L6482H datasheet(21/73 Pages) STMICROELECTRONICS

21 / 73 page

L6482

Functional description

Doc ID 023768 Rev 2

21/73

6.4.1

Automatic Full-step and Boost modes

When motor speed is greater than a programmable full-step speed threshold, the L6482

switches automatically to Full-step mode; the driving mode returns to microstepping when

motor speed decreases below the full-step speed threshold.

The switching between the microstepping and Full-step mode and vice versa is always

performed at an electrical position multiple of

π/4 (Figure 6 and Figure 7).

Full-step speed threshold is set through the related parameter in the FS_SPD register

(Section 9.1.9).

When the BOOST_MODE bit of the FS_SPD register is low (default), the amplitude of the

voltage squarewave in Full-step mode is equal to the peak of the voltage sinewave multiplied

by sine(

π/4) (Figure 6). This avoids the current drop between the two driving modes.

When the BOOST_MODE bit of the FS_SPD register is high, the amplitude of the voltage

squarewave in Full-step mode is equal to the peak of the voltage sinewave (Figure 7). That

improves the output current increasing the maximum motor torque.

Figure 6.

Automatic Full-step switching in Normal mode

Phase A

Phase B

(2N+1) x

π /4

(2N+1) x

π /4

Full-Step

Microstepping

peak

sin(

π /4)x V

peak

AM15036v1

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