![](/html/94/94e7/94e782954c53167f4f7861b392f435e5305d29a045cbcf258f0183b615577ab3/bg1.png)
STEPPER MOTOR CONTROLLERS
NORMAL/WAWEDRIVE
HALF/FULLSTEP MODES
CLOCKWISE/ANTICLOCKWISEDIRECTION
SWITCHMODE LOAD CURRENT REGULA-
TION
PROGRAMMABLELOAD CURRENT
FEW EXTERNALCOMPONENTS
RESET INPUT & HOME OUTPUT
ENABLEINPUT
DIP20 SO20
ORDERING NUMBERS
:L297 (DIP20)
L297D (SO20)
L297
L297D
DESCRIPTION
The L297/A/D Stepper MotorController IC generates four phase drive signals fortwo phasebipolar
and four phase unipolar step motors in microcomputer-controlled applications. The motor can be
drivenin half step, normal and wawedrive modes
and on-chip PWM chopper circuits permit switchmode control of the current in the windings. A
featureof this device is that it requires only clock,
directionand modeinput signals.Since the phase
are generated internally the burden on the microprocessor,andtheprogrammer,is greatlyreduced.
Mounted in DIP20 and SO20 packages,the L297
can be used with monolithicbridge drives such as
the L298N or L293E, or with discrete transistors
and darlingtons.
ABSOLUTEMAXIMUMRATINGS
Symbol Parameter Value Unit
V
V
P
T
stg,Tj
Supply voltage 10 V
s
Input signals 7V
i
Totalpower dissipation (T
tot
Storage and junction temperature -40 to + 150 °
=70°C) 1 W
amb
TWOPHASE BIPOLARSTEPPER MOTORCONTROL CIRCUIT
C
August 1996
1/11
![](/html/94/94e7/94e782954c53167f4f7861b392f435e5305d29a045cbcf258f0183b615577ab3/bg3.png)
PIN FUNCTIONS- L297/L297D
N° NAME FUNCTION
L297-L297D
1 SYNC Output of the on-chip chopper oscillator.
The SYNC connections The SYNC connectionsof 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 powerstage.
5 INH1 Activelow inhibit control for driver stage of Aand B phases.
When a bipolar bridge is used this signal can be used to ensure
fastdecay of load current when a winding is de-energized.Also
used by chopper to regulate load current ifCONTROL input is low.
6 B Motor phase B drive signal for powerstage.
7 C Motor phase C drive signal forpower stage.
8 INH2 Activelow inhibit control for drive stages of C and D phases.
Same functions as INH1.
9 D Motor phase D drive signal forpower 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 onINH1 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
16 OSC
Reference voltage for chopper circuit. A voltage applied to this pin
determines the peak load current.
An RC network (R to V
determines the chopper rate.This terminalis connected to ground
, C to ground) connected to this terminal
CC
on all butone 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 dependson connection
of windings.
Synchronized internally thereforedirection can be changed at any
time.
18 CLOCK Stepclock. An activelow pulse on this input advances the motor
one increment. The step occurs on the rising edge of this signal.
3/11
![](/html/94/94e7/94e782954c53167f4f7861b392f435e5305d29a045cbcf258f0183b615577ab3/bg4.png)
L297-L297D
PIN FUNCTIONS- L297/L297D(continued)
N° NAME FUNCTION
19 HALF/FULL Half/full step selectinput. When high selects half step operation,
20 RESET Reset input. An active low pulse on this input restores the
when low selects full step operation. One-phase-on full step mode
is obtained by selecting FULL when the L297’stranslator 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 thehome position (state 1, ABCD= 0101).
THERMALDATA
Symbol Parameter DIP20 SO20 Unit
R
th-j-amb
CIRCUITOPERATION
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-
Thermal resistance junction-ambient max 80 100 °
arechoppedthe non-activephase line of eachpair
(ABor CD)is activated(ratherthan interruptingthe
linethen active).InL297 +L298 configurationsthis
technique reduces dissipation in the load current
senseresistors.
ceivesstep clock,directionand mode signals from
the systems controller (usually a microcomputer
chip) and generates control signals for the power
stage.
Theprincipalfunctionsare a translator,whichgenerates the motor phase sequences, and a dual
PWMchoppercircuit whichregulatesthecurrentin
themotorwindings.The translatorgeneratesthree
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).Twoinhibit signals are also generated by
theL297in half stepand wavedrivemodes.These
signals,whichconnectdirectlyto the L298’senable
inputs, are intended to speed current decay when
a winding is de-energised.When the L297 is used
todrivea unipolarmotorthe chopper actson these
lines.
Aninputcalled CONTROLdetermineswhetherthe
A common on-chip oscillator drivesthe dual chopper.It suppliespulsesat thechopperratewhichset
thetwoflip-flopsFF1 and FF2.Whenthe currentin
awindingreachesthe programmedpeakvaluethe
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 currentuntil the next
oscillator pulse arrives. The peak current for both
windingsis programmedbya voltagedivideron the
input.
V
ref
Ground noise problems in multiple configurations
can be avoidedby synchronisingthe chopper oscillators.This is done by connecting all the SYNC
pins together,mounting the oscillator RC network
on one device only andgrounding the OSC pin on
all other devices.
chopper will act on the phase lines ABCD or the
inhibitlines INH1 and INH2.When the phaselines
C/W
4/11