STK672-640C-E View Datasheet(PDF) - ON Semiconductor

Part Name

Description

Manufacturer

STK672-640C-E

2-phase Stepping Motor Driver

ON Semiconductor 

STK672-640C-E

(5) When mounting multiple drivers on a single PC board

When mounting multiple drivers on a single PC board, the GND design should mount a VCC decoupling

capacitor, C1, for each driver to stabilize the GND potential of the other drivers. The key wiring points are as

follows.

24V

5V

Input

Signals

GND

9

Motor

1

IC1

2

6

19 18

Input

Signals

9

Motor

2

IC2

2

6

19 18

Input

Signals

Short

Thick and short

Thick

9

Motor

3

IC3

2

6

19 18

GND

(6) VCC operating limit

When the output (for example F1) of a 2-phase stepping motor driver is turned OFF, the AB phase back

electromotive force eab produced by current flowing to the paired F2 parasitic diode is induced in the F1 side,

causing the output voltage VFB to become twice or more the VCC voltage. This is expressed by the following

formula.

VFB = VCC + eab

= VCC + VCC + IOH × RM + Vdf (1.5 V)

VCC: Motor supply voltage, IOH: Motor current set by Vref

Vdf: Voltage drop due to F2 parasitic diode and current detection resistor R1, RM: Motor winding resistance

value

Using the above formula, make sure that VFB is always less than the MOSFET withstand voltage of 100V. This

is because there is a possibility that operating limit of VCC falls below the allowable operating range of 46V, due

to the RM and IOH specifications.

VCC

VCC

A phase

The pass of

drain current

F1

ON

AB phase

A phase

Eab is induced by

inducing M.

VFB

M

eab

F2

VCC

OFF F1

OFF

AB phase

eab

The pass of

negative current

M

F2

OFF

R1

GND

R1

GND

The oscillating voltage in excess of VFB is caused by LCRM (inductance, capacitor, resistor, mutual inductance)

oscillation that includes micro capacitors C, not present in the circuit. Since M is affected by the motor

characteristics, there is some difference in oscillating voltage according to the motor specifications. In addition,

constant voltage drive without constant current drive enables motor rotation at VCC ≥ 0V.

No. A2116-26/27

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