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1/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. single-chip type with built-in fet type switching regulators flexible step-down switching regulator with built-in power mosfet bd8649efv description the bd8649efv is a synchronous step-down switching regulator that integrates 2 low resi stances n-channel mosfets. it achieves 3a continuous output curr ent over a wide input supply range. current mode operation provides fast transie nt response and easy phase compensation. feature 1) synchronous rectification wi th built-in fet type dc/dc converter 2) 3.0a output current 3) range of operation power-supply voltage 4.5v 18v 4) reference voltage fb 0.8v1% 5) programmable frequency 100khz 600khz 6) over current protection function 7) thermal shutdown function 8) under voltage protection 9) soft start time out functi on / soft start delay circuit 10) programmable offlatch time applications fpd,dvd,hdd recorder,stb,amusement,other absolute maximum rating (ta=25 ) parameter symbol ratings unit input supply voltage v in 20 v boot terminal voltage v boot 28 v en terminal voltage v en gnd-0.3 v in +0.3 v input terminal voltage v inp *1 gnd-0.3 7 v sw terminal voltage v sw gnd-0.3 v in +0.3 v output current i out 3.5 *2 a power dissipation pd 3.2 *2 w operating temperature topr -20 85 storage temperature ts t g -55 150 *1 v inp application terminal: ss/delay, fb, fc, rt, pset *2 (70mm70mm, thickness 1.6mm, and four layer glass epoxy substrates)when mounting substrate and the package back exposure part are connected with solder operating at higher than ta=25 , 25.6mw shall be reduced per 1 operation condition parameter symbol ratings unit min. typ. max. input supply voltage v in 4.5 - 18.0 v output current i out - - 3.0 a * this product is not designed for protection against radioactive rays. no.10027eat45
technical note 2/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv product number lot no. bd8649 1 pin electrical characteristic (unless otherwise noted ta=25 , v in =12v, v en = 3v) parameter symbol limits unit condition min. typ. max. v in supply current (operating) i q_active - 1.5 2.5 ma v fb = 0.75v v in supply current (standby) i q_stby - 0.8 1.2 ma v en = 0v reference voltage (vref) v fb 0.792 0.800 0.808 v fb-fc short oscillation frequency f osc 270 300 330 khz r rt = 56k ? high side fet on resistance r hfet - 110 160 m ? i sw = -1a low side fet on resistance r lfet - 110 160 m ? i sw = 1a uvlo voltage v uvlo 3.8 4.0 4.2 v v in sweep sw leak current i lsw - 0 5 a v en = 0v en terminal h threshold voltage v enh 1.6 - - v en terminal l threshold voltage v enl - - 0.4 v ss/delay terminal source current i ssso 2.8 4.0 5.2 a v ss = 1v ss/delay ? fb offset voltage v ssfbost 450 600 750 mv v ss = 1v pset terminal source current i pset 3.0 5.0 7.0 a v pset = 2v pset terminal threshold voltage v pset 0.8 1.0 1.2 v v fb :fb terminal voltage,v en :en terminal voltage,v ss :ss/delay terminal voltage, v pset :pset terminal voltage, r rt :rt resistor current capability should not exceed pd. package outline dimension htssop-b20 (unit: mm)
technical note 3/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 -20-51025 40557085 ta [] iss[a] 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 -20 -5 10 25 40 55 70 85 ta [] vfbfc[v] 260 270 280 290 300 310 320 330 340 -20-5102540557085 ta [] fs w[khz ] reference data 0.790 0.795 0.800 0.805 0.810 4 6 8 1012141618 vin[v] vfbfc[v] vin=12v ta = 2 5 fig.1 reference voltage ? temperature characteristic fig.2 reference voltage ? vin characteristic 0 40 80 120 160 200 240 280 320 4 6 8 1012 1416 18 vin[v] vin_sw[m] 0 40 80 120 160 200 240 280 320 4 6 8 101214 1618 vin[v] sw_pgnd[m] fig.9 hi side fet on_r - vin characteristic fig.10 low side fet on_r ? vin characteristic ta = 2 5 ta = 2 5 0 40 80 120 160 200 240 280 320 -20-5 10254055 7085 ta [] vin_sw[m] 0 40 80 120 160 200 240 280 320 -20-5102540557085 ta [] sw_pgnd[m] fig.7 hi side fet on_r - temperature characteristic fig.8 low side fet on_r - temperature characteristic vin=12v vin=12v 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 4 6 8 10 12141618 vin[v] icc[ma] vin=12v ta = 2 5 fig.5 ss/delay charge current - temperature characteristic fig.6 circuit current ? vin characteristic 260 270 280 290 300 310 320 330 340 4 6 8 1012141618 vin[v] fsw[khz ] fig.3 frequency ? temperature characteristic vin=12v ta = 2 5 fig.4 frequency ? vin characteristic vfb and fc [v] vfb and fc [v]
technical note 4/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv block diagram 1 2 3 4 5 6 7 osc protect time en pwm control 20 19 18 17 16 15 14 current det fc rt pset en nc nc gnd nc boot sw sw sw vout 5v ss/delay fb softstart/delay 8 9 10 13 12 11 vin vin vin pgnd pgnd pgnd fig.11 block diagram pin assignment no. symbol description no. symbol description 1 fb feedback terminal 11 pgnd power gnd terminal 2 fc phase amends terminal 12 pgnd power gnd terminal 3 rt frequency adjustment resistance connection terminal 13 pgnd power gnd terminal 4 pset adjust off latch time termi nal 14 sw switchi ng output terminal 5 en enable input 15 sw switching output terminal 6 nc - 16 sw switching output terminal 7 nc - 17 boot boot strap terminal 8 vin power supply input terminal 18 nc - 9 vin power supply input terminal 19 ss/delay soft start adjustment capacity connection terminal 10 vin power supply input terminal 20 gnd signal gnd terminal
technical note 5/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv operation description 1 enable control the device can be controlled on/off by en terminal (5 pin) voltage. an internal circuit starts when ven reaches 1.6v. when standing up of vin is too steep (1msec or less), a defect ive start might be caused according to the state of pascon between gnd substrate pattern and power supply-when the termina l en is short-circuited to the terminal vin and it is used. v en 0 v ss 0 v ssclm v ssth v o 0 t ss v enh v enl en terminal ss terminal output setting voltage fig.12 on/off transition wave form in en controlling 2 soft start time set function as for bd8649efv, output can do soft start without overshoot by charging soft start capacity (c ss ) connected between ss/delay (19 pin) and gnd (20 pin) terminal. also, soft start time (tss) can be se t by setting soft start capacity (c ss ) arbitrarily. (refer to 5-2 soft start time setting method) 3 osc oscillation frequency setting function the output oscillation frequency can be set by connecting resistance between terminal rt (3 pin) and gnd (range = 100khz ? 600khz) the relation between rt terminal resistance and the oscillation frequency follows fig.13. 10 100 1000 10000 1 10 100 1000 rt[k] sw[khz] fig.13 oscillation frequency setting by rt resistance
technical note 6/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv protection function protection circuit is effective for destruction prevention due to accident so that avoid usin g under continuous protection operation. 1 low voltage protection function (lvp) the voltage of the terminal fb (1pin) is compared with internal reference voltage vref. if fb terminal voltage falls below v lvp (= vref -120mv) and the state continues, output changes to low voltage and the state is fixed. table 1 output low voltage protection function en terminal ss terminal fb terminal low voltage protection function low voltage protection operation >v enh >1.4v(typ) v lvp effective on v lvp off <1.4v(typ) - invalidity off v enh >1.4v(typ) v ovp effective on v ovp off <1.4v(typ) - invalidity off technical note 7/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv 3 under voltage lock out protection (uvlo) as for bd8649efv, the power-supply voltage decr ease detection protection circuit is built in. it the input voltage decrease below the uvlo voltage (4.0v ty p), the device state changes to the standby mode (moreover, to prevent the chattering of the output) hysteresis width of 300mv(typ) has been installed in the uvlo cancel voltage. 4 rt terminal open/short protection function (rto/rts) rt terminal opening/short protection function prevents the clock from abnormal oscillation. if rt terminal open/short protection function is detected, output voltage changes to low level and is fixed. 5 soft start time-out function if vss doesn't exceed vssth within 75msec (typ) since a so ft start began, bd8649efv controls an off latch. vo is fixed in a low level. v ssth 0v ss terminal about 64msec typ fig.15 soft start time-out 6 thermal shut down function thermal shut down circuit (tsd circuit) is built into bd864 9efv. when the temperature of t he chip exceeds tjmax=175, the dc/dc converter is fixed in a low voltage. tsd function is aimed to shut down ic from thermal re ckless driving under an abnormal state to exceed tjmax=150. it aims at neither protection nor the guar antee of the set. therefore, please do not use this function to protect the set. 7 over current protection function the over current protection function has been achieved by limiting the current that flows on high side mosfet. the current is controlled in every one cy cle of the switching frequency. when an ab normal state continues, the output is fixed in a low level. 8 error detection (off latch) release method bd8649efv enters the state of an off latc h when the protection function operates. to release the off latch state, vin terminal voltage should be changed to less than uvlo level (=4.0v [typ] ) once time.
technical note 8/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv v ssth(=1.4v[typ]) venh 0v 0v 0v t vo tw en (=50sec) v ost(=0.6v[typ]) en terminal ss terminal output setting voltage external parts setting method 1 output voltage setting method the output voltage can be arbitrarily set by external resistance. vref r2 r2)(r1 vo ? ? please select the constant of r1 and r2 by this expression. please select the current that flows to r1 and r2 to become much smaller than output current. fb r1 r2 vo vref=0.8v fig.16 output voltage setting circuit 2 soft start time setting method bd8649efv can soft start without overshoot because of a charge current to the soft start capacitance (css). the soft start time can be set by co nnecting soft start capacity (css). when the en terminal voltage is set vin_en or more, the charge to the capacity between ss/delay and gnd terminal is begun. the output voltage becomes soft start in proportion to a ss/delay terminal voltage rising. when the ss/delay terminal voltage exceeds vssth, the output voltage is fixed in a setting value. please set soft start time (tss) in 1msec-52.5msec. fig.17 soft start tw en spec min. typ. max. 35sec 50sec 75sec )a 4(i c)v(v )a 4(i c)v6.0(v )s 50(twt ss ss ost ssth ss ss ost en vo ? ?? ? ? ?? ???
technical note 9/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv i l i l 3 selection of inductor (l) please select the value of the inductor according to the following expressions. f v i v ) v (v l in l out out in ? ? ? ? ? S [h] ( S il: output ripple current , f: switching frequency) please have and select an enough margin so that the current peak should not exceed the ratings current value of the inductor. 4 selection of input capacitor (cin) please use a low esr input capacitor which can be used with high voltage and ripple current to prevent a big transition voltage. please put on the input capacitor near side by vin-pgnd. 5 selection of diode please have and set the margin enough to the current rating of the diode for the maximum load current. moreover, please similarly have and set the margin enough to a ratings reverse-voltage for the maximum input voltage. c1 r1 fb fc fig.19 phase amends part external circuit chart 6 offlatch time setting method if it continues abnormal state, bd8649efv output become low voltage and state is fixed. in this case, the offlatch time can be set by connecting capacitor between pset and gnd. please select the value of offlatch time according to the following expression. please set offlatch time in 200sec 5msec. t tm = c pset [sec] ??? (11) i pset (5a typ) to release the off latch state, en or vin terminal voltage should be changed to low level once time. fig.18 current of output ripple
technical note 10/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv typical application condition vout = 3.3v fosc = 550khz off latch time = 500sec 1 2 3 4 5 6 7 osc protect time en pwm control 20 19 18 17 16 15 14 current det fc rt pset en nc nc gnd nc boot sw sw sw vout 5v ss/delay fb softstart/delay 8 9 10 13 12 11 vin vin vin pgnd pgnd pgnd 47k open 15k 2200p 22k 27k 2000p 22 22?2pcs 4.7 0.1 0.033 fig.20 typical application
technical note 11/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv i/o equivalence circuit 1pin(fb) 2pin(fc) 3pin(rt) 4pin(pset) 5pin(en) 14,15,16pin(sw) 17pin(boot) 19pin(ss/delay) vin fb 50k ? pset gnd gnd vin gnd 50k ? 100k ? 2k ? vin gnd en gnd gnd 130k ? 240k ? sw vin gnd vreg 5 boot sw ss / delay 50k ? 50k ? 2k ? vin vin sgnd sgnd sgnd pgnd fc 5k ? 400 ? 10k ? 10k ? rt gnd vin gnd 2k ? 10k ? 1k ?
technical note 12/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv note for use 1. about the absolute maximum rating attention is brushed off enough to the qua lity control, it is likely to destroy when the absolute maximum rating such as impressed voltages (vcc_in,dcin) and ranges (topr) of the operating temperature as it is exceeded, the mode of breakings of the short or the opening, etc. cannot be specified, and examine it in this ic to give physical measures for safety such as fuses when a special mode that exceeds the absolute maximum rating is assumed. 2. gnd pin voltage gnd terminal should be connected the lowest voltage, under al l conditions. and all terminals except sw should be under gnd terminal voltage under all conditions including transient situations. if a terminal ex ists under gnd,it should be inserting a bypass route. 3. power dissipation if ic is used on condition that the power loss is over the power dissipation, the reliability will become worse by heat up, suc h as reduced output current capability. also, be sure to use this ic within a power dissipation range allowing enough of margin. 4. input supply voltage input supply pattern layout should be as short as possible. 5. about the short and the miss-installation between terminals note the direction and the miss-registration of ic enough when you install it in the set substrat e. ic might destroy it as well as reversely connecting the power supply connector when installing it by mistake. moreover, there is fear of destruction when the foreign body enters between terminals, the terminal, t he power supply, and grandeur and it is short-circuited. 6. about operation in st rong electromagnetic field in use in strong electromagnetic field, note t hat there is a possibility of malfunctioning. 7. about the inspection by the set substrate it is likely to suffer stress to ic and discharge electricity ev ery one process when you connect the capacitor with the pin with low impedance when inspecting it in the set substrate. moreover, detach it after connecting after the power supply is turned off without fail when detaching it to g in the inspection process, inspecting, and turning off the power supply. in addition, be give the earth to the assembly process as a static electricity measures, and careful enough when it transports and you preserve it. 8. about each input terminal this ic is a monolithic ic which has a p + isolations and p substrate to isolate elements each other. this p layer and an n layer in each element form a pn junction to construct various parasitic elements. for instance, the potential difference operates in resistan ce as shown in the figure below when resistance and the transistor connect it with the terminal and the playground (gnd) >(terminal b) joint of pn operates as a parasitic diode in playground (gnd) >(terminal a) transistor (npn). in addition, the npn transistor of parasitism works with n layer of the element of the above-mentioned parasitic diode and the neighborhood and others in tr ansistor (npn). a parasitic element in ic composition is inevitably fo rmed because of the pot ential relation. a parasitic element can operate, the interf erence with the circuit operation be caused, it malfunction, and, consequently, it cause destruction. therefore, do not do the usage that a parasitic element operates as a voltage that is lower than the playground (gnd; p substrate) is impressed to the input terminal enough. moreover, do not impress the voltage to the input terminal when you do not impress the power-supply voltage to ic. give each input terminal to me the voltage below the power-supply voltage or in the guarantee value of an electric characteristic when you similarly impress the power-supply voltage. terminal a parasitic element gnd p + p p substrate termin al a parasitic element terminal b parasitic element gnd p p substrate cb gnd e terminal b e c b parasitic element gnd resistance transistor (npn) p + p + p + terminal of neighborhood and others example of ic of simple structure 9. earth wiring pattern if small signal gnd and large current gnd ex ist, disperse their pattern. in addition, for voltage change by pattern wiring impedance and large current not to change voltage of small signal gnd, each ground terminal of ic must be connected at the one point on the set circuit board. as for gnd of external parts, it is similar to the above-mentioned. 10. about each output terminal we recommend to put diode for protection purpose in case of output pin connected with large load of impedance or reserve current occurred at initial and output off. 11. thermal shut down circuit a temperature control is built in the ic to prevent the damage due to overhea t. therefore, the outputs are turned off when the thermal circuit works. 12. over output current protection sw output terminal has over current protection circuit of 5a, wi th prevents ic from being damage by short circuit at over current. however, it is recommend not to use that continuously operates the protection circuit (for instance, always the load that greatly exceeds the output current ability is connected or the output is s hort-circuited, etc.) in these protection circuits by an effective one to the destruction prevention due to broken accident.
technical note 13/13 www.rohm.com 2010.09 - rev. a ? 2010 rohm co., ltd. all rights reserved. bd8649efv ordering part number b d 8 6 4 9 e f v - e 2 part no. part no. package efv: htssop-b20 packaging and forming specification e2: embossed tape and reel (unit : mm) htssop-b20 s 0.08 s 11 20 110 (max 6.85 include burr) 6.5 0.1 (2.4) 4.4 0.1 0.325 6.4 0.2 (4.0) 0.17 +0.05 - 0.03 1.0 0.2 0.5 0.15 0.65 0.08 0.05 0.85 0.05 1.0max 0.24 +0.05 - 0.04 ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape (with dry pack) 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
r1010 a www.rohm.com ? 2010 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 specified herein is subject to change for improvement without notice. the content specified 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 specifications, 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 specified 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 specified 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 specified in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, office-automation equipment, commu- nication devices, electronic appliances and amusement devices). the products specified 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, fire or any other damage caused in the event of the failure of any product, such as derating, redunda ncy, fire 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, aerospac e 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 specified 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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