provide fa ster transient response to sudden change in load. features 1) offers fast transient response with current mode pwm control system. 2) offers highly efficiency for all load range with synchronous rectifier (nch/nch fet) and sllm tm (simple light load mode) 3) incorporates soft-start function. 4) incorporates thermal protection and uvlo functions. 5) incorporates short-current protec tion circuit with time delay function. 6) incorporates shutdown function icc=0 a(typ.) 7) employs small surface mount package : vqfn020v4040 use power supply for lsi including dsp, micro computer and asic absolute maximu m rating (ta=25 ) parameter symbol limits unit v cc voltage v cc -0.3 +7 * 1 v pv cc voltage pv cc -0.3 +7 * 1 v bst voltage v bst -0.3 +13 v bst_sw voltage v bst - sw -0.3 +7 v en voltage v en -0.3 +7 v sw,ith voltage v sw , v ith -0.3 +7 v power dissipation 1 pd1 0.34 * 2 w power dissipation 2 pd2 0.70 * 3 w power dissipation 3 pd3 1.21 * 4 w power dissipation 4 pd4 3.56 * 5 w operating temperature range topr -40 +105 storage temperature range tstg -55 +150 maximum junction temperature tj +150 *1 pd should not be exceeded. *2 ic only *3 1-layer. mounted on a 74.2mm 74.2mm 1.6mm glass-epoxy board, occupied area by copper foil : 10.29mm 2 *4 4-layer. mounted on a 74.2mm 74.2mm 1.6mm glass-epoxy board, occupied area by copper foil : 10.29mm 2 , in each layers *5 4-layer. mounted on a 74.2mm 74.2mm 1.6mm glass-epoxy board, occupied area by copper foil : 5505mm 2 , in each layers operating conditions (ta=-40 +105 ) parameter symbol limits unit min. typ. max. power supply voltage v cc 4.5 5 5.5 v pv cc 4.5 5 5.5 v en voltage ven 0 - 5.5 v output current i sw - - 3.0* 6 a *6 pd should not be exceeded. no.09027ebt15
technical note 2/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. electrical characteristics (ta=25 v cc =pv cc =5v, en=v cc , unless otherwise specified.) parameter symbol limits unit conditions min. typ. max. standby current i stb - 0 10 a en=gnd active current i cc - 250 500 a en low voltage v enl - gnd 0.8 v standby mode en high voltage v enh 2.0 vcc - v active mode en input current i en - 1 10 a v en =5v oscillation frequency f osc 0.8 1 1.2 mhz high side fet on resistance r onh - 82 115 m ? pv cc =5v low side fet on resistance r onl - 70 98 m ? pv cc =5v output voltage v out 3.25 3.3 3.35 v ith si nk current i thsi 10 18 - a v out =4.1v ith s ource c urrent i thso 10 18 - a v out =2.5v uvlo threshold voltage v uvlo1 3.6 3.8 4.0 v v cc =5v 0v uvlo release voltage v uvlo2 3.65 3.9 4.2 v v cc =0v 5v soft start time t ss 2.5 5 10 ms timer latch time t latch 0.5 1 2 ms output short circuit threshold voltage v scp - 1.65 2.4 v v out =3.3v 0v
technical note 3/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. block diagram, application circuit bd9134muv pin no. & function table pin no. pin name function pin no. pin name function 1 sw sw pin 11 gnd ground 2 sw sw pin 12 vout output voltage detect pin 3 sw sw pin 13 ith gmamp output pin/connected phase compensation capacitor 4 sw sw pin 14 n.c. non connection 5 sw sw pin 15 n.c. non connection 6 pvcc highside fet source pin 16 n.c. non connection 7 pvcc highside fet source pin 17 en enable pin(high active 8 pvcc highside fet source pin 18 pgnd lowside fet source pin 9 bst bootstrapped voltage input pin 19 pgnd lowside fet source pin 10 vcc vcc power supply input pin 20 pgnd lowside fet source pin 2.10.1 c0.2 0.5 1.0 15 6 10 11 15 16 20 4.0 4.0 2.10.1 0.30.1 0.25 +0.05 -0.04 0.01 +0.03 -0.01 0.10.07 1.0max. (0.21) 0.08 s s fig.2 bd9134muv block diagram fig.1 bd9134muv top view d9134 lot no. vqfn020v4040(unit : mm) output pgnd gnd gm amp r s q osc uvlo tsd + v cc v cc clk slope en current comp soft start current sense/ protect + driver logic + vref ith vout r ith c ith pv cc sw pv cc bst v cc 5v input scp
technical note 4/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. 0.0 1.0 2.0 3.0 4.0 012345678 output current:i out [a] output voltage:vout[v] v out =3.3v vcc=5v ta = 2 5 characteristics data fig.3 vcc - vout fig.4 ven - vout fig.5 iout - vout fig. 6 ta - v out fig.7 efficiency fig.8 ta - fosc fig.9 ta ? r onn , r onp fig.10 fig.11 ta - v en fig.11 ta - icc 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 -40 -20 0 20 40 60 80 100 temperature:ta[ ] en voltage:ven[v] vcc=5v 0 50 100 150 200 250 300 350 400 -40 -20 0 20 40 60 80 100 temperature:ta[ ] circuit current:i cc [ a] vcc=5v 0.0 1.0 2.0 3.0 4.0 012 345 input voltage:v cc [v] output voltage:vout[v] v out =3.3v ta = 2 5 io=3a 3.25 3.26 3.27 3.28 3.29 3.30 3.31 3.32 3.33 3.34 3.35 -40-200 20406080100 temperature:ta[ ] output voltage:vout[v] vcc=5v io=0a v out =3.3v 0 200 400 600 800 1000 1200 -40-20 0 2040 6080100 temperature:ta[ ] frequency:f osc [mhz] vcc=5v 0.0 1.0 2.0 3.0 4.0 5.0 012345 en voltage:ven[v] output voltage:vout[v] vcc=5v ta = 2 5 io=0a v out =3.3v 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 10000 output current:i out [ma] efficiency: [%] vcc=5v ta = 2 5 vout=3.3v 0 25 50 75 100 125 150 -40 -20 0 20 40 60 80 100 temperature:ta[ ] on resistance:r on [ ] vcc=5v high side low side
technical note 5/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. characteristics data fig.12 vcc - fosc fig.13 soft start waveform fig.14 sw waveform io=10ma fig.15 sw waveform io=3a fig. 16 transient response io=1 3a(10 s) fig.17 transient response io=3 1a(10 s) v out i out vcc=5 v ta = 2 5 v out =3.3v v out i out vcc=5v t a =2 5 v out =3.3v sw v out vcc=5v ta = 25 sllm tm vout=3.3v sw v out vcc=5v ta = 2 5 pwm vout = 3.3v vout=3.3v vcc=5v ta = 2 5 io = 0a vcc=pvcc = en vout 0.7 0.8 0.9 1 1.1 4.5 4.75 5 5.25 5.5 input voltage:v cc [v] frequency:f osc [mhz] ta = 2 5
technical note 6/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. information on advantages advantage 1 offers fast transient response with current mode control system. voltage drop due to sudden change in load was reduced by about 50%. fig.18 comparison of transient response advantage 2 offers high efficiency for all load range. ? for lighter load: utilizes the current mode control mode called sllm tm for lighter load, which reduces various dissipation such as switching dissipation (p sw ), gate charge/discharge dissipation, esr dissipation of output capacitor (p esr ) and on-resistance dissipation (p ron ) that may otherwise cause degradation in efficiency for lighter load. achieves efficiency improvement for lighter load. ? for heavier load: utilizes the synchronous rectifying mode and the low on-re sistance mos fets incorporated as power transistor. on resistance of highside mos fet : 82m ? (typ.) on resistance of lowside mos fet : 70m ? (typ.) achieves efficiency improvement for heavier load. offers high efficiency for all load rang e with the improvements mentioned above. advantage 3 ? supplied in smaller package due to small-sized power mos fet incorporated. reduces a mounting area required. fig.20 example application fig.19 efficiency bd9134muv (load response i o =1a 3a) ? output capacitor co required for current mode control: 22 f ceramic capacitor ? inductance l required for the oper ating frequency of 1 mhz: 2.2 h inductor ? incorporates fet + boot strap diode 0.001 0.01 0.1 1 0 50 100 pwm sllm tm inprovement by sllm tm system improvement by synchronous rectifier efficiency [%] output current io[a] v cc conventional product (load response i o =1a 3a) v out i out 572mv v out i out 328mv output pgnd gnd gm amp r s q osc uvlo tsd + vcc clk slope en current comp soft start current sense/ protect + driver logic + vref ith vout r ith c ith pvcc sw pvcc bst vcc 3.3v input scp 15mm 20mm r 2 c ith c f co l r 1 r ith rf c bst c in
technical note 7/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. operation bd9134muv is a synchronous rectifying step-down switching regu lator that achieves faster transient response by employing current mode pwm control system. it utiliz es switching operation in pwm (pulse width modulation) mode for heavier load, while it utilizes sllm tm (simple light load mode) operation for lighter load to improve efficiency. synchronous rectifier it does not require the power to be dissipated by a rectifier externally connected to a conventional dc/dc converter ic, and its p.n junction shoot-through protection circuit limits the shoot-through current during o peration, by which the power dissipation of the set is reduced. current mode pwm control synthesizes a pwm control signal with a inductor current feedback loop added to the voltage feedback. ? pwm (pulse width modulation) control the oscillation frequency for pwm is 1 mhz. set signal form osc turns on a highside mos fet (while a lowside mos fet is turned off), and an inductor current i l increases. the current comparator (c urrent comp) receives two signals, a current feedback control signal (sense: voltage converted from i l ) and a voltage feedback control signal (fb), and issues a reset signal if both input signals are identical to each other, and turns off the highside mos fet (while a lowside mos fet is turned on) for the rest of the fixed period. the pwm control repeat this operation. ?sllm tm (simple light load mode) control when the control mode is shifted from pwm for heavier load to the one for lighter load or vise versa, the switching pulse is designed to turn off with the device held operated in norma l pwm control loop, which allows linear operation without voltage drop or deterioration in transient response during the mo de switching from light load to heavy load or vise versa. although the pwm control loop continues to operate with a set signal from osc and a reset signal from current comp, it is so designed that the reset signal is held issued if shifted to the light load mode, with which the switching is tuned off and the switching pulses are thinned out under control. activating the switch ing intermittently reduces the switching dissipation and improves the efficiency. fig.21 diagram of current mode pwm control osc level shift driver logic rq s i l sw ith current comp gm amp. set reset fb load sense v out v out fi g. 22 pwm sw i tc hi ng t i m i ng c h art fig.23 sllm tm switching timing chart curren t comp set reset sw v out pvcc gnd gnd gnd i l (ave) v out (ave) sense fb curren t comp set reset sw v out pvcc gnd gnd gnd 0a v out (ave) sense fb i l not switching i l
technical note 8/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. description of operations ? soft-start function en terminal shifted to ?high? activates a soft-starter to gradually establish the output voltage with the current limited durin g startup, by which it is possible to prevent an ov ershoot of output voltage and an inrush current. ? shutdown function with en terminal shifted to ?low?, the device turns to standby mode, and all the function blocks including reference voltage circuit, internal oscillator and drivers are turn ed to off. circuit current during standby is 0 a (typ.). ? uvlo function detects whether the input voltage sufficient to secure the output voltage of this ic is supplied. and the hysteresis width of 100mv (typ.) is provided to prevent output chattering. fig.24 soft start, shutdown, uvlo timing chart hysteresis 50mv ts s ts s ts s soft start standby mode operating mode standby mode operating mode standby mode operating mode standby mode uvlo en uvlo uvlo v cc en v ou t
technical note 9/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. ? short-current protection circuit with time delay function turns off the output to protect the ic fr om breakdown when the incorporated current limiter is activated continuously for the fixed time(t latch ) or more. the output thus held tuned off may be recovered by restarting en or by re-unlocking uvlo. fig.25 short-current protection circuit with time delay timing chart switching regulator efficiency efficiency ? may be expressed by the equation shown below: efficiency may be improved by reducing the swit ching regulator power dissipation factors p d as follows: dissipation factors: 1) on resistance dissipation of inductor and fet pd(i 2 r) 2) gate charge/discharge dissipation pd(gate) 3) switching dissipation pd(sw) 4) esr dissipation of capacitor pd(esr) 5) operating current dissipation of ic pd(ic) 1)pd(i 2 r)=i out 2 (r coil +r on ) (r coil [ ] dc resistance of inductor, r on [ ] on resistance of fet, i out [a] output current.) 2)pd(gate)=cgs f v (cgs[f] gate capacitance of fet f[h] switching frequency v[v] gate driving voltage of fet) 4)pd(esr)=i rms 2 esr (i rms [a] ripple current of capacitoresr[ ] equivalent series resistance.) 5)pd(ic)=vin i cc (i cc [a] circuit current.) = v out i out vin iin 100[%]= p out pin 100[%]= p out p out +p d 100[%] vin 2 c rss i out f i drive 3)pd(sw)= (c rss [f] reverse transfer capacitance of fet i drive [a] peak current of gate.) 1/2v out 1mse c output voltage off latch output current in non-control output current in control by limit value (with fall of the output voltage, limit value goes down) en timer latch en standby mode operated mode standby mode operated mode en v out limi t i l until output voltage goes up the half of vo or over, timer latch is not operated. (no timer latch, only limit to the output current)
technical note 10/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. consideration on permissible dissipation and heat generation as this ic functions with high efficien cy without significant heat generation in most applications, no special consideration is needed on permissible dissipation or heat generation. in case of extreme conditions, however, including lower input voltage, higher output voltage, heavier load, and/or higher temperature, the permissible di ssipation and/or heat generation must be carefully considered. for dissipation, only conduction losses due to dc resistance of inductor and on resistance of fet are considered. because the conduction losses are considered to play the leading role among other dissipation mentioned above including gate charge/discharge dissipation and switching dissipation. p=i out 2 r on r on =d r onp +(1-d)r onn d on duty (=v out /v cc ) r onh on resistance of highside mos fet r onl on resistance of lowside mos fet i out output current if v cc =5v, v out =3.3v, r onh =82m , r onl =70m i out =3a, for example, d=v out /v cc =3.3/5.0=0.66 r on =0.66 0.082+(1-0.66) 0.07 =0.05412+0.0238 =0.07792[ ] p=3 2 0.07792 0.70128[w] as r onh is greater than r onl in this ic, the dissipation increases as the on duty becomes greater. with the consideration on the dissipation as above, the rmal design must be carried out with sufficient margin allowed. fig.26 thermal derating curve (vqfn020v4040) power dissipation:pd [w] ambient temperature:ta [ ] 0 25 50 75 100 125 150 0 2.0 3.0 4.0 1.21w 3.56w 1.0 0.70w 0.34w 4 layers (copper foil area : 5505mm 2 ) copper foil in each layers. j-a=35.1 /w 4 layers (copper foil area : 10.29m 2 ) copper foil in each layers. j-a=103.3 /w 4 layers (copper foil area : 10.29m 2 ) j-a=178.6 /w ic onl y . 105
technical note 11/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. selection of components externally connected 1. selection of inductor (l) *current exceeding the current rating of the inductor results in magnetic saturation of the inductor, which decreases efficienc y. the inductor must be selected allowing sufficient margin with which the peak current may not exceed its current rating. if v cc =5.0v, v out =3.3v, f=1mhz, i l =0.2 3a=0.6a, for example,(bd9134muv) *select the inductor of low resistance component (such as dcr and acr) to minimize dissipation in the inductor for better efficiency. 2. selection of output capacitor (c o ) the inductance significantly depe nds on output ripple current. a s seen in the equation (1), the ripple current decreases as the inductor and/or switching frequency increases. i l = (v cc -v out )v out l v cc f [a] ??? ( 1 ) a ppropriate ripple current at output should be 20% more or less of the maximum out p ut current. i l =0.2 i out max. [a] ???(2) l= (v cc -v out )v out i l v cc f [h] ??? ( 3 ) (i l : output ripple current, and f: switching frequency) output capacitor should be selected with the consideration on the stability region and the equivalent series resistance re quired to smooth ripple voltage. output ripple voltage is determined by the equation (4) v out = i l esr [v]??? (4) (i l : output ripple current, esr: equivalent series resistance of output capacitor) rating of the capacitor should be determined allowing sufficient margin against output voltage. a 22 f to 100 f ceramic capacitor is recommended. less esr allows reduction in output ripple voltage. fig.28 output capacitor ( 5-3.3 ) 3.3 0.6 5 1m l= =1.87 2.2[ h] i l v out fig.27 output ripple current i l v cc il l co v cc l co v out esr
technical note 12/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. 3. selection of input capacitor (cin) a low esr 22 f/10v ceramic capacitor is recommended to reduce esr di ssipation of input capaci tor for better efficiency. 4. determination of rith, cith that works as a phase compensator as the current mode control is designed to limit a inductor current, a pole (phase l ag) appears in the low frequency area due to a cr filter consisting of a output capacitor and a load resistance, while a zero (phase lead) appears in the high frequency area due to the output capacitor and its esr. so, the phases are easily compensated by adding a zero to the power amplifier output with c and r as described below to cancel a pole at the power amplifier. input capacitor to select must be a low esr capacitor of the capacitance sufficient to cope with high ripple current to prevent high transient voltage. the ripple current irms is given by the equation (5): i rms =i out v out ( v cc -v out ) v cc [a] ??? ( 5 ) when vcc=2 v out , i rms = i out 2 < worst case > i rms(max.) i rms =3 3.3 ( 5-3.3 ) 5 =1.42 [ a rms ] gain [db] phase [deg] fig.30 open loop gain cha r acteristics a 0 0 -90 a 0 0 -90 fz(amp.) fig.31 error amp phase compensation characteristics fp= 2 r o c o 1 fz (esr) = 2 e sr c o 1 pole at power amplifie r when the output current decreases, the load resistance ro increases and the pole frequency lowers. fp (min.) = 2 r omax. c o 1 [hz] with lighter load fp (max.) = 2 r omin. c o 1 [hz] with heavier load zero at power amplifie r fz (amp.) = 2 r ith c ith 1 fig.29 input capacitor fp(min.) fp(max.) fz(esr) i out min. i out max. gain [db] phase [deg] v out v cc l co cin increasing capacitance of the out put capacitor lowers the pole frequency while the zero frequency does not change. (this is because when the capacitance is doubled, the capacito r esr reduces to half.) if v cc =5v, v out =3.3v, and i outmax.= 3a, (bd9134muv)
technical note 13/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. stable feedback loop may be achieved by canceling the pole fp (mi n.) produced by the output ca pacitor and the load resistance with cr zero correction by the error amplifier. fig.32 typical application fz(amp.)= fp(min.) 2 r ith c ith 1 = 2 r omax. c o 1 gnd,pgnd sw pv cc en a dj ith v cc v out cin r ith c ith l esr c o r o v out c bst v cc c f r f
technical note 14/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. bd9134muv cautions on pc board layout fig.33 layout diagram lay out the input ceramic capacitor cin closer to the pins pvcc and pgnd, and the output capacitor co closer to the pin pgnd. lay out cith and rith between the pi ns ith and gnd as neat as possible with least necessary wiring. vqfn020v4040 (bd9134muv) has thermal pad on the reverse of the package. the package thermal performance may be enhanced by bonding the pad to gnd plane which take a large area of pcb. recommended components lists on above application symbol part value manufacturer series l coil 2.0uh sumida cdr6d28mnp-2r0nc 2.2uh sumida cdr6d26np-2r2nc c in ceramic capacitor 22uf murata grm32eb11a226ke20 c o ceramic capacitor 22uf murata grm31cb30j226ke18 c ith ceramic capacitor 1500pf murata grm18 serise r ith resistance 5.1k rohm mcr03 serise cf ceramic capacitor 1000 pf murata grm18 serise rf resistance 10 rohm mcr03 serise *the parts list presented above is an example of recommend ed parts. although the parts ar e sound, actual circuit characteristics should be checked on your application carefully before use. be sure to allow sufficient margins to accommodate variations between external devices and this ic when employing the depicted circuit with other circuit constants modified. both static and transient characteristics should be considered in establishing these margins. when switching noise is substantial and may im pact the system, a low pass filter shou ld be inserted between the vcc and pvcc pins, and a schottky barrier diode or snubber established between the sw and pgnd pins.
technical note 15/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. i/o equivalence circuit fig.34 i/o equivalence circuit en ? en pin ? sw pin pv cc sw pv cc pv cc ith ? ith pin v cc ? vout pin pv cc bst ? bst pin pv cc sw vout
technical note 16/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. notes for use 1. absolute ma ximum ratings while utmost care is taken to quality control of this pr oduct, any application that may exceed some of the absolute maximum ratings including the voltage applied and the operat ing temperature range may result in breakage. if broken, short-mode or open-mode may not be identif ied. so if it is expected to encounter with special mode that may exceed the absolute maximum ratings, it is requested to take necessary sa fety measures physically including insertion of fuses. 2. electrical potential at gnd gnd must be designed to have the lowest elec trical potential in any operating conditions. 3. short-circuiting between terminals, and mismounting when mounting to pc board, care must be taken to avoid mistak e in its orientation and alignment. failure to do so may result in ic breakdown. short-circuiting due to forei gn matters entered between output terminals, or between output and power supply or gnd may also cause breakdown. 4. thermal shutdown protection circuit thermal shutdown protection circuit is the circuit designed to isolate the ic from thermal runaway, and not intended to protect and guarantee the ic. so, the ic the thermal shutdown protection circui t of which is once activated should not be used thereafter for any operation originally intended. 5. inspection with the ic set to a pc board if a capacitor must be connected to the pin of lower impeda nce during inspection with the ic set to a pc board, the capacitor must be discharged after each process to avoid stress to the ic. for electrostatic protection, provide proper grounding to assembling processes with special care taken in handling and storage. when connecting to jigs in the inspection process, be sure to turn off the power supply before it is connected and removed. 6. input to ic terminals this is a monolithic ic with p + isolation between p-substrate and each element as illustrated below. this p-layer and the n-layer of each element form a p-n junction, and various parasitic element are formed. if a resistor is joined to a transistor terminal as shown in fig 35. p-n junction works as a parasitic diode if t he following relationship is satisfied; gnd>terminal a (at resistor side), or gnd>terminal b (at transistor side); and if gnd>terminal b (at npn transistor side), a parasitic npn transistor is activated by n-layer of ot her element adjacent to the above-mentioned parasitic diode. the structure of the ic inevitably forms parasitic elements, the activation of which may cause interference among circuits, and/or malfunctions contributing to breakdown . it is therefore requested to take care not to use the device in such manner that the voltage lowe r than gnd (at p-substrate) may be applied to the input terminal, which may result in activation of parasitic elements. fig.35 simplified structure of monorisic ic 7. ground wiring pattern if small-signal gnd and large-current gnd are provided, it will be recommended to separate the large-current gnd pattern from the small-signal gnd pattern and establish a si ngle ground at the reference poi nt of the set pcb so that resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of the small-signal gnd. pay attention not to cause fluctuations in the gnd wiring pattern of external parts as well. 8 . selection of inductor it is recommended to use an inductor with a series resistance element (dcr) 0.1 or less. especially, note that use of a high dcr inductor will cause an inductor loss, resulting in decr eased output voltage. should this condition continue for a specified period (soft start time + timer latch time), output short circuit protecti on will be activated and output will be lat ched off. when using an inductor over 0.1 , be careful to ensure adequate margins for variation between external devices and this ic, including transient as well as static characteristics. furthermore, in any case, it is recommended to start up the output with en after supply voltage is within operation range. resistor transistor (npn) n n n p + p + p p substrate gnd parasitic element pin a n n p + p + p p substrate gnd parasitic element pin b c b e n gnd pin a p aras iti c element pin b other adjacent elements e b c gnd p aras iti c element
technical note 17/17 bd9134muv www.rohm.com 2009.09 - rev.b c 2009 rohm co., ltd. all rights reserved. ordering part number b d 9 1 3 4 m u v - e 2 part no. part no. package muv: vqfn020v4040 packaging and forming specification e2: embossed tape and reel ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tape quantity direction of feed the direction is the 1pin of product is at the upper left when you hold reel on the left hand and you pull out the tape on the right hand 2500pcs e2 () direction of feed reel 1pin (unit : mm) vqfn020v4040 2.10.1 1 15 11 20 16 5 10 6 0.5 1.0 0.25 +0.05 - 0.04 2.10.1 0.40.1 c0.2 1.0max 0.02 +0.03 - 0.02 (0.22) 4.00.1 4.00.1 1pin mark 0.08 s s
r0039 a www.rohm.com ? 2009 rohm co., ltd. all rights reserved. notice rohm customer support system http://www.rohm.com/contact/ thank you for your accessing to rohm product informations. more detail product informations and catalogs are available, please contact us. notes no copying or reproduction of this document, in part or in whole, is permitted without the consent of rohm co.,ltd. the content specied herein is subject to change for improvement without notice. the content specied herein is for the purpose of introducing rohm's products (hereinafter "products"). if you wish to use any such product, please be sure to refer to the specications, which can be obtained from rohm upon request. examples of application circuits, circuit constants and any other information contained herein illustrate the standard usage and operations of the products. the peripheral conditions must be taken into account when designing circuits for mass production. great care was taken in ensuring the accuracy of the information specied in this document. however, should you incur any damage arising from any inaccuracy or misprint of such information, rohm shall bear no responsibility for such damage. the technical information specied herein is intended only to show the typical functions of and examples of application circuits for the products. rohm does not grant you, explicitly or implicitly, any license to use or exercise intellectual property or other rights held by rohm and other parties. rohm shall bear no responsibility whatsoever for any dispute arising from the use of such technical information. the products specied in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, ofce-automation equipment, commu- nication devices, electronic appliances and amusement devices). the products specied in this document are not designed to be radiation tolerant. while rohm always makes efforts to enhance the quality and reliability of its products, a product may fail or malfunction for a variety of reasons. please be sure to implement in your equipment using the products safety measures to guard against the possibility of physical injury, re or any other damage caused in the event of the failure of any product, such as derating, redundancy, re control and fail-safe designs. rohm shall bear no responsibility whatsoever for your use of any product outside of the prescribed scope or not in accordance with the instruction manual. the products are not designed or manufactured to be used with any equipment, device or system which requires an extremely high level of reliability the failure or malfunction of which may result in a direct threat to human life or create a risk of human injury (such as a medical instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuel-controller or other safety device). rohm shall bear no responsibility in any way for use of any of the products for the above special purposes. if a product is intended to be used for any such special purpose, please contact a rohm sales representative before purchasing. if you intend to export or ship overseas any product or technology specied herein that may be controlled under the foreign exchange and the foreign trade law, you will be required to obtain a license or permit under the law.

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