DocID14109 Rev 3

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AN2650

Decay modes

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4

Decay modes

During the ON phase the current in the motor coil increases. After an ON phase, an OFF

phase follows that always starts with the cross current protection time (tcc).

The cross current protection time is automatically chosen with the slew rate and is typically

in the range from 0.5 to 4 µs.

After the cross current protection time, a programmed decay mode follows.

The basic decay modes of the stepper motor driver L9942 are:

•

Slow decay

•

Fast decay

•

Advanced decay modes, which are combinations of the slow and fast decay modes.

4.1

Slow decay

The slow decay mode realizes a minimum loss of energy in the motor coil. This means the

current decrease in the motor coil is “slow”.

Slow decay is illustrated in Figure 6.