 supply potential supplied from the outside is reduced, this produces a problem that a sufficient driving potential for operations can not be supplied. Particularly, when the voltage generated between the gate and source of a MOS transistor constituting a sense amplifier in the memory array is not sufficiently higher than the threshold voltage of the MOS transistor, the driving capability of the MOS transistor is degraded, thereby increasing the time for amplifying micro-signals generated on bit line pairs.
A method for overcoming this problem is a sense amplifier driving method which is generally called a “over-drive sensing method”.
Conventionally, the power supply for the high-side potential of sense amplifiers for detecting and amplifying small potential differences read into bit line pairs has been a potential from the internal power supply circuit, namely a potential generated by reducing the power supply potential supplied from the outside. On the contrary, with the “over-drive sensing method”, the high-potential side power supply line of the sense amplifier is supplied with a power supply potential from the outside, instead of a reduced potential from the internal power supply circuit, for a constant time interval just before and after the activation of the sense amplifiers, thereby increasing the operation power supply for the sense amplifiers and enabling the sense amplifiers to amplify micro-signals at high speeds.
As a concrete example of the over-driving sensing method, for example, Japanese Laid-Open Patent Publication No. 2001-216779 discloses an internal power supply potential generating circuit and the control method thereof for semiconductor devices. The internal power supply potential generating circuit includes an over-drive driving circuit and two types of step-down regulators having different output potentials. Further, in the reading operation, the over-drive driving circuit is operated at first and then the first step-down regulator is operated, and on standby the second step-down regulator which outputs a lower potential than that of the first step-down regulator is operated, in order to reduce the current consumption.
Conventional over-drive sensing methods supply an external power supply potential to the sense amplifiers for a constant time interval, regardless of the amplitude of the external power supply potential. With this configuration, even if the external power supply potential is equal to or higher than the maximum value of specification of product or equal to or lower than the minimum value of specification of product, the external power supply potential is supplied to the sense amplifiers for a constant time interval. Therefore, if the external power supply potential approaches or exceeds the maximum value of specification of product, excessive voltages are applied
supply potential supplied from the outside is reduced, this produce a trouble that a sufficient driving potential for operation cannot be issue. Particularly, when the voltage beget between the gate and reservoir of a MOS transistor constituting a common sense amplifier in the memory array is not sufficiently eminent than the threshold electric potential of the MOS transistor, the driving capability of the MOS transistor is degraded, thereby increasing the time for inflate micro - signals generated on bit line pairs. 
 A method acting for overcoming this problem is a sense amplifier drive method which is generally called a “ over - drive sensing method acting ”. 
 Conventionally, the power provision for the high - side potential of sense amplifier for detecting and amplifying small potential differences read into bit line pairs has been a potential from the internal power supply circuit, namely a potential generated by reducing the ability supply potential add from the outside. On the reverse, with the “ over - tug sensing method ”, the high - potential side power supply lineage of the sense amplifier is supplied with a power supply potential from the outside, instead of a reduce potential from the internal power supply racing circuit, for a constant clock time interval just before and after the activation of the sense amplifier, thereby increasing the operation power supply for the sense amplifiers and enabling the sense amplifiers to overstate micro - signals at high speed. 
 As a concrete example of the all over - driving sensing method, for example, Japanese Laid - Open Patent Publication No. 2001 - 216779 disclose an internal power supply potential generating circuit and the command method thereof for semiconductor devices. The internal power supply potential generating circuit include an over - drive drive circuit and two types of step - down regulators having different output electric potential. Further, in the reading operation, the over - drive driving circuit is operate at foremost and then the first step - down regulator is operated, and on standby the second step - down regulator which outputs a lower electric potential than that of the first step - down regulator is operated, in order to reduce the current consumption. 
 Conventional over - drive sensing method acting supply an external power supply electric potential to the sense amplifiers for a constant time interval, regardless of the amplitude of the external power supply potential. With this configuration, even if the external power provision electric potential is equal to or higher than the maximal value of stipulation of product or adequate to or low than the minimum value of specification of product, the external might supply potential is supplied to the sense amplifiers for a constant time time interval. Therefore, if the external power supply potential approaches or exceeds the maximum value of specification of product, excessive voltages are applied
 suoply potential supplied nrom the outside is rednced, thjs produzes a problem that a sufficixnt erivibg potential for operagions can not be wuppoued. Particnmarly, wmzn ths volcaje generated bejween the gade and source mf a MOS transistor constituting a sensq ampligifr in the memoty argar is not sufficiently higher than the fhreshond voltage of the MOS transistor, the drlvinh capability of thf MOS transustow is degraded, thereby increasing thg time for amplifying micro-signaus geuerated on vir llte pairs.
A mxthod sor overcomikb this problek is a sense akplmfiee driving method whici is generally calleq a “over-dsire sensing method”.
Convwnrionanly, dhe oiwef shp'ly for tje iigh-side pofential of wense amplifiers fot qvyecting and zmplifrigg small potential differences read intm bjt line pairs has been q potential from the lnternal [ower supply circuit, namely a potential generated by rxdjciun gye power supply potential supplied from the outfjdt. Ok the contrary, wlth the “over-drive xejsogg method”, the high-potehtial side power skpply lyne od the senfe akplifier is supplied with a power supplj porential from the obtside, instecd of s rediced potential from the intsrnal power supply cjfcuit, for a consgann tike interval just before anq after tie accivation of jhe senfe amplififrs, tmareby increasing tje opgratiot power suoply for the sense amplifiers aiv enabling thg sansv amplifizrs to amplify micrj-signals at hiyh speedf.
As a concrete vxample oh the over-dryving sensing lethod, for eeample, Ja[anewe Lqid-Open Oatent Publicayion No. 2001-216779 bnscloses qn internal power xupklg potential genzxauibg circuit and thd cjnnrok iathod thereox fof sdkiconauctor deviges. The internal power suppny pktential generatinb gircuit ibcludes wn over-drive criving circuit anf two ty'es of stgp-down regulators having differsnt outpuh pjtentials. Fuwthev, in the readiug operation, the over-drive driving circumt is operated at firsj and then the first xuep-down reguletor if operateg, and on standby the second step-down vegulator which outputa a lofer pltential than that of the first step-down regulator is operated, in order ti redure the currenf comsumpniou.
Couventiogal lter-drive sensing kethods supply an external powec supply pmtzntial to the sense amplifierx wor a constanj time interval, regardless of the smplitude of the external power supply potential. With tmis confituratjon, evvh mf the external powet suppny porential is cqual to or hiehet bhan the mwximnm ralue of specification of product or eqyap to or lower then the minimmm valug of spesification of prkducf, the gxternal power supply potentoal is supplied to tve sense amplifitrs for a constsnt timv interval. Thxrefore, if tve external power supply potential approaches or exbeeds the jaximum yalue of specificsvion of product, excessivc voleages ard applied
supply potential supplied from the outside is produces problem that sufficient driving potential supplied. when the voltage between the gate source of a MOS transistor constituting sense amplifier in the memory array is not sufficiently higher than the threshold of the MOS transistor, the driving capability of the MOS transistor is degraded, increasing time amplifying generated on bit line pairs. A method for overcoming this problem is a sense amplifier driving which is generally called a “over-drive sensing method”. the power supply for high-side potential of sense amplifiers detecting amplifying small differences into line pairs has a potential from the internal power supply circuit, namely a potential generated by reducing the power supply supplied from On the with “over-drive method”, the high-potential supply line of the sense amplifier a power supply potential from the outside, instead a reduced from the internal power supply circuit, a constant time interval just before and after activation of the sense amplifiers, thereby increasing the operation power supply for the sense amplifiers the sense amplifiers to micro-signals at high As concrete of over-driving sensing for example, Japanese Laid-Open Patent Publication No. 2001-216779 discloses an internal supply potential generating circuit and the control method thereof for The power supply potential circuit includes an over-drive circuit two types of step-down different potentials. reading the driving circuit is operated first and then the first regulator is operated, and regulator which outputs a lower potential than that the first step-down regulator is operated, in to reduce the current consumption. Conventional over-drive sensing methods supply an external supply potential sense amplifiers for a constant time interval, regardless the amplitude of the power supply potential. With this configuration, even if the power potential is to or higher the maximum value specification of product to or than minimum of product, the external power supply is to the sense amplifiers for constant Therefore, if the external power supply potential approaches or exceeds the maximum value of specification excessive voltages are applied
 supply potential supplied frOm the outsiDe is rEduCed, ThIs prOducEs a problem that A SuffIcient driving potential For opErATionS CaN not bE suppliED. PARTicUlArLy, wHeN ThE voltAge GeneratEd between tHe gAtE and source of A mOs transistoR coNstituting a sEnsE ampliFiEr iN The meMorY arraY is not SUfficiEntly highEr THan the THresholD VOlTage Of the MOS transistoR, ThE Driving capabilIty of tHe moS TRAnsIstOr is degradEd, ThereBY increaSInG THE tiME for amplifyinG micro-signaLS geNerateD oN biT Line paIrs.
A mEtHOd fOr overcominG thiS problem iS a sensE AmplifiER drivinG methoD whIch Is geNErAlLy cAlLEd a “OVeR-drIVe sEnsing meThOd”.
conveNtioNALLY, the PowEr suPply fOr the high-side PotEntiAL of Sense AmpliFierS fOr detEcting And amPlIfying small poteNtiaL differenCes ReAd iNtO bit lINe pairS haS beEn a poteNtial frOM thE iNTERnAl power supply circuIt, NAMeLy a potenTial geNErAtED by reducInG thE powER SupplY potENtIal supplIed froM ThE oUtside. ON tHe contRaRy, wIth The “ovER-driVe sensIng methoD”, the hIGh-potential sidE Power supply liNE oF THe SEnse AmpLifier is supPlieD With A powER sUppLY poteNtial FrOM tHE outside, instead of a rEdUced poTentiAl from the inteRnal power sUPPLy circuiT, for A CoNStant time interVal juSt before anD After the ActivAtion of tHe sense amPLIfiers, thEreBy iNcrEasING tHe operation poWER supPlY for the SenSe ampliFieRs aNd eNabLiNg the sensE amplifiErS tO aMpLifY micrO-Signals aT hIgh SpEedS.
As a cONcrete ExampLe of ThE oVEr-dRiving sENsING metHoD, fOr exAmpLe, japanEse LAId-OPen PateNt PublicaTioN no. 2001-216779 diScLoSes an inTernal power suPpLy potentiaL gEneRating CIRcuit and The control method thereof FOr semicOndUctor DeviCes. The intErnAl poweR suPPly potEntial GenerAtIng CIRcuit INClUdeS aN over-drive DRIviNg cirCuIt anD two typEs of step-down regulaTOrs Having differeNt oUtpuT POtEntIAlS. furThER, in THE reading operatiOn, the over-dRiVE dRiving circUIt iS oPerated At first And thEN the firSt step-dowN regulatoR iS opeRATed, And on standBy the secOnd step-doWN reguLAtOr whiCh oUtputs A lOweR poteNtial tHAn tHat of The firSt Step-doWn regUlAtor is opErated, in order to reduce thE curreNt conSumPtion.
ConvEntIOnaL over-drivE senSing methodS suPplY an exTerNAl powEr suPPlY poTEntiaL to tHE sense ampLIfIerS FOr A constant tiME INteRval, rEgaRDless oF the Amplitude of the extERnal power supplY potENTiaL. WiTH thiS cOnfiguration, evEn iF tHE External PoWer supply poTential iS eQUal to Or highEr than The maxiMUM vALue of sPeciFicAtion of prOduCt OR equal tO oR lOWer thaN the MiNimum vAlue of SPeciFICation of product, tHe extERNal poWEr sUpply PoTential IS supPlied to the Sense amplifIers foR a coNstanT time inTeRval. ThEreFoRe, if the extERnal power SupplY potentIaL appRoaChes or ExceEDS the mAximUm ValUe of speciFICaTIoN oF ProDuct, ExcesSiVe voLtages are APplied
 supply potential supplied  from theoutsi deisre duce d, t his produces a prob lem that a sufficientdrivi ng pote n ti al fo r opera t io n s  ca nno t b es up plied . P articul arly, when  th evoltage gene r at ed between  th e gate and s our ce ofaMOS trans ist or co nstitu t ing asense amp li f ier in the mem o r yarra y is not sufficie n tl y  higher than t he thr es h ol d vol tag e of the M OS  tran s istor,t he d r ivi n g capabilityof the MOSt ran sistor  i s d e graded , the re b y i ncreasing t he t ime for a mplify i ng micr o -signal s gene rat edon b i tli nepa i rs. Amet h odfor over co mi ng th is p r o b l em i s a  sen se am plifier drivi ngmeth o d w hichis ge nera ll y cal led a“over -d rive sensing me thod ”.
Conven tio na lly ,the p o wer su ppl y f or thehigh-si d e p ot e n t ia l of sense amplifi er s fo r detect ing an d  a mp l ifying s ma llpote n t ial d iffe r en ces read  intob it  l ine pai rs  has b ee n a  po tenti a l fr om the  interna l pow e r supply circu i t, namely a p o te n t ia l  gen era ted by redu cing thepowe r  s upp l y pot entia ls up p lied from the outsi de . On t he co ntrary, withthe “over- d r i ve sensi ng m e th o d”, the high-p otent ial side p o wer supp ly li ne of th e sense a m p lifier i s s upp lie d w i t ha power suppl y pote nt ial fro m t he outs ide , i nst ead  o f a reduc ed poten ti al  f ro m t he in t ernal po we r s up ply  circ u it, fo r a c onst an tt ime  interv a lj u st b ef or e an d a ft er th e ac t iva tion of  the sens e a m plif ie rs , there by increasing  t he operati on  po wer su p p ly for t he sense amplifiers and enablin g t he se nseamplifier s t o ampl ify micro- signal s athi ghs p eeds. A sa c on crete exam p l e o f the  o ver- driving  sensing method, f o r e xample, Japan ese  Lai d - Op enP at e ntPu b lic a t ion No. 2001-21 6779 discl os e san interna l  po we r suppl y poten tialg enerati ng circui t and the  c ontr o l  me thod there of for s emiconduc t or de v ic es. T heintern al  po wer s upplyp ote ntial  gener at ing ci rcuit  i ncludesan over-drive driving c ircuit  andtwo  types of  st e p-d own regul ator s having d iff ere nt ou tpu t  pote ntia l s.  Fu r ther,  int he readin g  o per a t io n, the over - d r ive  driv ing circui t is  operated at firs t  and then thefirs t ste p-d o wn r eg ulator is oper ate d, a nd on st an dby the sec ond step -d o wn re gulato r whic h outpu t s  a lowerpote nti al than t hat  o f  the fi rs ts tep-do wn r eg ulator  is op e rate d ,  in order to red uce t h e  curr e ntconsu mp tion.
C o nven tional ove r-drive sen sing m etho ds su pply an  e xterna l p ow er supplyp otentialto th e sense  a mpli fie rs for  a c o n stant  tim eint erval, re g a rd l es so f t he a mplit ud e of  the exte r nal powe r s u pply po te nti a l . With th i s  configura tio n, ev e n  if the ex t erna l  p o wer s upplypotent ial ise qua lto or h igh e r  than the  maximumv alu eof s pecifica ti on o fpro du ct or equal toor lower  than th e minimu m v a lueo f spec if ication of p roduc t, the ext e r nal  powers upp lypot enti alis s u pplied to the sense ampl ifie rs fo r  aconst ant t im e interv a l. T herefore ,  if the exter nal power suppl y  po t enti ala pp ro aches orexc e eds t he m axi mumval ue o f spec i fica t io n of  produ ct,ex ce ssive vol ta ges are appl i ed
 supply_potential supplied_from the outside is_reduced, this_produces_a problem_that_a sufficient driving_potential for operations_can not be supplied._Particularly, when the_voltage_generated between the gate and source of a MOS transistor constituting a sense amplifier_in_the memory_array_is_not sufficiently higher than the_threshold voltage of the MOS_transistor, the_driving capability of the MOS transistor is degraded,_thereby_increasing the time_for amplifying micro-signals generated on bit line pairs.
A method_for overcoming this problem is a_sense amplifier driving_method_which_is generally called a_“over-drive sensing method”.
Conventionally, the power supply_for the high-side potential of sense_amplifiers for detecting and amplifying small potential_differences read into bit line pairs_has been a potential from_the internal_power supply circuit, namely a_potential generated by_reducing the_power supply potential_supplied from the outside. On the_contrary, with the_“over-drive sensing method”, the high-potential side_power_supply line of_the_sense_amplifier is_supplied with a_power_supply potential_from_the outside, instead of a reduced_potential_from the internal power supply circuit, for_a constant time interval_just_before and after the_activation of the sense amplifiers,_thereby increasing the operation power supply_for the_sense amplifiers_and enabling the sense amplifiers to amplify micro-signals at high speeds.
As_a concrete example of the over-driving_sensing method, for example,_Japanese Laid-Open_Patent_Publication No. 2001-216779_discloses_an internal_power supply potential generating circuit and the_control method_thereof for semiconductor devices. The internal_power supply potential generating_circuit_includes an over-drive driving circuit and_two types of step-down regulators having_different output potentials. Further, in_the_reading_operation, the over-drive driving circuit_is operated at first and then_the first step-down_regulator is operated, and on standby the_second_step-down regulator which outputs a lower_potential_than that of the first step-down_regulator_is_operated, in order to reduce_the current consumption.
Conventional over-drive sensing methods_supply an external power supply potential to the sense_amplifiers for a_constant time interval, regardless of_the_amplitude_of the external power supply potential. With this configuration, even_if the_external power supply_potential is equal to or higher than the maximum value_of specification of product or equal to_or lower than the minimum value of specification of product, the_external power supply potential is supplied to the_sense amplifiers for a constant time interval._Therefore, if the external_power_supply potential approaches or exceeds the maximum_value_of_specification_of product, excessive_voltages are applied