31

SLA7032M/SLA7033M

SLA7032M/SLA7033M

2-Phase Stepper Motor Unipolar Driver IC (2-Phase/1-2 Phase Excitation)

sOutline

SLA7032M (SLA7033M) is a stepper motor driver IC developed

to reduce the number of external parts required by the conven-

tional SLA7024M (SLA7026M). This IC successfully eliminates

the need for some external parts without sacrificing the features

of SLA7024M (SLA7026M). The basic function pins are com-

patible with those of SLA7024M (SLA7026M).

sNotes on Replacing SLA7024M (SLA7026M)

SLA7032M (SLA7033M) is pin-compatible with SLA7024M

(SLA7026M). When using the IC on an existing board, the fol-

lowing preparations are necessary:

(1) Remove the resistors and capacitors attached for setting

(2) Remove the resistors and capacitors attached for preventing

ing and short the sections from which the resistors were re-

(3) Normally, keep pins 2 and 13 grounded because their func-

tions have changed to synchronous and asynchronous

switching (SYNC terminals). For details, see "Circuit for Pre-

venting Abnormal Noise When the Motor Is Not Running (Syn-

chronous circuit)." (Low: asynchronous, High: synchronous)

sCircuit for Preventing Abnormal Noise When the

Motor Is Not Running (Synchronous Circuit)

A motor may generate abnormal noise when it is not running. This

phenomenon is attributable to asynchronous chopping between

phases A and B. To prevent the phenomenon, SLA7032M

(SLA7033M) contains a synchronous chopping circuit. Do not leave

Synchronous circuit operating waveform

SYNC_A

SYNC voltage : Low

SYNC voltage : High

→ Chopping asynchronous

→ Chopping synchronous

TTL, etc.

SYNC_B

SLA7032M

SLA7033M

Sync/async switching

signal

To comparator

(high impedance)

REF_A

R1

R2

3

5V

REF_B

0

14

SLA7032M

SLA7033M

FET A/A

gate drive signal

40

Ω

(typ.)

40

Ω

(typ.)

FET B/B

gate drive signal

ONE SHOT

(tw=2

S)

µ

ONE SHOT

(tw=2

S)

µ

Phase A

0

Synchronous circuit ON

Synchronous circuit OFF

Phase B

0

Application Notes

the SYNC terminals open because they are for CMOS input.

Connect TTL or similar to the SYNC terminals and switch the

SYNC terminal level high or low.

When the motor is not running, set the TTL signal high (SYNC

terminal voltage: 4 V or more) to make chopping synchronous.

When the motor is running, set the TTL signal low (SYNC terminal

voltage: 0.8 V or less) to make chopping asynchronous. If chop-

ping is set to synchronous at when the motor is running, the motor

torque deteriorates before the coil current reaches the set value.

If no abnormal noise occurs when the motor is not running,

ground the SYNC terminals (TTL not necessary).

The built-in synchronous chopping circuit superimposes a trigger

signal on the REF terminal for synchronization between the two

phases. The figure below shows the internal circuit of the REF

terminal. Since the

and R2, determine these values for when the motor is not run-

ning within the range where the two phases are synchronized.