2-Phase Stepper Motor Unipolar Driver IC (2-Phase/1-2 Phase Excitation)
SLA7032M/SLA7033M
Application Notes
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).
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).
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
the chopping OFF time. (r
3
, r
4
, C
1
, and C
2
in the catalog)
(2) Remove the resistors and capacitors attached for preventing
noise in the detection voltage V
RS
from causing malfunction-
ing and short the sections from which the resistors were re-
moved using jumper wires. (r
5
, r
6
, C
3
, and C
4
in the catalog)
(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)
SYNC_A
TTL, etc.
SYNC_B
SLA7032M
SLA7033M
SYNC voltage : Low
Chopping asynchronous
SYNC voltage : High
Chopping 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
5V
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
∆V
REF
varies depending on the values of R1
and R2, determine these values for when the motor is not run-
ning within the range where the two phases are synchronized.
R1
V
REF
R2
3
14
REF_A
REF_B
40Ω
(typ.)
40Ω
(typ.)
V
REF
waveform
V
REF
0
To comparator
(high impedance)
SLA7032M
SLA7033M
Sync/async switching
signal
ONE SHOT
(tw=2
µ
S)
FET A/A
gate drive signal
ONE SHOT
(tw=2
µ
S)
FET B/B
gate drive signal
Synchronous circuit operating waveform
V
REF
Phase A
0
V
RS
V
REF
Phase B
0
V
RS
Synchronous circuit OFF
Synchronous circuit ON
SLA7032M/SLA7033M
31
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