DocID023635 Rev 2

7/34

AN4158

Stepper motor basics

34

1.1

Full step and half step

The driving sequence described in the previous section is called full step one phase on (or

wave driving) because the rotor is moved by one step at a time feeding only one of the two

phases of the motor at a time.

It is also possible to drive both the phases in order to generate a magnetic field positioned

halfway between the two phases (1a, 2a, 3a and 4a positions in Figure 3). This driving

mode is called full step two-phase on (or normal driving). In this case, at the same phase

current, the magnetic field is higher by a factor of

multiplied by the same factor.

Figure 2. Torque during a step change

θ

Stat

θ

HOLD

θ

HOLD

-

θ

Rotor

T

Mot

T

Load

T

MAX

At the step change the displacement

angle is about 90° and the maximum

torque is applied

The rotor approaches

the target step position

AM15104v1