ME742EconomicalMicrosteppingDriverManualV1.0
Tel: +086 0755-264343697WebSite: www.leadshine.com
6. PowerSupply Selection
TheME742 canmatchmediumandsmall size steppingmotors(fromNEMAsize 16 to23)madeby
Leadshineorothermotormanufactures around theworld.Toachievegood drivingperformances, it is
importanttoselectsupplyvoltageandoutputcurrentproperly.Generallyspeaking,supplyvoltage
determines thehighspeedperformance ofthemotor,whileoutputcurrentdetermines theoutput
torqueofthedrivenmotor(particularlyatlowerspeed).Highersupplyvoltagewill allowhigher
motorspeedtobeachieved, attheprice ofmorenoise and heating.Ifthemotion speedrequirementis
low, it sbettertouse lowersupplyvoltagetodecrease noise, heatingand improvereliability.
Regulated orUnregulated PowerSupply
Bothregulatedandunregulatedpowersupplies canbeusedtosupplythedriver.However,
unregulatedpowersupplies arepreferredduetotheirabilitytowithstandcurrentsurge.Ifregulated
powersupplies (suchas mostswitchingsupplies.)areindeedused,it isimportanttohavelarge
currentoutputratingtoavoidproblemslikecurrentclamp,forexampleusing4Asupplyfor3A
motor-driveroperation. Ontheotherhand, ifunregulatedsupplyisused, onemayuse apowersupply
oflowercurrentratingthanthatofmotor(typically50%～70%ofmotorcurrent).Thereason isthat
thedriverdrawscurrentfromthepowersupplycapacitoroftheunregulatedsupplyonlyduringthe
ON durationofthePWMcycle,butnotduringtheOFF duration.Therefore,theaveragecurrent
withdrawnfrompowersupplyisconsiderablyless thanmotorcurrent.Forexample,two3Amotors
canbewell suppliedbyonepowersupplyof4Arating.
Multiple Drivers
It isrecommendedtohavemultipledriverstoshareonepowersupplytoreduce cost,ifthesupply
has enoughcapacity.Toavoidcross interference, DONOT daisy-chainthepowersupplyinputpins
ofthedrivers. (Instead,please connectthemtopowersupplyseparately.)
Attention: NEVERconnectpowerand groundinthewrongdirection,as it will damagetheME742.
Selecting SupplyVoltage
ThepowerMOSFETSinsidetheME742 canactuallyoperatewithin+20V－+70VDC,including
powerinputfluctuationandbackEMF voltagegeneratedbymotorcoilsduringmotorshaft
deceleration.Highersupplyvoltagecanincrease motortorqueathigherspeeds,thushelpfulfor
avoidinglosingsteps.However,highervoltagemaycause biggermotorvibrationatlowerspeed,and
it mayalsocause over-voltageprotectionorevendriverdamage.Therefore,it issuggestedtochoose
onlysufficientlyhighsupplyvoltageforintendedapplications,and it issuggestedtouse power
supplies withtheoreticaloutputvoltageof+24～+36V,leavingroomforpowerfluctuation and
back-EMF.
ME742EconomicalMicrosteppingDriverManualV1.0
Tel: +086 0755-264343698WebSite: www.leadshine.com
7. Selecting MicrostepResolutionand DriverOutputCurrent
Thisdriveruses an8-bitDIPswitchtosetmicrostepresolution,andmotoroperatingcurrent,as
shownbelow:
Microstep Resolution Selection
Microstepresolution issetbySW5, 6, 7, 8oftheDIPswitch as showninthefollowingtable:
Microstep
Steps/rev.(for1.8°motor) SW5 SW6 SW7 SW8
2 400 OFF ON ON ON
4 800 ON OFF ON ON
8 1600 OFF OFF ON ON
16 3200 ON ON OFF ON
32 6400 OFF ON OFF ON
64 12800 ON OFF OFF ON
128 25600 OFF OFF OFF ON
5 1000 ON ON ON OFF
10 2000 OFF ON ON OFF
20 4000 ON OFF ON OFF
25 5000 OFF OFF ON OFF
40 8000 ON ON OFF OFF
50 10000 OFF ON OFF OFF
100 20000 ON OFF OFF OFF
125 25000 OFF OFF OFF OFF
CurrentSettings
Foragivenmotor,higherdrivercurrentwill makethemotortooutputmoretorque,butatthesame
timecausesmoreheatinginthemotoranddriver.Therefore,outputcurrentisgenerallysettobesuch
thatthemotorwill notoverheatforlongtimeoperation.Since parallelandserialconnectionsof
motorcoilswill significantlychangeresultinginductance andresistance,itisthereforeimportantto
setdriveroutputcurrentdependingonmotorphase current,motorleadsandconnectionmethods.
Phase currentratingsuppliedbymotormanufacturerisimportantinselectingdrivercurrent, however
theselection alsodependson leadsand connections.
Thefirstthree bits(SW1,2,3)oftheDIPswitchareusedtosetthedynamiccurrent.Selectasetting
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