®
STEPPER MOT OR CONTROLLERS
NORMAL/WAVE DRIVE
HALF/FULL STEP MODES
CLOCKWISE/ANTICLOCKWISE DIRECTION
SWITCHMODE LOAD CURRENT REGULA-
TION
PROGRAMMA BLE LO A D CURRE NT
FEW EXTERNAL COMPONENTS
RESET INPUT & HOME OUTPUT
ENABLE INPUT
DIP20 SO20
ORDERING NUMBERS
L297D (SO20)
: L297/1 (DIP20)
L297
DESCRIPTION
The L297 Stepper Motor Controller I C generates
four phase drive signals for two phase bipolar and
four phase unipolar step motors in m icrocomputercontrolled applications. The motor can be driven in
half step, normal and wawe drive modes and onchip PWM chopper circuits permit switch-mode
control of the current in the windings. A feature of
this device is that it requires only clock, direction
and mode input signals. Since the phase are generated 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.
ABSOL UT E MAXIMUM R ATINGS
Symbol Parameter Value Unit
V
P
T
stg
Supply voltage 10 V
s
Input signals 7V
V
i
Total power dissipation (T
tot
, TjStorage and junction temperature -40 to + 150
amb
= 70°C)
1W
TWO PHASE BIPOLAR STEP PE R MOTOR CONTROL CIRCUIT
C
°
December 2001
1/11
L297
PIN CONNECTION
BLOCK DIA GRAM
(Top view)
L297/1
L297D
(L297/1 - L297D)
2/11
PIN FUNCTIONS - L297/1 - L297D
L297
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 V
s
13 SENS
2
5V supply input.
Input for load current sense voltage from power stages of phases
C and D.
14 SENS
1
Input for load current sense voltage from power stages of phases
A and B.
15 V
ref
Reference voltage for chopper circuit. A voltage applied to this pin
determines the peak load current.
16 OSC
An RC network (R to V
determines the chopper rate. This terminal is connected to ground
, C to ground) connected to this terminal
CC
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
N
°
19 HALF/
20
NAME FUNCTION
FULL Half/full step select input. When high selects half step operation,
RESET Reset input. An active low pulse on this input restores the
(continued)
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).
translator to the home position (state 1, ABCD = 0101).
THERMAL DATA
Symbol Parameter DIP20 SO20 Unit
R
th-j-amb
CIRCUIT OPERATION
The L297 is intended for use with a dual brid ge
driver, quad darlington array or discrete power
devices in step motor driving applications. It re-
Thermal resistance junction-ambient max 80 100
are chopped the non-active phase line of eac h 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.
ceives step cloc k , direction and m ode signals from
the systems controller (usually a microcomputer
chip) and generates control signals for the power
stage.
The principal functions are a translator, whic h generates the motor phase sequences, and a dual
PWM chopper circuit which regulates the current in
the motor windings. The t ranslator 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 energised). Two inhibit signals are also generated by
the L297 in half step and wa ve drive modes. These
signals, which connect directly to the L298’s enable
inputs, are intended to speed c ur rent dec ay 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 CONTR OL determines whether the
A common on-chip oscillator drives the dual chopper. It supplies pulses at the chopper rate which set
the two flip-flops FF1 and FF2. When the current in
a winding reaches the pr ogrammed peak v alue the
voltage across the sense resistor (connected to
one of the sense inputs SENS
and the corresponding comparator resets its
V
ref
or SENS2) equals
1
flip flop, interrupting the drive current until the next
oscillator pulse arrives. The peak current for both
windings is programmed by a v oltage divider on the
input.
V
ref
Ground noise problems in multiple configurations
can be avoided by synchronising the chopper oscillators. 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.
chopper will act on the phase lines ABCD or the
inhibit lines INH1 and INH2. When the phase lines
C/W
°
4/11
MOTOR DRIVING PHASE SEQUENCES
The L297’s translator generates phase sequences
for normal drive, wave drive and half step modes.
The state sequences and output waveforms for
these three modes are shown below. I n all cases
the translator advances on the low to high transis-
CLOCK.
tion of
HALF STEP MODE
Half step mode is selected by a high level on the HALF/
L297
Clockwise rotation is indicate; for anticlockwise rotation the sequences are simply rever sed
restores the translator to state 1, where ABCD =
0101.
FULL input.
RESET
NORMAL DRIVE MODE
Normal drive mode (also called "two-phase-on" drive) is selected by a low level on the HALF/
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.
FULL input
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/
when the translator is at an even numbered state (2, 4, 6 or 8).
FULL input
ELECTRICAL CHARACTERISTICS
(Refer to the block diagram T
= 25°C, Vs = 5V unless otherwise
amb
specified)
Symbol Parameter Test conditions Min. Typ Max. Unit
V
Supply voltage (pin 12) 4.75 7 V
s
Quiescent supply current (pin 12) Outputs floating 50 80 mA
I
s
Input voltage
V
i
(pin 11, 17, 18, 19, 20)
High 2 V
Input current
I
i
(pin 11, 17, 18, 19, 20)
V
V
Enable input voltage (pin 10) Low 1.3 V
en
High 2 V
Enable input current (pin 10)
I
en
V
Phase output voltage
V
o
(pins 4, 6, 7, 9)
I
V
Inhibit output voltage (pins 5, 8) Io = 10mA V
inh
Low 0.6 V
s
V
V
Io = 10mA V
= 5mA V
o
= L 100
i
= H 10
i
= L 100
en
= H 10
en
OL
OH
inh L
0.4 V
3.9 V
0.4 V
A
µ
s
V
A
µ
V
A
µ
A
µ
I
V
SYNC
Sync Output Voltage Io = 5mA V
I
= 5mA V
o
= 5mA V
o
6/11
inh H
SYNC H
SYNC V
3.9 V
3.3 V
0.8
L297
ELECTRICAL CHARACTERISTICS
(continued)
Symbol Parameter T est conditions Min. Typ Max. Unit
I
V
V
V
t
t
RCLK
leak
sat
off
I
o
ref
CLK
t
S
t
H
t
R
Leakage current (pin 3) VCE = 7 V 1
Saturation voltage (pin 3) I = 5 mA 0.4 V
Comparators offset voltage
(pins 13, 14, 15)
Comparator bias current
(pins 13, 14, 15)
V
= 1 V
ref
-100
5mV
10
Input reference voltage (pin 15) 0 3 V
Clock time 0.5
Set up time 1
Hold time 4
Reset time 1
Reset to clock delay 1
A
µ
A
µ
s
µ
s
µ
s
µ
s
µ
s
µ
Figure 1.
7/11
L297
APPLICATION INFORMATION
TWO PHASE BIPOLA R STE PP E R MO TOR CONTROL CIRCUIT
This circuit drives bipolar stepper motors with winding currents up to 2A. The diodes are fast 2A types.
Figure 2.
Figure 3 :
8/11
Synchronising L297s
L297
DIM.
MIN. TYP. MAX. MIN. TYP. MAX.
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
Z 1.34 0.053
mm inch
OUTLINE AND
MECHANICAL DATA
DIP20
9/11
L297
DIM.
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
K 0˚ (min.)8˚ (max.)
mm inch
OUTLINE AND
MECHANICAL DATA
SO20
B
e
D
1120
110
L
h x 45˚
A
K
A1
C
H
E
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 i ts us e. No license is granted
by implication or otherwise under any patent or patent rights of STMicroelectroni cs . Specification menti oned i n this publication are subject to
change without notic e. This publication supersedes and replaces all information previously suppl ied. 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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© 2001 STMicroelectronics – Printed in Italy – All Rights Reserved
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11/11
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