Stepper Motor Controllers
The L297 Stepper Motor Controller IC generates four phase drive signals for two phase bipolar and four phase unipolar step motors in microcomputercontrolled applications. The motor can be driven in half step, normal and wawe drive modes and onchip PWM
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® L297
STEPPER MOTOR CONTROLLERS
NORMAL/WAVE DRIVE
HALF/FULL STEP MODES
CLOCKWISE/ANTICLOCKWISE DIRECTION
SWITCHMODE LOAD CURRENT REGULA-
TION
PROGRAMMABLE LOAD CURRENT DIP20 SO20
FEW EXTERNAL COMPONENTS
RESET INPUT & HOME OUTPUT ORDERING NUMBERS : L297/1 (DIP20)
L297D (SO20)
ENABLE INPUT
DESCRIPTION this device is that it requires only clock, direction
The L297 Stepper Motor Controller IC generates and mode input signals. Since the phase are gen-
four phase drive signals for two phase bipolar and erated internally the burden on the microprocessor,
four phase unipolar step motors in microcomputer- and the programmer, is greatly reduced. Mounted
controlled applications. The motor can be driven in in DIP20 and SO20 packages, the L297 can be
half step, normal and wawe drive modes and on- used with monolithic bridge drives such as the
chip PWM chopper circuits permit switch-mode L298N or L293E, or with discrete transistors and
control of the current in the windings. A feature of darlingtons.
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
Vs Supply voltage 10 V
Vi Input signals 7 V
Ptot Total power dissipation (Tamb = 70°C) 1 W
Tstg, Tj Storage and junction temperature -40 to + 150 °C
TWO PHASE BIPOLAR STEPPER MOTOR CONTROL CIRCUIT
December 2001 1/11
L297
PIN CONNECTION (Top view)
L297/1
L297D
BLOCK DIAGRAM (L297/1 - L297D)
2/11
L297
PIN FUNCTIONS - L297/1 - L297D
N° NAME FUNCTION
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.
2 GND Ground connection.
3 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.
4 A Motor phase A drive signal for power stage.
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.
6 B Motor phase B drive signal for power stage.
7 C Motor phase C drive signal for power stage.
8 INH2 Active low inhibit control for drive stages of C and D phases.
Same functions as INH1.
9 D Motor phase D drive signal for power stage.
10 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.
12 Vs 5V supply input.
13 SENS2 Input for load current sense voltage from power stages of phases
C and D.
14 SENS1 Input for load current sense voltage from power stages of phases
A and B.
15 Vref 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
16 OSC determines the chopper rate. This terminal is connected to ground
on all but one device in synchronized multi - L297 configurations. f
≅ 1/0.69 RC
17 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.
3/11
L297
PIN FUNCTIONS - L297/1 - L297D (continued)
N° NAME FUNCTION
19 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 SO20 Unit
Rth-j-amb Thermal resistance junction-ambient max 80 100 °C/W
CIRCUIT OPERATION are chopped the non-active phase line of each pair
(AB or CD) is activated (rather than interrupting the
The L297 is intended for use with a dual bridge line then active). In L297 + L298 configurations this
driver, quad darlington array or discrete power technique reduces dissipation in the load current
devices in step motor driving applications. It re- sense resistors.
ceives step clock, direction and mode signals from
the systems controller (usually a microcomputer
chip) and generates control signals for the power
stage. A common on-chip oscillator drives the dual chop-
The principal functions are a translator, which gen- per. It supplies pulses at the chopper rate which set
erates the motor phase sequences, and a dual the two flip-flops FF1 and FF2. When the current in
PWM chopper circuit which regulates the current in a winding reaches the programmed peak value the
the motor windings. The translator generates three voltage across the sense resistor (connected to
different sequences, selected by the HALF/FULL one of the sense inputs SENS1 or SENS2) equals
input. These are normal (two phases energised), Vref and the corresponding comparator resets its
wave drive (one phase energised) and half-step flip flop, interrupting the drive current until the next
(alternately one phase energised/two phases en- oscillator pulse arrives. The peak current for both
ergised). Two inhibit signals are also generated by windings is programmed by a voltage divider on the
the L297 in half step and wave drive modes. These Vref input.
signals, which connect directly to the L298’s enable Ground noise problems in multiple configurations
inputs, are intended to speed current decay when can be avoided by synchronising the chopper os-
a winding is de-energised. When the L297 is used cillators. This is done by connecting all the SYNC
to drive a unipolar motor the chopper acts on these pins together, mounting the oscillator RC network
lines. on one device only and grounding the OSC pin on
An input called CONTROL determines whether the all other devices.
chopper will act on the phase lines ABCD or the
inhibit lines INH1 and INH2. When the phase lines
4/11
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.
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 (1, 3, 5 or 7). In this mode the INH1 and INH2 outputs
remain high throughout.
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)
Symbol Parameter Test conditions Min. Typ Max. Unit
Vs Supply voltage (pin 12) 4.75 7 V
Is Quiescent supply current (pin 12) Outputs floating 50 80 mA
Vi Input voltage Low 0.6 V
(pin 11, 17, 18, 19, 20)
High 2 Vs V
Ii Input current Vi = L 100 µA
(pin 11, 17, 18, 19, 20)
Vi = H 10 µA
Ven Enable input voltage (pin 10) Low 1.3 V
High 2 Vs V
Ien Enable input current (pin 10) Ven = L 100 µA
Ven = H 10 µA
Vo Phase output voltage Io = 10mA VOL 0.4 V
(pins 4, 6, 7, 9)
Io = 5mA VOH 3.9 V
Vinh Inhibit output voltage (pins 5, 8) Io = 10mA Vinh L 0.4 V
Io = 5mA Vinh H 3.9 V
VSYNC Sync Output Voltage Io = 5mA VSYNC H 3.3 V
Io = 5mA VSYNC V 0.8
6/11
L297
ELECTRICAL CHARACTERISTICS (continued)
Symbol Parameter Test conditions Min. Typ Max. Unit
Ileak Leakage current (pin 3) VCE = 7 V 1 µA
Vsat Saturation voltage (pin 3) I = 5 mA 0.4 V
Voff Comparators offset voltage Vref = 1 V 5 mV
(pins 13, 14, 15)
Io Comparator bias current -100 10 µA
(pins 13, 14, 15)
Vref Input reference voltage (pin 15) 0 3 V
tCLK Clock time 0.5 µs
tS Set up time 1 µs
tH Hold time 4 µs
tR Reset time 1 µs
tRCLK Reset to clock delay 1 µs
Figure 1.
7/11
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.
Figure 3 : Synchronising L297s
8/11
L297
mm inch
DIM. OUTLINE AND
MIN. TYP. MAX. MIN. TYP. MAX. MECHANICAL DATA
a1 0.254 0.010
B 1.39 1.65 0.055 0.065
b 0.45 0.018
b1 0.25 0.010
D 25.4 1.000
E 8.5 0.335
e 2.54 0.100
e3 22.86 0.900
F 7.1 0.280
I 3.93 0.155
L 3.3 0.130
DIP20
Z 1.34 0.053
9/11
L297
mm inch
DIM. OUTLINE AND
MECHANICAL DATA
MIN. TYP. MAX. MIN. TYP. MAX.
A 2.35 2.65 0.093 0.104
A1 0.1 0.3 0.004 0.012
B 0.33 0.51 0.013 0.020
C 0.23 0.32 0.009 0.013
D 12.6 13 0.496 0.512
E 7.4 7.6 0.291 0.299
e 1.27 0.050
H 10 10.65 0.394 0.419
h 0.25 0.75 0.010 0.030
L 0.4 1.27 0.016 0.050
SO20
K 0˚ (min.)8˚ (max.)
L
h x 45˚
A
B e K A1 C
H
D
20 11
E
1 0
1
SO20MEC
10/11
L297
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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.
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