SLA7033M Electronic IC Chips 2-Phase Stepper Motor Unipolar Driver ICs

SLA7032M/SLA7033M

2-Phase Stepper Motor Unipolar Driver ICs

Absolute Maximum Ratings

Application Notes

■ Outline

SLA7032M (SLA7033M) is a stepper motor driver IC developed to reduce the number of external parts required by the conventional SLA7024M (SLA7026M). This IC successfully eliminates the need for some external parts without sacrificing the features of SLA7024M (SLA7026M). The basic function pins are compatible with those of SLA7024M (SLA7026M).

■ Notes on Replacing SLA7024M (SLA7026M)

SLA7032M (SLA7033M) is pin-compatible with SLA7024M (SLA7026M). When using the IC on an existing board, the following preparations are necessary:

(1) Remove the resistors and capacitors attached for setting the chopping OFF time. (r₃, r₄, C₁, and C₂ in the catalog)

(2) Remove the resistors and capacitors attached for preventing noise in the detection voltage V_RS from causing malfunctioning and short the sections from which the resistors were removed using jumper wires. (r₅, r₆, C₃, and C₄ in the catalog)

(3) Normally, keep pins 2 and 13 grounded because their functions have changed to synchronous and asynchronous switching (SYNC terminals). For details, see "Circuit for Preventing Abnormal Noise When the Motor Is Not Running (Synchronous circuit)." (Low: asynchronous, High: synchronous)

■ Circuit 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 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 chopping 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 ∆V_REF varies depending on the values of R1 and R2, determine these values for when the motor is not running within the range where the two phases are synchronized.

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