STK672-210-E

No. 7464-5/10

Setting the Motor Current Peak Value (IOH)

IOH ≈ Vref ÷ Rs

Vref: STK672-210-E pin 12 input voltage

Rs: STK672-210-E internal current detection resistor (0.195

Ω ±2%)

Model of the Motor Current Flowing into the Driver IC (pins 2, 3, 4, and 5)

Vref = (Ro2

÷ (Ro1 + Ro2)) × VCC2

VCC2 = 5V

Current Switching Techniques

Due to the input bias current (IIB) specifications, Ro1 must be under 100kΩ.

The figures below present sample circuits that temporarily switch the motor current when, for example a held motor

stops.

We recommend using the circuit structure in the figure at the left to minimize as much as possible the effects of the

saturation voltage of the reference voltage switching transistor.

Switching Circuit 1

Switching Circuit 2

Input Pin Circuits

Input pin

Circuit type

Pin 6, 7, 8, and 9

Pin 12

0

5V

Ro1

Ro3

Ro2

Vref

Ro1

Ro3

Ro2

Vref

5V

Vref

To one of the comparator

CR input

GND

VCC2

The 5V/GND switch shows how toff

time setting operates in the internal

block diagram on page 3. When

switched to GND, pull-down with an

input resistance of 20k

Ω is formed.

MOSFET gate signal

10k

Ω

5 V

10k

Ω

5V

To XB phase

XB phase PWM signal

X phase

(XB phase)