STK673-011-E

No.A1137-5/15

Set Equation of Output Current IO Peak Value

IO peak = Vref ÷ K K = 0.63 (V/A)

where

Vref

≤ 0.5 × VCC2

Vref = VCC2 × Rox ÷ (R01 + Rox)

Rox = (R02

× 4.0kΩ) ÷ (R02 + 4.0kΩ)

• R02 is preferably set to be 100Ω in order to minimize the effect of the internal impedance (4.0kΩ ±30%) of

STK673-011-E

• For noise reduction in 5V system, put the GND side of bypass capacitor (220μF) of VCC1 (shown in a thick line in

the above Sample Application Circuit) in the vicinity of pins 27 and 28 of the hybrid IC.

• Set the capacitance value of the bypass capacitor C1 such that a ripple current of a capacitance, which varies in

accordance with the increase of motor current, lies in an allowable range.

• K in the above-mentioned set equation varies within ±5 to ±10% depending on the inductance L and resistance value

R of the used motor. Check the peak value setting of IO upon actual setting.

Input/Output Terminals Functions of 5V System

Terminal name

No.

Function

Conditions upon Functioning

0 = Low, 1 = High

Clock

11

Basic clock for switching phase current of motor

Input frequency range: DC to 50kHz

Minimum pulse width: 10

μs

High level duty: 40 to 60%

Rising edge in Mode C = 1

Rising and falling edge in Mode C = 0

Mode A

12

Sets excitation mode

See table listed below

Mode B

13

Sets excitation mode

See table listed below

Mode C

18

Sets excitation mode

See table listed below

TU

22

Sets excitation mode

Switches 2-3 phase excitation of step current to rectangular current

More effective in increasing torque than in lowering vibration of motor

See table listed below

Hold

14

Temporarily holds the motor in a state

0

CW/CCW

15

Switches the rotational direction of the motor

1 = CW, 0 = CCW

Enable

16

Turns OFF all of the driving MOSFET

0

Reset

17

System reset Make sure to input a reset signal of 10

μs or more

0

MOI

20

Monitors the number of revolution of the motor

Outputs 1 pulse of a high level signal per

one cycle of phase current

Vref

10

Sets the peak value of the motor current set at 0.63V per 1A

Maximum value 0.5

× VCC2 (4A max)

Excitation Mode Table

Input condition

Mode A

Mode B

Mode C

TU

Excitation No.

Excitation Mode

Number of current

steps

Number of clock pulse

per one cycle of

phase current

0

0

1

1

(1)

2-phase

1

6

0

1

1

1

(2)

2-3-phase

3

12

0

1

1

0

(3)

2-3-phase TU

1

12

1

0

1

1

(4)

W2-3-phase

6

24

1

1

1

1

(5)

2W2-3-phase

12

48

0

0

0

1

(6)

2-3-phase

3

6

0

0

0

0

(7)

2-3-phase TU

1

6

0

1

0

1

(8)

W2-3-phase

6

12

1

0

0

1

(9)

2W2-3-phase

12

24

As shown in the table, TU terminal is only effective for Excitation Nos. (3) and (7).

Although the present hybrid IC is not damaged even when TU = 0 is mistakenly input in Excitation, other than

Excitation Nos. (3) and (7), motor vibration or motor current may increase.

* Timing charts for 3-phase stepping motor driver is illustrated on pages 9 to 13 for exemplary operations of Enable

Hold, CW/CCW for Excitation Nos. (1), (2), (3), (4), (5) and (9), and Excitation No. (4).