STMicroelectronics Fully integrated stepper motor driver mounting the L6472 in a high power PowerSO package EVAL6472PD EVAL6472PD データシート

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DocID022729 Rev 3

         

When the target current is decreased by a microstep change (falling step), the device 
performs a fast decay in order to reach the new value as fast as possible. Anyway, 
exceeding the fast duration may cause a strong ripple on the step change. The L6472 
device automatically adjusts these fast decays reducing the current ripple.

At reset, the fast decay value (t

FALL

) is set to FALL_STEP/4 (T_FAST register). The t

FALL

 

value is doubled every time, within the same falling step, an extra fast decay is necessary to 
obtain an ON time greater than TON_MIN. The maximum t

FALL

 value is equal to 

FALL_STEP.

At the next falling step, the system uses the last t

FALL

 value of the previous falling step. 

Stopping the motor or reaching the current sine wave zero crossing causes the current 
control system to return to the reset state.