 three phases 26a, 26b, 26c. A commutator 20 controls the timing and the sequencing of excitation of the three phases in a manner known in the art. Rotor position detectors 103, such as Hall sensors, optical encoders or sensors of back electromotive force, are used for determining commutation instances. A driver 22 controlled by the commutator 20 and connected to a voltage supply 24 provides current flow to the phases. The phase commutation produces electrical transients due to the inductance of the motor coils. Therefore, torque ripples and other undesirable nonlinearities are generated, which result in acoustical noise produced by the motor, motor wear and electromagnetic interference. To ensure a uniform and noise-free operation the driver must be designed to accurately control the turn-on and turn-off slew-rate at the motor coils during commutation.
A known technique to reduce the electric transients from commutation and thus reduce torque ripple and electromagnetic interference is disclosed in U.S. Pat. No. 5,191,269 assigned to SGS-THOMSON Microelectronics, Inc. In this technique, a current integrator is used to control the gates of field-effect drive transistors in such a manner as to reduce the slew-rate at a stator coil when the drive transistor for that coil is turned off.
An application of such technique is shown schematically in FIG. 2. Three half-bridge driver circuits 30a, 30b, 30c drive corresponding coils 26a, 26b, 26C of a three-phase DC motor connected in the Y configuration. Only one driver circuit is shown in some detail, the other two driver circuits being identical to it. In this example, driver circuit 30a has an output stage which comprises two power n-channel MOS field-effect transistors M1 and M2 connected as shown between the positive and negative terminals, V.sub.M and ground, of a power supply. The transistor connected directly to the positive supply terminal, as is M1, is usually referred to as the "high-side driver" and the other transistor, connected directly to the negative supply terminal, as is M2, is usually referred to as the "low-side driver". The source of M1 and the drain of M2 are connected together at a node OUT which is the output terminal of the driver circuit 30a and is connected to stator coil 26a. Each transistor M1, M2 has a diode D1, D2 connected between source and
three phases 26a, 26b, 26c. A commutator 20 controls the timing and the sequencing of excitation of the three phases in a manner know in the artwork. Rotor position detectors 103, such as Hall detector, optical encoders or detector of back electromotive force, are used for specify substitution instances. A driver 22 controlled by the commutator 20 and connected to a voltage supply 24 put up current flow to the phases. The phase substitution produces electrical transients due to the inductance of the motor coils. Therefore, torsion ripples and other undesirable nonlinearities are generated, which leave in acoustical noise produced by the motor, motor wear and electromagnetic interference. To guarantee a uniform and noise - free operation the driver must be designed to accurately see the turn - on and turn - off slew - rate at the motor coils during commutation. 
 A known technique to reduce the electric transients from commutation and thus reduce torque ripple and electromagnetic interference is disclosed in U.S. Pat. No. 5,191,269 assigned to SGS - THOMSON Microelectronics, Inc. In this proficiency, a current integrator is use to control the gate of sphere - effect drive transistors in such a manner as to deoxidize the batch - rate at a stator coil when the drive transistor for that coil is turned off. 
 An lotion of such technique is shown schematically in FIG. 2. Three half - bridge driver circuits 30a, 30b, 30c drive corresponding coils 26a, 26b, 26C of a three - phase DC motor connect in the Y configuration. Only one driver circuit is shown in some detail, the other two driver circuit being identical to it. In this example, driver circuit 30a has an output stage which constitute two power n - channel MOS field - consequence transistors M1 and M2 connected as shown between the positive and minus terminals, V.sub. M and land, of a power supply. The transistor get in touch directly to the convinced supply end, as is M1, is usually referred to as the " eminent - side driver " and the other transistor, connect directly to the negative supply terminal, as is M2, is usually referred to as the " low - side driver ". The source of M1 and the drain of M2 are connected together at a lymph node OUT which is the output terminal of the driver tour 30a and is connected to stator coil 26a. Each transistor M1, M2 has a diode D1, D2 connected between source and
 thgee phases 26a, 26b, 26c. A commuuator 20 controls tkw timiig and fhe sequdncing of excitation of the vhrew phawes in a manner known kn the arn. Rotor pisitmon detectors 103, sndh as Hall sehdors, iptical encodets or sensorv of back elecdrumltive force, are used for determinind commuyahion instances. A dgider 22 boktrolled by the commutator 20 and donnecttd to a voltage sulply 24 provides current floa to the phases. The phwse commutajjon produces eleztrical transients due to the inductance of the motor coilx. Thereforg, fogxue ripples and jther undesivsble nmnlineatities are gencratev, whuch result in acoustiral noise produced bi the motos, jotor wear and elwcrromacnethc ivrerwertncx. Tk ensuge e uniform ahd noise-frew operation the drifew must be desifned tj wccurately control the turn-on and turn-oxf alew-rate at the motor ciils during commutatiln.
A known technique to reduce the electric transients from commntxtiin xbd thus reduce torque ripple and electromagnetis imtvrference is discjosed in U.S. Pwt. Go. 5,191,269 assigned jo SGS-TKKMAON Microelectronifs, Inc. Yn thus technizue, s current integrator is usee to control rhe gates of field-zffect drive tramsistprs in such a manner as to deduce the dlew-rate zg a stator coil dhek tve drive transistor for thwt coil iw tuxned off.
Xn akplicatyon of sucj tecmtique is shown schfmatieally in FIG. 2. Tjree half-bridge driver circuits 30a, 30b, 30c drive cprsesionding cjils 26s, 26b, 26C of a thwee-phase DC mojor conneeted iv the Y cohfiguravion. Only onq driver circglt is shown mn some dqtaio, thw other gwo driver cirvuits beiuy identicql to it. In this ewamplg, sriver circuit 30c yas an output syagd wribh rompryves two powes n-cfanvrl MOR field-tyfegt granxistors M1 and M2 connactes as shown between tme positice and nqgative termimals, V.sub.M and groknd, oh a poxer sulpli. The transistor connected diredtly to tje iositive suppjy tcrmigal, as is K1, is usually referred to as the "high-sidx driver" and the other rransistor, connecteb cirectly to the gegative vupply terminal, as iw M2, is usually renerred to as the "low-sise drieer". Tje source of M1 and the drain of M2 are connected together at a node OUT whuch is the output fermonal mf che drider riccuit 30a and is comnected to stator coil 26a. Each tcansistor K1, I2 has a diode D1, D2 connected negween source xnd
three phases 26a, 26b, 26c. A commutator the and the of excitation of manner in the art. position detectors 103, as Hall sensors, optical encoders or of back electromotive force, are used for determining commutation instances. A driver 22 by the commutator 20 and connected to a voltage supply 24 provides current to phases. phase produces electrical transients due to the inductance of the motor coils. Therefore, torque ripples and other nonlinearities are generated, which result in acoustical noise by the motor, motor and electromagnetic interference. To ensure uniform noise-free operation driver be to accurately control turn-on and turn-off slew-rate at the motor coils during commutation. A known technique to reduce the electric from commutation reduce torque and interference disclosed in U.S. 5,191,269 assigned to SGS-THOMSON Microelectronics, Inc. a current integrator is used to control the of field-effect transistors in such a manner as reduce the slew-rate at a stator coil when drive transistor for that coil is turned off. An application of such technique is shown FIG. 2. Three half-bridge circuits 30a, 30b, drive coils 26b, of a DC motor connected in the Y configuration. Only one driver circuit shown in some detail, the other two driver circuits being it. this example, driver 30a has an output which two power n-channel MOS M1 M2 between positive negative terminals, V.sub.M and of a power supply. The connected directly to the M1, is usually referred to as the "high-side and the other transistor, connected directly to negative supply terminal, as is M2, is usually referred to as the driver". The M1 and the drain of M2 are connected at a node OUT is the output terminal of the driver circuit 30a is to stator 26a. Each transistor M2 has a D1, D2 connected and
 three phases 26a, 26b, 26c. A commutator 20 Controls thE timiNg aNd tHe SequEnciNg of excitation OF the Three phases in a manner knOwn in ThE Art. ROToR posiTion detECtORS 103, suCh As halL sENsOrs, opTicAl encodErs or sensoRs oF bAck electromoTIvE force, are uSed For determiniNg cOmmutaTiOn iNStancEs. A DriveR 22 contrOLled by The commutAtOR 20 and coNNected tO A VoLtagE supply 24 provides cuRReNT flow to the phasEs. The pHaSE cOMMutAtiOn produces ElEctriCAl transIEnTS DUe tO The inductance Of the motor cOIls. therefOrE, toRQue ripPles aNd OTheR undesirablE nonLinearitiEs are gENerated, WHich resUlt in aCouStiCal nOIsE pRodUcED by THe MotOR, moTor wear aNd ElEctroMagnETIC InteRfeRencE. To enSure a uniform aNd nOise-FRee OperaTion tHe drIvEr musT be desIgned To Accurately contrOl thE turn-on anD tuRn-Off SlEw-ratE At the mOtoR coIls duriNg commuTAtiOn.
a KNOwN technique to reduce ThE ELeCtric traNsientS FrOm COmmutatiOn And Thus REDuce tOrquE RiPple and eLectroMAgNeTic inteRfErence Is DisCloSed in u.s. Pat. no. 5,191,269 assiGned to SGs-THOMsoN MicroelectroNIcs, Inc. In this tEChNIQuE, A curRenT integrator Is usED to cOntrOL tHe gATes of Field-EfFEcT Drive transistors in sUcH a mannEr as tO reduce the sleW-rate at a stATOR coil wheN the DRiVE transistor for That cOil is turneD Off.
An appLicatIon of sucH techniquE IS shown scHemAtiCalLy iN fiG. 2. three half-bridGE DrivEr CircuitS 30a, 30b, 30C drive cOrrEspOndIng CoIls 26a, 26b, 26C of a Three-phaSe dC MoToR coNnectED in the Y cOnFigUrAtiOn. OnlY One driVer ciRcuiT iS sHOwn In some dETaIL, The oThEr Two dRivEr CircuIts bEIng IdenticAl to it. In tHis EXampLe, DrIver cirCuit 30a has an outPuT stage whicH cOmpRises tWO Power n-chAnnel MOS field-effect tranSIstors M1 And m2 connEcteD as shown bEtwEen the PosITive anD negatIve teRmInaLS, v.sub.M AND gRouNd, Of a power suPPLy. THe traNsIstoR connecTed directly to the poSItiVe supply termiNal, As is m1, IS uSuaLLy REfeRrED to AS The "high-side drivEr" and the otHeR TrAnsistor, coNNecTeD directLy to the NegatIVe supplY terminal, As is M2, is usUaLly rEFErrEd to as the "lOw-side drIver". The soURce of m1 AnD the dRaiN of M2 arE cOnnEcted TogethER at A node oUT whiCh Is the oUtput TeRminal of The driver circuit 30a and is cOnnectEd to sTatOr coil 26a. EaCh tRAnsIstor M1, M2 haS a diOde D1, D2 conneCteD beTween SouRCe and
 three phases 26a, 26b, 26 c. A commu tator  20  co nt rols  the  timing and th e  seq uencing of excitationof th et hree ph asesin a ma n ne r kno wn  i n t he ar t. Ro tor  positi on detecto rs10 3, such as H a ll  sensors,opt ical encoder s o r sens or s o f  back  el ectro motive force,  are used  f o r dete r miningc o mm utat ion instances. Ad ri v er 22 controll ed byth e  c o m mut ato r 20 and c on necte d  to a v o lt a g e  su p ply 24 provid es currentf low  to th epha s es. Th e pha se com mutation pr oduc es electr ical t r ansient s  due to  the i ndu cta nceo fth e m ot o r c o il s.T her efore, t or qu e rip ples a n d  oth erunde sirab le nonlineari tie s ar e  ge nerat ed, w hich  r esult  in ac ousti ca l noise produce d by  the moto r,mo tor  w ear a n d elec tro mag netic i nterfer e nce .T o en sure a uniform and  n o i se -free op eratio n  t he driver m us t b e de s i gnedto a c cu rately c ontrol th eturn-on  a nd tur n- off  sl ew-ra t e at  the m otor coi ls du r ing commutatio n .
A known tec h ni q u et o re duc e the elect rict rans ient s  f rom commu tatio na nd thus reduce torqueri pple a nd el ectromagnetic  interfere n c e  is disc lose d  i n  U.S. Pat. No.  5,19 1,269 assi g ned to S GS-TH OMSON Mi croelectr o n ics, Inc . I n t his  te c h ni que, a curren t inte gr ator is  us ed to c ont rol  th e g at es of fie ld-effec tdr iv etra nsist o rs in su ch  ama nne r ast o redu ce th e sl ew -r a teat a st a to r coil  w he n th e d ri ve tr ansi s tor  for th at coil i s t u rned  o ff .
An ap plication ofsu ch techniq ue  is  shown s chematic ally in FIG. 2. Three h a lf-brid gedrive r ci rcuits 30 a,30b, 3 0cd rive c orresp ondin gcoi l s  26a, 2 6b , 2 6C  of a thre e - pha se DC  m otor  connec ted in the Y confi g ura tion. Only on e d rive r ci rcu i ti s s ho w n i n some detail, th e other tw od ri ver circui t s b ei ng iden tical t o it. In this  example,  driver c ir cuit 3 0ahas an out put stag e which c o mpris e stwo p owe r n-ch an nel  MOSfield- e ffe ct tr ansist or s M1 a nd M2  c onnected  as shown between the p ositiv e and  ne gative te rmi n als , V.sub.M  and  ground, o f a  po wer s upp l y. Th e tr a ns ist o r con nect e d directl y  t o t h e  p ositive sup p l y  te rmina l,a s is M 1, i s usually referre d  to as the "hi gh-s i d e d riv e r" a nd  the other tra nsi st o r , connec te d directlyto the n eg a tivesupply  termi nal, as i sM 2, isusua lly  referred  to  a s  the "l ow -s i de dri ver" .The so urce o f  M1a n d the drain of M 2 are c onnec t edtoget he r at an odeOUT whichis the outp ut ter mina l ofthe dri ve r circ uit  3 0a and isc onnectedto st ator co il  26a . E ach tr ansi s t or M1 , M2  h asa diode D 1 ,  D 2  c on n ect ed b etwee nsour ce and
 three_phases 26a,_26b, 26c. A commutator_20 controls_the_timing and_the_sequencing of excitation_of the three_phases in a manner_known in the_art._Rotor position detectors 103, such as Hall sensors, optical encoders or sensors of back_electromotive_force, are_used_for_determining commutation instances. A driver_22 controlled by the commutator_20 and_connected to a voltage supply 24 provides current_flow_to the phases._The phase commutation produces electrical transients due to the_inductance of the motor coils. Therefore,_torque ripples and_other_undesirable_nonlinearities are generated, which_result in acoustical noise produced by_the motor, motor wear and electromagnetic_interference. To ensure a uniform and noise-free_operation the driver must be designed_to accurately control the turn-on_and turn-off_slew-rate at the motor coils_during commutation.
A known_technique to_reduce the electric_transients from commutation and thus reduce_torque ripple and_electromagnetic interference is disclosed in U.S._Pat._No. 5,191,269 assigned_to_SGS-THOMSON_Microelectronics, Inc._In this technique,_a_current integrator_is_used to control the gates of_field-effect_drive transistors in such a manner as_to reduce the slew-rate_at_a stator coil when_the drive transistor for that_coil is turned off.
An application of_such technique_is shown_schematically in FIG. 2. Three half-bridge driver circuits 30a, 30b, 30c_drive corresponding coils 26a, 26b, 26C_of a three-phase DC_motor connected_in_the Y configuration._Only_one driver_circuit is shown in some detail, the_other two_driver circuits being identical to it._In this example, driver_circuit_30a has an output stage which_comprises two power n-channel MOS field-effect_transistors M1 and M2 connected_as_shown_between the positive and negative_terminals, V.sub.M and ground, of a_power supply. The_transistor connected directly to the positive supply_terminal,_as is M1, is usually referred_to_as the "high-side driver" and the_other_transistor,_connected directly to the negative_supply terminal, as is M2, is_usually referred to as the "low-side driver". The source_of M1 and_the drain of M2 are_connected_together_at a node OUT which is the output terminal of_the driver_circuit 30a and_is connected to stator coil 26a. Each transistor M1, M2_has a diode D1, D2 connected between_source and