L6472 STMICROELECTRONICS [STMicroelectronics], L6472 Datasheet - Page 35

• Manufacturer Part Number: L6472
• Description: dSPIN fully integrated microstepping motor driver
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L6472
7.2
Auto-adjusted decay mode
During the current control, the device automatically selects the better decay mode in order
to follow the current profile reducing the current ripple.
At reset, the OFF time is performed by turning on both the low-side MOSFETs of the power
stage and the current recirculates in the lower half of the bridge (slow decay).
If, during a PWM cycle, the target current threshold is reached in a time shorter than the
TON_MIN value, a fast decay of TOFF_FAST/8 (T_FAST register) is immediately performed
turning on the opposite MOS of both half bridges and the current recirculates back to the
supply bus.
After this time, the bridge returns to the ON state: if the time needed to reach the target
current value is still less than TON_MIN, a new fast decay is performed with a period twice
the previous one. Otherwise, the normal control sequence is followed as described in
Section
Figure 17. Adaptive decay - fast decay tuning
When two or more fast decays are performed with the present target current, the control
system adds a fast decay at the end of every OFF time, keeping the OFF state duration
constant (t
by a microstep change (rising step), the system returns to normal decay mode (slow decay
only) and the t
Stopping the motor or reaching the current sinewave zero crossing causes the current
control system to return to the reset state.
7.1. The maximum fast decay duration is set by the TOFF_FAST value.
OFF
FAST
is split into t
value is halved.
OFF,SLOW
Doc ID 022729 Rev 1
and t
OFF,FAST
). When the current threshold is increased
Phase current control
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