®
L297
STEPPER MO TOR CONTROLLERS
NORMAL/WAVE DRIVE
HALF/FULL STEP MODES
CLOCKWISE/ANTICLOCKWISE DIRECTION
SWITCHMODE LOAD CURRENT REGULA-
TION
PR OGR AM MABLE LOA D CURRE NT
FEW EXTERNAL COMPONENTS
RESET INPUT & HOME OUTPUT
EN AB L E IN PU T
DESCRIPTION
The L297 Stepper Motor Controller IC generates
four phase drive signals for two phase bipolar a nd
f our phase unipolar step motors in m icrocomputer-
controlled applications. The motor can be driv en in
half step, nor mal and wawe drive modes and on-
chip PWM chopper circuits permit switch-mode
control of the current in the windings. A feature of
December 2001
Symbol Parameter Value Unit
VsSupply voltage 10 V
ViInput signals 7V
P
tot Total power dissipation (Tamb = 70°C) 1W
T
stg, TjStorage and junction temperature -40 to + 150 °C
A BSO L U T E MA XI MUM RATIN G S
this device is that it requires only clock, direction
and mode input s ignals. S ince the phas e ar e gen-
erated internally the burden on the microprocessor,
and the programmer, is great ly 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.
TW O PHASE BIPOLAR S TEP PER MOT O R CONTR OL CIRCUIT
DIP20 SO20
ORDERING NUMBERS : L297/1 (DIP20)
L297D (SO20)
1/11
PIN CONNECT ION (Top view)
BLOCK DIAGRAM (L297/1 - L297D)
2/11
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.
5INH1 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.
8INH2 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 Vs5V supply input.
13 SENS2Input for load current sense voltage from power stages of phases
C and D.
14 SENS1Input 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.
16 OSC An RC network (R to VCC, C to ground) connected to this terminal
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.
PIN FUNCTION S - L297/1 - L297D
3/11
L297
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).
PIN FUNCTION S - L297/1 - L297D (continued)
CIRCUIT OPERATI ON
The L297 is intended for use with a dual bridge
driver, quad darlington array or discrete power
devices in step motor driving applications. It re-
ceiv es step c loc k , direction and m ode signals from
the systems controller (usually a microcomputer
chip) and generates c ontrol signals for the power
stage.
The principal functions are a translator , whic h 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 b y
the L297 in half step and wa ve drive modes. These
signals, which connect directly to the L298’s enable
inputs, are intended to s peed 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
chopper will act on the phase lines ABCD or the
inhibit lines INH1 and INH2. When the phase lines
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.
A common on-chip oscillator drives the dual chop-
per . It supplies pulses at the chopper rate which set
the two flip-flops FF 1 and FF2. When t he current in
a winding r eaches the pr ogrammed peak v alue the
voltage across the sense resistor (connected to
one of t he s ense inputs S ENS1 or SENS2) equals
Vref and the corresponding comparator resets its
flip flop, interrupting the drive current until the nex t
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.
Symbol Parameter DIP20 SO20 Unit
Rth-j-amb Thermal resistance junction-ambient max 80 100 °C/W
THERMAL D ATA
4/11
L297
MOT O R DRIVING PHASE SEQ U ENCE S
The L297’s translator generates phase sequences
for nor mal dr ive, wave drive and half step modes.
The state sequences and output waveforms for
these three modes are shown below. In all cases
the translator advances on the low to high transis-
tion of CLOCK.
Clockwise rotation is indicate; for anticlockwise ro-
tation the sequences are simply reversed RESET
restores the translator to state 1, where ABCD =
0101.
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 i nput
when the translator is at an odd numbered state (1, 3, 5 or 7). In this mode the INH1 and INH2 outputs
remain high through out.
5/11
L297
MOT O R DRIVING PHASE SEQ U ENCE S (cont inued)
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 num bered state (2, 4, 6 or 8).
Symbol Parameter Test conditions Min. Typ Max. Unit
VsSupply voltage (pin 12) 4.75 7 V
IsQuiescent supply current (pin 12) Outputs floating 50 80 mA
ViInput voltage
(pin 11, 17, 18, 19, 20) Low 0.6 V
High 2 VsV
IiInput current
(pin 11, 17, 18, 19, 20) V
i
= L 100 µA
V
i
= H 10 µA
Ven Enable input voltage (pin 10) Low 1.3 V
High 2 VsV
Ien Enable input current (pin 10) V
en = L 100 µA
V
en = H 10 µA
VoPhase output voltage
(pins 4, 6, 7, 9) Io = 10mA VOL 0.4 V
I
o
= 5mA VOH 3.9 V
Vinh Inhibit output voltage (pins 5, 8) Io = 10mA Vinh L 0.4 V
I
o
= 5mA Vinh H 3.9 V
VSYNC Sync Output Voltage Io = 5mA VSYNC H 3.3 V
I
o
= 5mA VSYNC V 0.8
ELECTRICAL CHARACTERISTICS (Refer to the block diagram Tamb = 25°C, Vs = 5V unless otherwise
specified)
6/11
L297
Symbol Pa ra meter T est 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
(pins 13, 14, 15) Vref = 1 V
5mV
I
oComparator bias current
(pins 13, 14, 15)
-100 10 µA
Vref Input reference voltage (pin 15) 0 3 V
tCLK Clock time 0.5 µs
tSSet up time 1 µs
tHHold time 4 µs
tRReset time 1 µs
tRCLK Reset to clock delay 1 µs
ELECTRICAL CHARACTERISTICS (continued)
Figure 1.
7/11
L297
APPLICATION INFOR MATION
TW O PHASE BIPOLA R STE PPE R MOT O R CONT R OL CIRCUIT
This circuit drives bipolar stepper motors with winding currents up to 2A. The diodes are fa s t 2A types .
Figure 2.
Figure 3 : Synchronising L297s
8/11
L297
DIP20
DIM. mm inch
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
OUTLINE AND
MECHANICAL DATA
9/11
L297
110
1120
A
e
B
D
E
L
KH
A1 C
SO20MEC
h x 45˚
SO20
DIM. mm inch
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.)
OUTLINE AND
MECHANICAL DATA
10/11
L297
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use of s uch information nor for any infringe me nt of patents or other r i ghts of third parties which may result from i ts us e. No license is granted
by impli cat i on or otherwis e under any patent or pat ent rights of STM i croelect roni cs . Specific ation m entioned i n t his publ ication 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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L297
