SGS Thomson Microelectronics L297D Datasheet

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

stg,Tj

Supply voltage 10 V

Input signals 7V

Totalpower dissipation (T

tot

Storage and junction temperature -40 to + 150 °

=70°C) 1 W

amb

TWOPHASE BIPOLARSTEPPER MOTORCONTROL CIRCUIT

August 1996

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L297-L297D

PIN CONNECTION (Topview)

L297

L297D

BLOCKDIAGRAM(L297/L297D)

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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

13 SENS

5V supply input.

Input for load current sense voltage from power stages of phases

C and D.

14 SENS

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

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.

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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

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

ref

or SENS2) equals

flip flop,interrupting the drive currentuntil the next oscillator pulse arrives. The peak current for both windingsis programmedbya voltagedivideron the

input.

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

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