Datasheet

Functional description L6480
22/75 DocID023278 Rev 4
Automatic Full-step and Boost modes
When motor speed is greater than a programmable full-step speed threshold, the L6480
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 /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 on page 47).
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 sine wave
multiplied by sine(/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 sine wave (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
Microstepping
V
peak
sin(π /4 )x V
peak
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