LV8740V

No.A1864-10/23

Input Pin Function

(1) Chip enable function

This IC is switched between standby and operating mode by setting the ST pin. In standby mode, the IC is set to

power-save mode and all logic is reset. In addition, the internal regulator circuit and charge pump circuit do not

operate in standby mode.

ST

Mode

Internal regulator

Charge pump

Low or Open

Standby mode

Standby

Standby

High

Operating mode

Operating

Operating

(2) Drive mode switching pin function

The IC drive mode is switched by setting the DM pin. In STM mode, stepping motor channel 1 can be controlled by

the CLK-IN input. In DCM mode, DC motor channel 2 or stepping motor channel 1 can be controlled by parallel

input. Stepping motor control using parallel input is 2-phase or 1-2 phase full torque.

DM

Drive mode

Application

Low or Open

STM mode

Stepping motor channel 1 (CLK-IN)

High

DCM mode

DC motor channel 2 or stepping motor channel 1 (parallel)

STM mode (DM = Low or Open)

(1) STEP pin function

The excitation step progresses by inputting the step signal to the STP pin.

Input

ST

STP

Operating mode

Low

*

Standby mode

High

Excitation step proceeds

High

Excitation step is kept

(2) Excitation mode setting function

The excitation mode of the stepping motor can be set as follows by setting the MD1 pin and the MD2 pin.

Initial position

MD1

MD2

Excitation mode

Channel 1

Channel 2

Low

Low

2 phase excitation

100%

-100%

High

Low

1-2 phase excitation (full torque)

100%

0%

Low

High

1-2 phase excitation

100%

0%

High

High

W1-2 phase excitation

100%

0%

This is the initial position of each excitation mode in the initial state after power-on and when the counter is reset.

(3) Positional detection monitor function

Positional detection monitor MONI pin is an open drain output. When the excitation position is an initial position, the

MONI output becomes ON.

Please refer to (example of current wave type in each excitation mode).

(4)Constant-current control reference voltage setting function

This IC does the PWM fixed current chopping control of the current of the motor by the automatic operation in setting

the output current. The output current in which a fixed current is controlled by the following calculation type is set by

the resistance connected between the voltage and RF-GND being input to the VREF pin.

IOUT=(VREF/5)/RF resistance

*The above-mentioned, set value is an output current of each excitation mode at 100% time.

VREF input voltage attenuation function

ATT1

ATT2

Current setting reference voltage attenuation ratio

Low

Low

100%

High

Low

66.7%

Low

High

50%

High

High

33.3%