ORDERINGNUMBERS:L297 (OIP20) L2970 (5020)
• NORMALIWAWEDRIVE
• HALF/FULLSTEP MODES
• CLOCKWISEJANTICLOCKWISEDIRECTION
• SWITC HMODE LOAD CURRENT REGUL A-TION
• PROG RAMMABLE LOA DCURRENT
• FEWEXTERNALCOMPONE NTS
• RESETINPUT&HOMEOUT PUT
• ENABL E INPUT
OlP20
• ~ --
-5020
DESCRIPTION
Thel297/A/O StepperMotor ControllerIegene r-atesfourphase drivesignals for
two
phase bipolar and fourphaseunipo lar step motorsin microcom-puter-conlrolledapplications.The motor canbe driveninhalfstep,normaland wawe drive modes andon-ch ip PWMchoppercircuitspermit switch-mode controlof thecurrent in the windings. AABSOLUT EMAXIMUM RATINGS
feature of this device isthatitrequiresonly clock, direction and mode input signals.Since the phase are generatedinternallythe burden on the micro-processor.and the programmer,isgreatlyreduced.
Mounte d in DIP20 and8020packages,thel297 can be used withmonolithicbridgedrivessuch as theL298N or L293E,orwith discretetransistors and darlingtons.
Symbol Paramet er Value Unit
V. Supplyvoltage 10 V
V; Input signals 7 V
P~ Total powerdissipation(T"mt> - 70"C)
,
WTItg.Ti Storage andjunct ion temp erature -40 to+ 150 "C
TWOPHASE BIPOLA RSTEPPERMOTORCONTROL CIRCUIT
••
-Chapter 2 / Ele ctroni cs
L297-1.297D
PINCONNECTION (Top view)
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CNC Roboti cs
L297·l297 D
PINFUNCTIONS-l2971L297D
N' NAME FUNCTION
1 SYNC OUtputoftheon-chipchopper oscillator.
TheSYNCconnec tionsThe SYNC co-oecncos01alll297sto be sy nchrooi z ed arecoonecled togethe rand the oscillator components areomitted onallbutone.Ifan externalcloc k source is useditis inje ctedat thiste rmina l.
2 OND Groundconnec tion.
3 HOME Opencollec toroutpu tthat indicateswhenthe l297 is initsinitial slate(ABeD=0101).
Thetransistor isopen when thissigna l is active.
4 A Motor pha seAdrivesignalforpower stage.
5 INHl Activelow inhibitcontrolfordriver stageof A and B phases.
Whe na bipolarbridge is usedthis signalcan beused10 ensure fas!decay ofloadcu rrent when awindi ng isde-energi zed .Also usedbychopper10regulateloa d currentifCONT ROLinput is low.
6 B Motor phase8 driv e signa l for power stage.
7
e
Motor phaseCdriv e signa l for powerstage.S INH2 Activ elowinhibitcontrolfor drive stagesofC and 0 phases.
same function sasINH 1.
9 D Motor pha se0drive signal for power stage.
I .
ENABLE Chip enaare broughtble input.low. Whenlow(inactive)INH1.INH2,A.B, C andD11 CONT ROL Controlinp utthat delines actionofchopper.
When low chopperactsonINHl andIN H2;whenhighchopper actson phaselines ABC D.
12 V. 5V supplyinp ut.
13 SENS2 Input lorloa d cu rrentsensevo ltagefrompowerstages01pha ses CandD.
14 SENS, Input lorloa d curre ntsensevoltage from powerstages01phases AandB.
15 V., Referenc evoltagelor choppercircui t. Avolage applied tothis pin determinesthepeak load current.
AnRC network(Ato Vee.C to ground) comected to this terminal
, . ose
determinesthe chopper rate.This terminalis connecled10groundon allbutonedevice in synchronizedmulti -l297 config urations.I
==1I0.69RC
17 CWIC CW Clockwiseicountef'Clod(wisedirectioncontrolinpul.
Phy sical direction01motorrotation alsodepends onconnec tion ofwindings.
Sy nchronizedinte ma lly therefore directioncan becha nged at any time.
18 CLOC K Stepcloc k.Anactive low pulseon thisinput advancesIhe moto r oneinc reme nt.The step occurson the ris ing edge01thissignal.
--- liii SGS.~ ...::c.:.3/11
24
I
Chapter 2 I El ectron ics
1297· 12970
PINFUNCTIO NS . l2971L297 D(conlinued)
N' NAME FUNCTION
,.
HAl F/FUU Halflfu ll step select input.Whenhigh selectshalfstep operation, whenlowselects lun stepoperation.One-phas e-on fullstep mode isobtainedby selectingFULLwh8f1thel297'stranslatoris at an eveo-numoeredslate.Two-phase-onlullstepmode is set by selecting FULLwhe n the translatoris atanoddnumb eredposition.(The home positionis designate state 1).
20 RESET ResetinputAn activelowpulse on this inp ut restoresthe
translator to thehome position(state1,ABeD=010 1).
THERMAL DATA
TheLZ97isintendedfor use with a dualbridge driver, quad darlington arrayor discretepower devicesinstep motordrivingapplications. It re-ceivesstepclock,directionand modesignalsfrom the systemscontrolle r(usuallya microcomputer chip)andgenerates control signals forthepower stage.
The principalfunctionsareatranslator,which gen-erates the moto rphase sequenc es,anda dual PWMchoppe rcircuit which regulates thecurrentin themotor windings.Thetranslatorgenerates t hree differentseq uences,selectedby theHALF/FULL input.These arenormal(two phasesenergised ), wave drive(one phase energised) and half-step (alternatelyonephase energised/twophases en-ergised).Twoinh ibit sig nalsarealsogeneratedby the l297 inhalfstep and wave drive modes.These signals, whichconnect direct lytotheL29 8's enabl e input s,areintended to speed currentdeca y when a windingisde-energised.WhentheL297isused to drive aunipolar motor the chopper acts on these lines.
An inputcalledCONTROLdeterm ineswhethe r the chopperwill acton thephaselines ABCDor the inhibit lines INH1 andINH2.When the phase lines
4111
are choppedthenon-activephase line of eachpa ir (ABorCD) is activated(ratherthaninte rrupting the line thenactive).InL297+L298 configurationsthis technique reducesdissipationin the loadcurrent senseresistors.
Acommonon-chiposcillatordrivesthe dual chop-per.ltsupp liespulses at the choppe r rate whichset thetwo flip-flo psFF1and FF2. Whenthecurrentin awindingreach estheprogrammedpeakvalue the volta ge across the sense resistor (co nnected to one ofthese nseinputs SENSl orSEN&?) equals Vral and the correspo ndi ngcomparato rres ets its flipflop,inter rupting thedrive current until thenext oscillatorpulse arrives.The pea kcurrentforboth windingsisprogrammedby a voltaged ivideronthe V,alinp ut.
Groundnoise problemsin multip le configuratio ns canbeavoidedbysynchronising the chopper os-cillators. Thisis doneby connect ing allthe SYNC pinstogether.mounting the oscillatorRC network on one deviceonlyand groundingtheOSCpin on all other devices .
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CNC Robotics
L297·l297D
MOTORDRIVINGPHASESEQUENCES The L29Ts translator generatesphase sequences for normaldrive,wave driveand half stepmodes.
The statesequences and output waveforms for these three modes are shown below. In all cases the translatoradvances on the lowto high transis-tionof~.
Clockwise rotationis indicate;for anticlockwisero-tation the sequences are simply reversed
liESET
restores the translator to state 1,whereABeD = 0101.
HALFSTEP MODE
Half stepmodeis selected by a highlevelon the HALFiFOITinput.
o
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-NORMAL DRIVE MODE
Normaldrivemode (also called"two-phase -on"drive)is selectedbya low level on the HALFJro[[ input when the translator is at an odd numberedstate(1,3, 5 or 7). In thismode the