L6228Q_10 Datasheet, PDF (18/32 Pages) STMicroelectronics – DMOS driver for bipolar stepper motor

Circuit description
L6228Q
4.7
Normal drive mode (full-step two-phase-on)
A LOW level on the HALF/FULL input selects the full step mode. When the low level is
applied when the state machine is at an ODD numbered state the normal drive mode is
selected. Figure 19 shows the motor current waveform state diagram for the state machine
of the phase sequencer generator. The normal drive mode can easily be selected by holding
the HALF/FULL input low and applying a RESET. At start -up or after a RESET the state
machine is in state 1. While the HALF/FULL input is kept low, state changes following the
sequence 1,3,5,7,… if CW/CCW is high (Clockwise movement) or 1,7,5,3,… if CW/CCW is
low (Counterclockwise movement).
4.8
Wave drive mode (full-step one-phase-on)
A LOW level on the pin HALF/FULL input selects the full step mode. When the low level is
applied when the state machine is at an EVEN numbered state the wave drive mode is
selected. Figure 20 shows the motor current waveform and the state diagram for the state
machine of the phase sequence generator. To enter the wave drive mode the state machine
must be in an EVEN numbered state. The most direct method to select the Wave Drive
Mode is to first apply a RESET, then while keeping the HALF/FULL input high apply one
pulse to the clock input then take the HALF/FULL input low. This sequence first forces the
state machine to state 1. The clock pulse, with the HALF/FULL input high advances the
state machine from state 1 to either state 2 or 8 depending on the CW/CCW input. Starting
from this point, after each clock pulse (rising edge) will advance the state machine following
the sequence 2,4,6,8,… if CW/CCW is high (clockwise movement) or 8,6,4,2,… if CW/CCW
is low (counterclockwise movement).
Figure 18. Half step mode
3
4
5
2
6
1
8
7
I_OUTA
I_OUTB
Start Up or Reset
CLOCK
12345678
D01IN1320
Figure 19. Normal drive mode
I_OUTA
3
4
5
2
6
I_OUTB
1
8
7
Start Up or Reset
CLOCK
13 5 7 1 3 5 7
D01IN1322
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Doc ID 14321 Rev 4