L6472 STMICROELECTRONICS [STMicroelectronics], L6472 Datasheet - Page 33

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

L6472
7
7.1
Phase current control
The L6472 performs a new current control technique, named predictive current control,
allowing the device to obtain the target average phase current. This method is described in
detail in
order to follow the current profile.
Current control algorithm parameters can be programmed by the T_FAST, TON_MIN,
TOFF_MIN and CONFIG registers (see
details).
Different current amplitude can be set for acceleration, deceleration and constant speed
phases and when the motor is stopped through the TVAL_ACC, TVAL_DEC, TVAL_RUN
and TVAL_HOLD registers (see
regulated by the ADCIN voltage value (see
Each bridge is driven by an independent control system that shares the control parameters
only with other bridges.
Predictive current control
Unlike a classical peak current control system, that causes the phase current decay when
the target value is reached, this new method keeps the power bridge on for an extra time
after reaching the current threshold.
At each cycle the system measures the time required to reach the target current (t
After that the power stage is kept in a “predictive” ON state (t
mean value of t
in
Figure 15. Predictive current control
At the end of the predictive ON state the power stage is set in the OFF state for a fixed time,
as in a constant t
performed; the better decay combination is automatically selected by the L6472, as
described in
Figure
Section
15.
Section
SENSE
7.1. Furthermore, the L6472 automatically selects the better decay mode in
OFF
7.2.
current control. During the OFF state both slow and fast decay can be
in the last two control cycles (actual one and previous one), as shown
Doc ID 022729 Rev 1
Section
Section
7.4). The output current amplitude can also be
Section
9.1.11, 9.1.12,
6.15).
PRED
9.1.13
) for a time equal to the
Phase current control
and
9.1.18
for
SENSE
33/69
).