ST L297 handbook
Contents
1. 1297 1 1297 CONTROL BLOCK DIAGRAM L297 1 L297D HALF FULL STEP a OUTPUT LOGIC RESET oO TRANSLATOR DIRECTION CwiCCw SENS Wet SENS 4 2 11 L297 PIN FUNCTIONS L297 1 L297D 1 SYNC Output of the on chip chopper oscillator The SYNC connections The SYNC connections of all L297s to be synchronized are connected together and the oscillator components are omitted on all but one If an external clock source is used it is injected at this terminal 09e mem HOME Open collector output that indicates when the L297 is in its initial state ABCD 0101 The transistor is open when this signal is active 5 INH1 Active low inhibit control for driver stage of A and B phases When a bipolar bridge is used this signal can be used to ensure fast decay of load current when a winding is de energized Also used by chopper to regulate load current if CONTROL input is low NN Motor phase C drive signal for power stage Active low inhibit control for drive stages of C and D phases Same functions as INH1 r m Motor phase D drive signal for power stage ENABLE Chip enable input When low inactive INH1 INH2 A B C and D are brought low 11 CONTROL Control input that defines action of chopper When low chopper acts on INH1 and INH2 when high chopper acts on phase lines ABCD 13 SENS Input for load current sense voltage from power stages of phases C and D Ed SENS Input for l2. Malta Morocco Singapore Spain Sweden Switzerland United Kingdom United States http www st com 1571 11 11
3. 1 3 5 or 7 In this mode the INH1 and INH2 outputs remain high throughout 0101 YJ PToe HOME ky 5 5642 5 11 L297 MOTOR DRIVING PHASE SEQUENCES continued WAVE DRIVE MODE Wave drive mode also called one phase on drive is selected by a low level on the HALF FULL input when the translator is at an even numbered state 2 4 6 or 8 ELECTRICAL CHARACTERISTICS Refer to the block diagram Tamb 25 C Vs 5V unless otherwise specified Quiescent supply current pin 12 Outputs floating Input voltage Low pin 11 17 18 19 20 High Input current pin 11 17 18 19 20 T 50 lt o o gt Enable input voltage pin 10 s IN k Enable input current 10 Phase output voltage lo 10mA VoL pins 4 6 7 9 5mA 3 9 Inhibit output voltage pins 5 8 lo 10mA Vinh L l 5mA Vinh H Sync Output Voltage lo 5mA e e T Io lo 5mA Vsync V L297 ELECTRICAL CHARACTERISTICS continued Reset to clock delay Figure 1 CWICCW HALF STEP FULL STEP RESET 4 711 L297 APPLICATION INFORMATION TWO PHASE BIPOLAR STEPPER MOTOR CONTROL CIRCUIT This circuit drives bipolar stepper motors with winding currents up to 2A The diodes are fast 2A types Figure 2 STEPPER MOTOR WINDINGS 5846 4 CONTROL
4. 205 n 01 008 2A FAST DIODES Figure 3 Synchronising L297s 584711 4 8 11 L297 OUTLINE AND MECHANICAL DATA L297 DIM inch MIN TYP MAX MIN TYP MAX A 2 35 2 65 0 093 0 104 Fo Pos fo Jom a fosfor rimari s eje 10 65 0 394 0 75 0 010 K 0 min 8 max OUTLINE AND MECHANICAL DATA 10 11 SO20MEC 4 L297 Information furnished is believed to be accurate and reliable However STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics Specification mentioned in this publication are subject to change without notice This publication supersedes and replaces all information previously supplied STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics The ST logo is a registered trademark of STMicroelectronics 2001 STMicroelectronics Printed in Italy All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia Brazil Canada China Finland France Germany Hong Kong India Israel Italy Japan Malaysia
5. 7 is intended for use with a dual bridge driver quad darlington array or discrete power devices in step motor driving applications It re ceives step clock direction and mode signals from the systems controller usually a microcomputer chip and generates control signals for the power stage The principal functions are a translator which gen erates the motor phase sequences and a dual PWM chopper circuit which regulates the current in the motor windings The translator generates three different 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 by the L297 in half step and wave drive modes These signals which connect directly to the L298 s enable inputs are intended to speed current decay when a winding is de energised When the L297 is used to drive a unipolar motor the chopper acts on these lines An input called CONTROL determines whether the chopper will act on the phase lines ABCD or the inhibit lines INH1 and INH2 When the phase lines 4 11 are chopped the non active phase line of each pair AB or CD is activated rather than interrupting the line then active In L297 L298 configurations this technique reduces dissipation in the load current sense resistors common on chip oscillator drives the dual chop per It supplies pulses at the
6. AY L297 STEPPER MOTOR CONTROLLERS NORMAL WAVE DRIVE HALF FULL STEP MODES CLOCKWISE ANTICLOCKWISE DIRECTION SWITCHMODE LOAD CURRENT REGULA TION PROGRAMMABLE LOAD CURRENT FEW EXTERNAL COMPONENTS RESET INPUT amp HOME OUTPUT ENABLE INPUT DESCRIPTION The L297 Stepper Motor Controller IC generates four phase drive signals for two phase bipolar and four phase unipolar step motors in microcomputer controlled applications The motor can be driven in half step normal and wawe drive modes and on chip PWM chopper circuits permit switch mode control of the current in the windings A feature of ABSOLUTE MAXIMUM RATINGS Supply voltage Vi Input signals Total power dissipation Tamb 70 C Storage and junction temperature Parameter DIP20 5020 ORDERING NUMBERS 1297 1 DIP20 12970 8020 this device is that it requires only clock direction and mode input signals Since the phase are gen erated internally the burden on the microprocessor and the programmer is greatly reduced Mounted in DIP20 and SO20 packages the L297 can be used with monolithic bridge drives such as the L298N or L293E or with discrete transistors and darlingtons 1 40 to 150 TWO PHASE BIPOLAR STEPPER MOTOR CONTROL CIRCUIT ENABLE 05 0 01 4008 2A FAST DIODES STEPPER MOTOR WINDINGS 1 11 December 2001 L297 PIN CONNECTION Top view CLOCK
7. chopper rate which set the two flip flops FF1 and FF2 When the current in a winding reaches the programmed peak value the voltage across the sense resistor connected to one of the sense inputs SENS or SENS equals Vref and the corresponding comparator resets its flip flop interrupting the drive current until the next oscillator pulse arrives The peak current for both windings is programmed by a voltage divider on the Vref input Ground noise problems in multiple configurations can be avoided by synchronising the chopper os cillators This is done by connecting all the SYNC pins together mounting the oscillator RC network on one device only and grounding the OSC pin on all other devices 4 L297 MOTOR DRIVING PHASE SEQUENCES The L297 s translator generates phase sequences Clockwise rotation is indicate for anticlockwise ro for normal drive wave drive and half step modes tation the sequences are simply reversed RESET The state sequences and output waveforms for restores the translator to state 1 where ABCD these three modes are shown below In all cases 0101 the translator advances on the low to high transis tion of CLOCK HALF STEP MODE Half step mode is selected by a high level on the HALF FULL input HOME 0100 594 NORMAL DRIVE MODE Normal drive mode also called two phase on drive is selected by a low level on the HALF FULL input when the translator is at an odd numbered state
8. oad current sense voltage from power stages of phases A and Vret Reference voltage for chopper circuit A voltage applied to this pin determines the peak load current An RC network R to Vcc C to ground connected to this terminal determines the MAC rate This terminal is connected to ground on all but one device in synchronized multi L297 configurations f 1 0 69 RC CW CCW Clockwise counterclockwise direction control input Physical direction of motor rotation also depends on connection of windings Synchronized internally therefore direction can be changed at any time 18 CLOCK Step clock An active low pulse on this input advances the motor one increment The step occurs on the rising edge of this signal 4 3 11 L297 PIN FUNCTIONS L297 1 L297D continued HALF FULL Half full step select input When high selects half step operation when low selects full step operation One phase on full step mode is obtained by selecting FULL when the L297 s translator is at an even numbered state Two phase on full step mode is set by selecting FULL when the translator is at an odd numbered position The home position is designate state 1 20 RESET Reset input An active low pulse on this input restores the translator to the home position state 1 ABCD 0101 THERMAL DATA Symbol Parameter DIP20 5020 Unit Thermal resistance junction ambient max 80 100 C W CIRCUIT OPERATION The L29
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ST L297 handbook