1/4 rev. b structure silicon monolithic integrated circuit product name synchronous rectification with bui lt-in fet type dc/dc converter ic model name b d 8 6 4 5 e f v features ? synchronous rectification with built-in fet type dc/dc converter ? reference voltage accuracy fb 0.8v1% ? switching frequency 250khz 2.3mhz synchronizable with external clock. ? over current protection circuit ? thermal shutdown ? output voltage watch vdet function ? input low voltage detection uvlo function ? soft start / start delay circuit absolute maximum rating ta=25 parameter symbol limits unit input supply voltage v in 7 v input terminal voltage v in p *1 v in v output terminal voltage v out * v in v output current i out 5 a power dissipation pd 3.2 * operating temperature topr -40 85 storage temperature tstg -55 150 1 v inp application terminal synclk, en, ss/delay, fb 2 v out application terminal sw, vdet, fc, rt 3 (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 min typ max unit input supply voltage v in 4 - 5.5 output current i out - - 4 a this product is not designed for pr otection against radioactive rays. status of this document the japanese version of this document is the formal specification. a customer may use this translation version only fo r a reference to help reading the formal version. if there are any differences in translation version of this document, formal version takes priority. be careful to handle because the content of the description of this material might correspond to the labor (technology in the design, manufacturing, and use) in foreign country exchange and foreign trade control law.
2/4 rev. b electrical characteristic (unless otherwise noted ta=25 , v in =5.0v) parameter symbol specification value unit condition min typ max vin supply current (operating) i q _ active - 500 700 a v fb = 0.83v, v fc = 1v vin supply current (standby) i q _ stb y - 0 10 a v en = 0v reference voltage (vref) v ref 0.792 0.8 0.808 v output rise detection voltage v ov p 30 60 90 mv monitoring fb terminal output decrease detection voltage v lv p -90 -60 -30 mv monitoring fb terminal terminal vdet output current i vdet 0.4 - - ma v vdet < 0.3v oscillation frequency f os c 2.0 2.3 2.6 mhz r rt = 43k ? pch fet on resistance r pfet - 70 105 m ? i sw = 1a nch fet on resistance r nfet - 50 85 m ? i sw = -1a uvlo voltage v uvl o 2.35 2.50 2.65 v sw leak current i lsw - 0 10 a v en = 0v, v in = 5.5v en terminal h threshold voltage v enh 1.1 - - v en terminal l threshold voltage v enl - - 0.4 v fc sink current i fcsi 5 10 - a fc source current i fcs o - -10 -5 a ss/delay terminal source current i sss o 2 4 6 a v fb :fb terminal voltage v en :en terminal voltage v fc :fc terminal voltage v vdet : vdet < 0.3v current capability should not exceed pd.
3/4 rev. b block diagram pin assignment no. symbol description no. symbol description 1 sgnd si g nal gnd terminal 11 pvin power su pp l y in p ut terminal 2 r t fre q uenc y ad j ustment resistance connection terminal 12 pvin power su pp l y in p ut terminal 3 vde t out p ut abnormalit y detection terminal 13 pvin power su pp l y in p ut terminal 4 sw switchin g out p ut terminal 14 svin si g nal s y stem p ower su pp l y in p ut terminal 5 sw switchin g out p ut terminal 15 synclk in p ut terminal for external clock s y nchronization 6 pgnd power gnd terminal 16 en enable in p ut terminal 7 pgnd power gnd terminal 17 nc - 8 pgnd power gnd terminal 18 ss/dela y soft start ad j ustment ca p acit y connection terminal 9 sw switchin g out p ut terminal 19 fc phase amends terminal 10 sw switchin g out p ut terminal 20 fb feedback terminal package outline htssop-b20 (unitmm) bd8645 lot no. 1pin mark product number
4/4 rev. b note on use 1 about the absolute maximum rating attention is brushed off enough to the quality control, it is likely to destroy when the absolute maximum rating such as impres sed voltages (vcc_in,dcin) and ranges (topr) of the operating temperature as it is exceeded, the mode of breakings of the short or the openi ng, etc. cannot be specified, and examine it in this ic to give physical measur es for safety such as fuses when a special mode that exceeds the absolute maximum rating is assumed. 2 about the reverse-connection of the power supply connector ic might destroy it by reversely connecting the power supply c onnector. give measures such as putting the diode between power s upply terminals of power supply and ic outside for the reverse-touching destruction protection. 3 power supply line please do measures such as putting the bypass capacitor in power supply-gnd nearest pin of this ic as the route of the resurrec tion current to cause the return of the current in which it resurrected it by the counter electromotive force of the coil. please confirm the characteristic of the electrolytic capacitor enough as the capacity omission etc. at the low temperature nev er happen, and decide it. 4 about grand potential any state of operation must become the lowest potential about the potential of the terminal gnd. moreover, confirm whether ther e is terminal that is actually the voltage of gnd or less including transients. 5 about the heat design think about permissible loss (pd) in an actual state of use, and do the heat design with the margin enough. 6 about the short and the miss-installation between terminals note the direction and the miss-registration of ic enough when you in stall it in the set substrate. ic might destroy it as well as reversely connecting the power supply connector when installing it by mistake. mor eover, there is fear of destruction when the foreign body enters b etween terminals, the terminal, the power supply, and grandeur and it is short-circuited. 7 about operation in strong electromagnetic field in use in strong electromagnetic field, note that there is a possibility of malfunctioning. 8 about the capacitor during output-gnd the current charged the capacitor with when vcc is 0v or is g nd and is short-circuited when a bi g capacitor is connected betwee n gnd output by some factors flows into the output and it is likely to destroy it. give the capacitor between gnd output to 0.1 f or less. 9 about the inspection by the set substrate it is likely to suffer stress to ic and discharge electricity every one process when you connect the capacitor with the pin wit h low impedance when inspecting it in the set substrate. moreover, detach it after c onnecting after the power supply is turned off without fail when detaching it to g in the inspection process, inspec ting, and turning off the power supply. n addition, be give the earth to the as sembly process as a st atic electricity measures, and careful enough when it transports and you preserve it. 10 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 resistance as shown in the figure below when resistance and the transistor c onnect it with the terminal and the playground (gnd) >(terminal b) joint of pn operat es as a parasitic diode in pl ayground (gnd) >(terminal a) tra nsistor (npn). in addition, the npn transistor of parasitism wo rks with n layer of the element of the above-mentioned parasitic diode and the nei ghborhood and others in transistor (npn). a parasitic el ement in ic composition is inevitably formed because of the potential relation. a parasitic element can operate, the interference with the circui t operation be caused, it malfunction, and, consequently, it c ause destruction. therefore, do not do the usage that a parasitic element opera tes as a voltage that is lower than the playground (gnd;p substrat e) 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-suppl y voltage or in the guarantee value of an electric characterist ic when you similarly impress the power-supply voltage. example of ic of simple structure 11 earth wiring pattern if small signal gnd and large current gnd exist, disperse their pa ttern. in addition, for voltage change by pattern wiring impe dance and large current not to change voltage of small signal gnd, each ground te rminal of ic must be connected at the one point on the set cir cuit board. as for gnd of external parts, it is similar to the above-mentioned. 12 thermal shut-down when a thermal shutdown operates, the dc/dc converter controller of all ch is turned off. when a thermal shutdown is released, the dc/dc converter controller of all ch becomes an operation beginning from turning off.
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