Stepper motor controllers - STMicroelectronics

1 L297 Stepper motor CONTROLLERSNORMAL/WAVE DRIVEHALF/FULL STEP MODESCLOCKWISE/ANTICLOCKWISE DIRECTIONSWITCHMODE LOAD CURRENT REGULA-TIONPROGRAMMABLE LOAD CURRENTFEW EXTERNAL COMPONENTSRESET INPUT & HOME OUTPUTENABLE INPUTDESCRIPTIONThe L297 Stepper motor Controller IC generatesfour phase drive signals for two phase bipolar andfour phase unipolar step motors in microcomputer-controlled applications. The motor can be driven inhalf step, normal and wawe drive modes and on-chip PWM chopper circuits permit switch-modecontrol of the current in the windings. A feature ofDecember 2001 SymbolParameterValueUnitVsSupply voltage10 VViInput signals7 VPtotTotal power dissipation (Tamb = 70 C)1 WTstg, TjStorage and junction temperature-40 to + 150 CABSOLUTE MAXIMUM RATINGS this device is that it requires only clock, directionand mode input signals. Since the phase are gen-erated internally the burden on the microprocessor,and the programmer, is greatly reduced.

2 Mountedin DIP20 and SO20 packages, the L297 can beused with monolithic bridge drives such as theL298N or L293E, or with discrete transistors PHASE BIPOLAR Stepper motor CONTROL CIRCUIT DIP20 SO20 ORDERING NUMBERS : L297/1 (DIP20) L297D (SO20)1/11 PIN CONNECTION (Top view)BLOCK DIAGRAM (L297/1 - L297D)2/11L297/1L297DL297N NAMEFUNCTION1 SYNCO utput of the on-chip chopper SYNC connections The SYNC connections of all L297s to besynchronized are connected together and the oscillatorcomponents are omitted on all but one. If an external clock sourceis used it is injected at this collector output that indicates when the L297 is in its initialstate (ABCD = 0101).The transistor is open when this signal is phase A drive signal for power low inhibit control for driver stage of A and B a bipolar bridge is used this signal can be used to ensurefast decay of load current when a winding is de-energized.

3 Alsoused by chopper to regulate load current if CONTROL input is phase B drive signal for power phase C drive signal for power low inhibit control for drive stages of C and D functions as phase D drive signal for power enable input. When low (inactive) INH1, INH2, A, B, C and Dare brought input that defines action of low chopper acts on INH1 and INH2; when high chopperacts on phase lines supply for load current sense voltage from power stages of phasesC and for load current sense voltage from power stages of phasesA and voltage for chopper circuit. A voltage applied to this pindetermines the peak load RC network (R to VCC, C to ground) connected to this terminaldetermines the chopper rate. This terminal is connected to groundon all but one device in synchronized multi - L297 configurations. f 1 RC17CW/CCWC lockwise/counterclockwise direction control direction of motor rotation also depends on connectionof internally therefore direction can be changed at clock.

4 An active low pulse on this input advances the motorone increment. The step occurs on the rising edge of this FUNCTIONS - L297/1 - L297D3/11L297N NAMEFUNCTION19 HALF/FULLHalf/full step select input. When high selects half step operation,when low selects full step operation. One-phase-on full step modeis obtained by selecting FULL when the L297 s translator is at aneven- numbered full step mode is set by selecting FULL when thetranslator is at an odd numbered position. (The home position isdesignate state 1).20 RESETR eset input. An active low pulse on this input restores thetranslator to the home position (state 1, ABCD = 0101).PIN FUNCTIONS - L297/1 - L297D (continued)CIRCUIT OPERATIONThe L297 is intended for use with a dual bridgedriver, quad darlington array or discrete powerdevices in step motor driving applications. It re-ceives step clock, direction and mode signals fromthe systems controller (usually a microcomputerchip) and generates control signals for the principal functions are a translator, which gen-erates the motor phase sequences, and a dualPWM chopper circuit which regulates the current inthe motor windings.

5 The translator generates threedifferent sequences, selected by the HALF/FULL input. These are normal (two phases energised),wave drive (one phase energised) and half-step(alternately one phase energised/two phases en-ergised). Two inhibit signals are also generated bythe L297 in half step and wave drive modes. Thesesignals, which connect directly to the L298 s enableinputs, are intended to speed current decay whena winding is de-energised. When the L297 is usedto drive a unipolar motor the chopper acts on input called CONTROL determines whether thechopper will act on the phase lines ABCD or theinhibit lines INH1 and INH2. When the phase linesare chopped the non-active phase line of each pair(AB or CD) is activated (rather than interrupting theline then active). In L297 + L298 configurations thistechnique reduces dissipation in the load currentsense common on-chip oscillator drives the dual chop-per.

6 It supplies pulses at the chopper rate which setthe two flip-flops FF1 and FF2. When the current ina winding reaches the programmed peak value thevoltage across the sense resistor (connected toone of the sense inputs SENS1 or SENS2) equalsVref and the corresponding comparator resets itsflip flop, interrupting the drive current until the nextoscillator pulse arrives. The peak current for bothwindings is programmed by a voltage divider on theVref noise problems in multiple configurationscan be avoided by synchronising the chopper os-cillators. This is done by connecting all the SYNC pins together, mounting the oscillator RC networkon one device only and grounding the OSC pin onall other resistance junction-ambientmax80100 C/WTHERMAL DATA4/11L297 motor DRIVING PHASE SEQUENCESThe L297 s translator generates phase sequencesfor normal drive, wave drive and half step state sequences and output waveforms forthese three modes are shown below.

7 In all casesthe translator advances on the low to high transis-tion of rotation is indicate; for anticlockwise ro-tation the sequences are simply reversed RESET restores the translator to state 1, where ABCD = STEP MODEHalf step mode is selected by a high level on the HALF/FULL input. NORMAL DRIVE MODEN ormal drive mode (also called "two-phase-on" drive) is selected by a low level on the HALF/FULL inputwhen the translator is at an odd numbered state (1, 3, 5 or 7). In this mode the INH1 and INH2 outputsremain high throughout. 5/11L297 motor DRIVING PHASE SEQUENCES (continued)WAVE DRIVE MODEWave drive mode (also called "one-phase-on" drive) is selected by a low level on the HALF/FULL inputwhen the translator is at an even numbered state (2, 4, 6 or 8).SymbolParameterTest voltage (pin 12) 7 VIsQuiescent supply current (pin 12)Outputs floating 5080mAViInput voltage(pin 11, 17, 18, 19, 20) Low High2 VsVIiInput current(pin 11, 17, 18, 19, 20) Vi = L 100 A Vi = H 10 AVenEnable input voltage (pin 10) Low High2 VsVIenEnable input current (pin 10) Ven = L 100 A Ven = H 10 AVoPhase output voltage(pins 4, 6, 7, 9)Io = 10mAVOL Io = VVinhInhibit output voltage (pins 5, 8)

8 Io = 10mAVinh L Io = 5mAVinh VVSYNCSync Output VoltageIo = 5mAVSYNC V Io = 5mAVSYNC V ELECTRICAL CHARACTERISTICS (Refer to the block diagram Tamb = 25 C, Vs = 5V unless otherwisespecified)6/11L297 SymbolParameterTest current (pin 3)VCE = 7 V 1 AVsatSaturation voltage (pin 3)I = 5 mA offset voltage(pins 13, 14, 15)Vref = 1 V 5mVIoComparator bias current(pins 13, 14, 15) -100 10 AVrefInput reference voltage (pin 15) 0 3 VtCLKC lock time stSSet up time 1 stHHold time 4 stRReset time 1 stRCLKR eset to clock delay 1 sELECTRICAL CHARACTERISTICS (continued)Figure INFORMATIONTWO PHASE BIPOLAR Stepper motor CONTROL CIRCUITThis circuit drives bipolar Stepper motors with winding currents up to 2A. The diodes are fast 2A 3 : Synchronising L297s8 ANDMECHANICAL DATA9/11L2971101120 AeBDELKHA1 CSO20 MECh x 45 (min.)

9 8 (max.)OUTLINE ANDMECHANICAL DATA10/11L297 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences ofuse of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is grantedby implication or otherwise under any patent or patent rights of STMicroelectronics . Specification mentioned in this publication are subject tochange without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are notauthorized for use as critical components in life support devices or systems without express written approval of ST logo is a registered trademark of STMicroelectronics 2001 STMicroelectronics Printed in Italy All Rights ReservedSTMicroelectronics GROUP OF COMPANIESA ustralia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco -Singapore - Spain - Sweden - Switzerland - United Kingdom - United