L6228Q

Circuit description

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Figure 16.

Fast decay mode output stage configurations

Figure 17.

Slow decay mode output stage configurations

4.5

Stepping sequence generation

The phase sequence generator is a state machine that provides the phase and enable

inputs for the two bridges to drive a stepper motor in either full step or half step. Two full step

modes are possible, the Normal Drive Mode where both phases are energized each step

and the Wave Drive Mode where only one phase is energized at a time. The drive mode is

selected by the HALF/FULL input and the current state of the sequence generator as

described below. A rising edge of the CLOCK input advances the state machine to the next

state. The direction of rotation is set by the CW/CCW input. The RESET input resets the

state machine to state 1.

4.6

Half step mode

A HIGH logic level on the HALF/FULL input selects Half Step Mode. Figure 18 shows the

motor current waveforms and the state diagram for the Phase Sequencer Generator. At

Start-Up or after a RESET the Phase Sequencer is at state 1. After each clock pulse the

state changes following the sequence 1,2,3,4,5,6,7,8,… if CW/CCW is high (Clockwise

movement) or 1,8,7,6,5,4,3,2,… if CW/CCW is low (Counterclockwise movement).

A) ON TIME

B) 1

µs DEAD TIME

C) QUASI-SYNCHRONOUS

RECTIFICATION

D) 1

µs SLOW DECAY

D01IN1335

A) ON TIME

B) 1

µs DEAD TIME

C) SYNCHRONOUS

RECTIFICATION

D) 1

µs DEAD TIME

D01IN1336