STK672-060-E

No.7441-8/19

Functional Description

External Excitation Chopper Drive Block Description

Driver Block Basic Circuit Structure

Since this hybrid IC adopts an external excitation method, no external oscillator circuit is required.

When a high level is input to

φA in the basic driver block circuit shown in the figure and the MOSFET is turned on, the

comparator + input will go low and the comparator output will go low. Since a set signal with the PWM period will be

input, the Q output will go high, and the MOSFET will be turned on as its initial value.

The current ION flowing in the MOSFET passes through L1 and generates a potential difference in Rs. Then, when the

Rs potential and the Vref potential become the same, the comparator output will invert, and the reset signal Q output

will invert to the low level. Then, the MOSFET will be turned off and the energy stored in L1 will be induced in L2 and

the current IOFF will be regenerated to the power supply. This state will be maintained until the time when an input to

the latch circuit set pin occurs.

In this manner, the Q output is turned off and on repeatedly by the reset and set signals, thus implementing constant

current control. The resistor and capacitor on the comparator input are spike removal circuit elements and synchronize

with the PWM frequency. Since this hybrid IC uses a fixed frequency due to the external excitation method and at the

same time also adopts a synchronized PWM technique, it can suppress the noise associated with holding a position

when the motor is locked.

Input Pin Functions

Pin No.

Symbol

Function

Pin circuit type

14

CLK

Phase switching clock

Built-in pull-up resistor CMOS Schmitt trigger input

15

CWB

Rotation direction setting (CW/CCW)

Built-in pull-up resistor CMOS Schmitt trigger input

17

RETURN

Forced phase origin return

Built-in pull-up resistor CMOS Schmitt trigger input

18

ENABLE

Output cutoff

Built-in pull-up resistor CMOS Schmitt trigger input

9, 10, 11

M1, M2, M3

Excitation mode setting

Built-in pull-up resistor CMOS Schmitt trigger input

12, 13

M4, M5

Vector locus setting

Built-in pull-up resistor CMOS Schmitt trigger input

16

RESET

System reset

Built-in pull-up resistor CMOS Schmitt trigger input

8

Vref

Current setting

Operational amplifier input

ITF02272

D1

Rs

L2

VCC1

IOFF

L1

φA

φA

MOSFET

AND

Q

S

R

800kHz

45kHz

Latch circuit

Noise

filter

CR

oscillator

Divider

Current

divider

M4

M5

Vref

A=1

+

–

Enable

φA (control signal)

ION