STK672-523-E

No. A2110-6/22

• Motor current peak value IOH setting

• When RO2 is open

IOH= [Vref×1k/(1k+3.9k)] ÷Rs= (Vref÷4.9) ÷Rs

The values 1k and 3.9k represent internal driver resistance values, while Rs represents the internal driver current

detection resistance.

Vref= (4.9k

÷ (4.9k+RO1)) ×5V (or 3.3V) =IOH×4.9×Rs

The value 4.9k represents the series resistance value of the internal driver values of 1k and 3.9k.

• If RO2 is connected

IOH= [Vref×1k/ (1k+3.9k)] ÷Rs= (Vref÷4.9) ÷Rs

The values 1k and 3.9k represent the internal driver resistance values, while Rs represents the internal driver current

detection resistance.

Vref= (R0x

÷ (RO1+R0x)) ×5V (or 3.3V) =IOH×4.9×Rs

= [(4.9k

×RO2) ÷ ((4.9k×RO2) +RO1× (4.9k+RO2))] ×5V(or 3.3V)

R0x= (4.9k

×RO2) ÷ (4.9k+RO2)

Rs represents the current detection resistance inside the HIC, while the value 4.9k in the formula above represents the

internal resistance value of the Vref pin.

Rs=0.11

Ω when using the STK672-543-E

Rs=0.165

Ω when using the STK672-533-E

Rs=0.33

Ω when using the STK672-523-E

[Smoke Emission Precuations]

If any of the output pins 2, 3, 4, and 5 is held open, the electrical stress onto the driver due to the inductive energy

accumulated in the motor could cause short-circuit followed by permanent damage to the internal MOSFET. As a result,

the STK672-523-E may give rise to emit smoke.

Input Pin Functions

Pin Name

Pin No.

Function

Input Conditions When Operating

CLOCK

9

Reference clock for motor phase current switching

Operates on the rising edge of the signal

MODE

8

Excitation mode selection

Low: 2-phase excitation

High: 1-2 phase excitation

CWB

10

Motor direction switching

Low: CW (forward)

High: CCW (reverse)

RESETB

11

System reset and A, AB, B, and BB outputs cutoff.

Applications must apply a reset signal for at least 10

μs

when VDD is first applied.

A reset is applied by a low level

ENABLE

12

The A, AB, B, and BB outputs are turned off, and after

operation is restored by returning the ENABLE pin to the

high level, operation continues with the same excitation

timing as before the low-level input.

The A, AB, B, and BB outputs are turned off by a low-

level input.

(1) A simple reset function is formed from D1, CO2, RO3, and RO4 in this application circuit. With the CLOCK input

held low, when the 5V supply voltage is brought up a reset is applied if the motor output phases A and BB are

driven. If the 5V supply voltage rise time is slow (over 50ms), the motor output phases A and BB may not be driven.

Increase the value of the capacitor CO2 and check circuit operation again.

(2) See the timing chart for the concrete details on circuit operation.

IOH

0