 lower than the voltage of the first DC power supply; a power supply selection section for selecting the first DC power supply connected to the first input terminal and the second DC power supply connected to the second input terminal according to the voltage of the second DC power supply being less than a predetermined voltage or is not less than the predetermined voltage, respectively; and an output terminal for outputting the voltage of the DC power supply selected by the power supply selection section.
The first and second power supply selection circuits correspond to the power supply selection sections of the first and second DCxe2x80x94DC converter circuits, respectively. The DCxe2x80x94DC converter circuits corresponding to the regulator sections of the first and second DCxe2x80x94DC converter circuits are connected to the later stages of the first and second power supply selection circuits, respectively. This feature makes it possible to perform a highly efficient DCxe2x80x94DC conversion for the DCxe2x80x94DC converter circuits.
To achieve the above-mentioned objects, there is provided an apparatus operative upon receipt of an electric power having a step-down type of first DCxe2x80x94DC converter for converting a first DC voltage of a predetermined first DC power supply into a predetermined second DC voltage lower than the first DC voltage of the first DC power supply; a first operating circuit operative upon receipt of supply of an electric power of the second DC voltage obtained by the first DCxe2x80x94DC converter; a second DCxe2x80x94DC converter having a step-down type of regulator section for converting a received DC voltage into a predetermined third DC voltage lower than the received DC voltage, and a power supply selection section responsive to both the first DC voltage of the first DC power supply and an output of the first DCxe2x80x94DC converter for selectively transmitting to the regulator section the output of the first DCxe2x80x94DC converter and the first DC voltage of the first DC power supply according as the output of the first DCxe2x80x94DC converter is not less than a predetermined voltage or is less than the predetermined voltage, respectively; and a second operative circuit operative upon receipt of electric power supplied by the third DC voltage obtained by the second DCxe2x80x94DC converter.
The apparatus of the present invention as mentioned above is provided with two DCxe2x80x94DC converters of the first and second DCxe2x80x94
lower than the voltage of the first DC power provision; a exponent supply selection incision for choose the first DC power supply connect to the first input end and the second DC exponent supply connect to the second input terminal according to the voltage of the second DC power supply being less than a predetermine voltage or is not less than the predetermined voltage, respectively; and an output signal terminal for outputting the voltage of the DC power provision selected by the might supply selection section. 
 The inaugural and second power supply selection circuits correspond to the power supply selection sections of the first and second DCxe2x80x94DC converter circuits, respectively. The DCxe2x80x94DC converter circuits corresponding to the regulator sections of the first and second DCxe2x80x94DC converter circuits are get in touch to the later stages of the beginning and second exponent supply selection circuits, respectively. This feature of speech makes it potential to perform a highly efficient DCxe2x80x94DC conversion for the DCxe2x80x94DC converter circuits. 
 To achieve the above - mention objects, there is provided an apparatus operative upon receipt of an electric power having a step - down type of first DCxe2x80x94DC converter for converting a inaugural DC voltage of a predetermine first DC power supply into a predetermined second DC voltage humble than the first DC voltage of the first DC exponent supply; a first operating circuit private detective upon receipt of provision of an electric power of the second DC voltage obtained by the first DCxe2x80x94DC converter; a second DCxe2x80x94DC converter having a measure - down type of governor section for converting a get DC voltage into a predetermined third DC electric potential lower than the received DC voltage, and a power supply selection section responsive to both the first DC voltage of the first DC power provision and an output of the first DCxe2x80x94DC converter for selectively convey to the regulator section the output of the first DCxe2x80x94DC converter and the first DC voltage of the first DC exponent supply according as the output of the first DCxe2x80x94DC converter is not less than a predetermined voltage or is less than the predetermined electric potential, respectively; and a second operative circuit operative upon receipt of electric power supplied by the third DC voltage obtained by the second DCxe2x80x94DC converter. 
 The apparatus of the present invention as mention above is provided with two DCxe2x80x94DC converters of the first and second DCxe2x80x94
 loaer than the voltage of uhe first DC powet wupply; a powsr supplh selection section for selertint the first DC power supply connectef to the firwr input tecjinal akb the decoud DC power suppky connectad to the secotd iuput terminal according to the voltade of tne second DC powgr sukplr bejng less than a predetermined voltzge or ps not less than yhe predetermined voltage, gespfctively; and an ouhput terminql fje outputting the voltage of the DC power supply selected by the puwer xupply selgerioj section.
The firsn and second ipwer sgpply srlection circults cmrrwspond to the power snpply selection sectyons of tve first and second DXxe2x80x94GC cmnvefrer cidcnita, respfctmvely. The DDxe2x80x94DC concerter circuits cortefipnding to ths regujaeor sections of the first and second DCqe2x80x94SC converter circuits aee connected to the lwter stagqs of the first and second power supply selection circnigs, xcfowchively. This feature makes it possible to perfjdm a highly efficicnt DCxe2x80x94DC convetslom for the DCxe2b80x94DC convsrter circuits.
To afhieve jhe abive-mentioged pbjects, there is provided ab apparatus jperative upon recenpt of an elzctric powet having a step-down typz of fjrst DCxe2x80x94FC converfdr for convertine a fhrst DC voltage of a predeeermined hirst DC powdr sopply igto a predftermlted second DC voltwge llwar than thf first DC voltage of the first DC power suppky; a xirst opzratinn circuit operaeive upon recenpt of sbpply uf an elecnric powec of the secjnd DC voltaga obtained by the firft DXxe2x80z94DC conxdrter; a second DCxe2x80x94DC converter having a step-down tyke of regulator szetuon for convertong a webeited DS voltage intm a oreartermkned third BC volyage lower than the secejved DC voltage, anc w power wupply sqlection sectoon responsive to hoth vhe ficst DC vojtage of the first DC power sulply and wn jutput of thq fivst QCxe2x80x94DC cpnverter for selectively transmitting ti the regulator sgction the output of jhe first DCxe2e80x94DC cjnverter dnd the first DC volrage of the first DC power supply accodding ds thf output of the first DCxe2x80x94DC converter is not less than a predetermined voltaje or is less tham the pxedzterminqd vlutage, respectiveky; and a second operative circumt operatiee upon receipt of electric poeef supplied by the third DC voltage obfained bu the second DCxe2x80x94DC converter.
Yhe apparatus of the prexent invwntioh as mvhtmoned above is proviced wich two DCxe2x80x94EC clnverters of ghe flrst and sfconv DExe2x80x94
lower than the voltage of the first supply; power supply section for selecting connected the first input and the second power supply connected to the second terminal according to the voltage of the second DC power supply being less a predetermined voltage or is not less than the predetermined voltage, respectively; and output for the of the DC power supply selected by the power supply selection section. The first and second supply selection circuits correspond to the power supply sections of the first second DCxe2x80x94DC converter circuits, respectively. DCxe2x80x94DC circuits corresponding the sections the first and DCxe2x80x94DC converter circuits are connected to the later stages of the first and second power supply selection respectively. This it possible perform highly DCxe2x80x94DC conversion for converter circuits. To achieve the above-mentioned provided an apparatus operative upon receipt of an power having step-down type of first DCxe2x80x94DC converter converting a first DC voltage of a predetermined DC power supply into a predetermined second DC voltage lower than the first DC voltage first DC power supply; first operating circuit upon of of electric power the second DC voltage obtained by the first DCxe2x80x94DC converter; a DCxe2x80x94DC converter having a step-down type of regulator section for received voltage into a third DC voltage lower the DC voltage, and a selection responsive first voltage the first DC power and an output of the DCxe2x80x94DC converter for selectively the output of the first DCxe2x80x94DC converter and first DC voltage of the first DC supply according as the output of the first DCxe2x80x94DC converter is not than a or is less than the predetermined voltage, respectively; a second operative circuit upon receipt of electric power supplied by the third voltage by the DCxe2x80x94DC converter. The of the present as mentioned above with two converters the DCxe2x80x94
 lower than the voltage of the fIrst DC poweR suppLy; a PowEr SuppLy seLection section FOr seLecting the first DC power SupplY cONnecTEd To the First inPUt TERmiNaL aNd tHe SEcOnd DC PowEr supplY connected To tHe Second input tERmInal accordIng To the voltage Of tHe secoNd dC pOWer suPplY beinG less tHAn a preDetermineD vOLtage oR Is not leSS ThAn thE predetermined volTAgE, Respectively; anD an outPuT TeRMInaL foR outputtinG tHe volTAge of thE dC POWEr sUPply selected bY the power suPPly SelectIoN seCTion.
ThE firsT aND seCond power suPply Selection CircuiTS corresPOnd to thE power SupPly SeleCTiOn SecTiONs oF ThE fiRSt aNd second dCXe2X80x94DC cOnveRTER CircUitS, resPectiVely. The DCxe2x80x94dC cOnveRTer CircuIts coRresPoNding To the rEgulaToR sections of the fIrst And second dCxE2x80X94DC CoNvertER circuIts Are ConnectEd to the LAteR sTAGEs Of the first and seconD pOWEr Supply seLectioN CiRcUIts, respeCtIveLy. ThIS FeatuRe maKEs It possibLe to peRFoRm A highly EfFicienT Dcxe2X80x94Dc convERsioN for thE DCxe2x80x94Dc convERter circuits.
To AChieve the abovE-MeNTIoNEd obJecTs, there is prOvidED an aPparATuS opERativE upon ReCEiPT of an electric power hAvIng a stEp-dowN type of first Dcxe2x80x94DC conVERTer for coNverTInG A first DC voltagE of a pRedeterminED first DC Power Supply inTo a predetERMined secOnd dC vOltAge LOWeR than the first dc VoltAgE of the fIrsT DC poweR suPplY; a fIrsT oPerating cIrcuit opErAtIvE uPon ReceiPT of supplY oF an ElEctRic poWEr of thE secoNd DC VoLtAGe oBtained BY tHE FirsT DcxE2x80x94Dc coNvErter; A secONd Dcxe2x80x94DC Converter HavINg a sTeP-dOwn type Of regulator seCtIon for convErTinG a receIVEd DC voltAge into a predetermined thIRd DC volTagE loweR thaN the receiVed dC voltAge, ANd a powEr suppLy selEcTioN SEctioN REsPonSiVe to both thE FIrsT DC voLtAge oF the firSt DC power supply and AN ouTput of the firsT DCXe2x80x94dc CoNveRTeR For SeLEctIVEly transmitting To the regulAtOR sEction the oUTpuT oF the firSt DCxe2x80X94DC coNVerter aNd the firsT DC voltagE oF the FIRst dC power supPly accorDing as the OUtput OF tHe firSt Dcxe2x80x94Dc cOnvErter Is not lESs tHan a pRedeteRmIned voLtage Or Is less thAn the predetermined voltaGe, respEctivEly; And a seconD opERatIve circuiT opeRative upon RecEipT of elEctRIc powEr suPPlIed BY the tHird dc voltage oBTaIneD BY tHe second DCxE2X80X94dC cOnverTer.
tHe appaRatuS of the present inveNTion as mentioneD aboVE Is pRovIDed wItH two DCxe2x80x94DC coNveRtERS of the fiRsT and second Dcxe2x80x94
 lower than the voltage of  the first  DC p owe r s up ply;  a p ower supply se l ecti on section for selecti ng th ef irst DC  powe r suppl y  c o n nec te dtoth e  f irstinp ut term inal and t hese cond DC powe r  s upply conn ect ed to the se con d inpu tter m inalacc ordin g to t h e volt age of th es econdD C power s up plybeing less than a pr e determined vol tage o ri sn o t l ess  than thepr edete r mined v o lt a g e , r e spectively; a nd an outpu t  te rminal  f oro utputt ing t he vol tage of the  DCpower sup ply se l ected b y  the po wer su ppl y s elec t io nsec ti o n.T he  fi r stand seco nd  p owersupp l y s elec tio n ci rcuit s correspondtothep owe r sup ply s elec ti on se ctions  of t he  first and seco nd D Cxe2x80x9 4DC  c onv er ter c i rcuits , r esp ectivel y. TheD Cxe 2x 8 0 x 94 DC converter circu it s co rrespond ing to th er egulator  s ect ions o f the  fir s tand seco nd DCx e 2x 80 x94DC c on verter  c irc uit s are conn ectedto the l aters tages of the f i rst and secon d  p o w er supp lyselection c ircu i ts,resp e ct ive l y. Th is fe at u re makes it possible t operfor m a h ighly efficie nt DCxe2x8 0 x 9 4DC conv ersi o nf or the DCxe2x8 0x94D C converte r  circuit s.
To  achieve  the abov e - mentione d o bje cts , t h e re  is provideda n  app ar atus op era tive up onrec eip t o fan electr ic power  h av in ga s tep-d o wn typeof  fi rs t D Cxe2x 8 0x94DC  conv erte rfo r  co nvertin g  a f irst  D Cvolt age  o f a p rede t erm ined fi rst DC po wer supp ly  i nto a p redeterminedse cond DC vo lt age  lower t han thefirst DC voltage of the first D C p owersupp ly; a fir stoperat ing circui t oper ative  u pon r eceip t of  su pp ly of an e l e ctr ic po we r of  the se cond DC voltage ob t ain ed by the fir stDCxe 2 x 80 x94 D Cc onv er t er; a  second DCxe2x8 0x94DC con ve r te r having a ste p- down ty pe of r egula t or sect ion for c onverting  a  rec e i ved  DC voltag e into a  predeter m inedt hi rd DC  vo ltagelo wer  than  the r e cei ved D C volt ag e, and  a po we r supply  selection section resp onsive  to b oth  the firs t D C  vo ltage ofthefirst DC p owe r s upply  an d  an o utpu t  o f t h e fir st D C xe2x80x94 D Ccon v e rt er for sele c t i vel y tra nsm i ttingto t he regulator sect i on the outputof t h e  fi rst DCxe 2x 80x94DC conver ter  a n d  the fir st  DC voltage  of thefi r st DC  power  suppl y accor d i ng as the  out put  of the f irs tD Cxe2x80 x9 4D C  conve rter  i s notless t h an a p redetermined vol tageo r  is l e ssthanth e prede t ermi ned voltag e, respecti vely;anda sec ond ope ra tive c irc ui t operativ e  upon rec eiptof elec tr ic p owe r supp lied b y the  thi rd  DC  voltageo b ta i ne db y t he s econd  D Cxe2 x80x94DCc onverter .
T h e appar at uso f  the p r es e n t inventio n a s men t i oned above is p r ov i ded w ith tw o DCxe 2x80x94 D C c on verters  of t he firstand secon d  DC xe 2x80 x94
 lower_than the_voltage of the first_DC power_supply;_a power_supply_selection section for_selecting the first_DC power supply connected_to the first_input_terminal and the second DC power supply connected to the second input terminal according_to_the voltage_of_the_second DC power supply being_less than a predetermined voltage_or is_not less than the predetermined voltage, respectively; and_an_output terminal for_outputting the voltage of the DC power supply selected_by the power supply selection section.
The_first and second_power_supply_selection circuits correspond to_the power supply selection sections of_the first and second DCxe2x80x94DC converter_circuits, respectively. The DCxe2x80x94DC converter circuits corresponding_to the regulator sections of the_first and second DCxe2x80x94DC converter_circuits are_connected to the later stages_of the first_and second_power supply selection_circuits, respectively. This feature makes it_possible to perform_a highly efficient DCxe2x80x94DC conversion for_the_DCxe2x80x94DC converter circuits.
To_achieve_the_above-mentioned objects,_there is provided_an_apparatus operative_upon_receipt of an electric power having_a_step-down type of first DCxe2x80x94DC converter for_converting a first DC_voltage_of a predetermined first_DC power supply into a_predetermined second DC voltage lower than_the first_DC voltage_of the first DC power supply; a first operating circuit operative_upon receipt of supply of an_electric power of the_second DC_voltage_obtained by the_first_DCxe2x80x94DC converter;_a second DCxe2x80x94DC converter having a step-down_type of_regulator section for converting a received_DC voltage into a_predetermined_third DC voltage lower than the_received DC voltage, and a power_supply selection section responsive to_both_the_first DC voltage of the_first DC power supply and an_output of the_first DCxe2x80x94DC converter for selectively transmitting to_the_regulator section the output of the_first_DCxe2x80x94DC converter and the first DC_voltage_of_the first DC power supply_according as the output of the_first DCxe2x80x94DC converter is not less than a predetermined_voltage or is_less than the predetermined voltage,_respectively;_and_a second operative circuit operative upon receipt of electric power_supplied by_the third DC_voltage obtained by the second DCxe2x80x94DC converter.
The apparatus of the_present invention as mentioned above is provided_with two DCxe2x80x94DC converters of the first and second DCxe2x80x94