NJM3770A 데이터 시트보기 (PDF) - Japan Radio Corporation

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NJM3770A

STEPPER MOTOR DRIVER

Japan Radio Corporation  

NJM3770A

s FUNCTIONAL DESCRIPTION

The NJM3770A is intended to drive a bipolar constant current through one winding of a 2-phase stepper motor.

Current control is achieved through switched-mode regulation, see figure 3 and 4.

Three different current levels and zero current can be selected by the input logic.

The circuit contains the following functional blocks:

• Input logic

• Current sense

• Single-pulse generator

• Output stage

Input logic

Phase input

The phase input determines the direction of the current in the motor winding. High input forces the current from

terminal MA to MB and low input from terminal MB to MA. A Schmitt trigger provides noise immunity and a delay

circuit eliminates the risk of cross conduction in the output stage during a phase shift.

Half- and full-step operation is possible.

External recirculation

diodes

21

3

RS

Motor Current

1

2

3

Fast Current Decay

Slow Current Decay

Time

Figure 3. Output stage with current paths

for fast and slow current decay.

200 mA/div

1 ms/div

0

100µs/div

Figure 4. Motor current (I ),

M

Vertical : 200 mA/div,

Horizontal: 1 ms/div,

expanded part 100 µs/div.

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